Royal Society of Chemistry

Solid State Chemistry Group Christmas Meeting

Hosted by

School of Chemistry, University of Glasgow and

Department of Pure and Applied Chemistry, University of Strathclyde

18th

– 19th

December 2014

Dear delegates, We are delighted to welcome you to Glasgow and to the RSC Solid State Chemistry Group Christmas meeting 2014. We gratefully acknowledge the support of the following sponsors for this event: Gold sponsors:

Silver sponsors:

We hope you enjoy the meeting. Dr Serena Corr and Dr Eddie Cussen Conference organisers

http://sscg2014.wordpress.com/

Plenary speakers We are delighted to welcome our plenary speakers for this meeting:

Professor Martin Jansen, Max Planck Institute for Solid State Research

Dr Ivana Evans, University of Durham

Professor Nicola Spaldin, ETH Zürich

Dr Matt Tucker, ISIS Neutron and Muon source

General information All lectures will take place in the Large Lecture Theatre in the Joseph Black Building at the University of Glasgow. Coffee break on Thursday 18th December will take place in the Conference Room in the School of Chemistry. Coffee break on Friday 19th December will take place in the Atrium of the Woolfson Medical Building. Students will be on hand to direct you to these venues. The poster session and conference dinner will take place in the Hilton Grosvenor Hotel on Byres Road, a short 10 minute walk from the conference venue. The poster session will start at 6pm in the Hilton hotel on Thursday 18th December, with a Civic Reception to be provided by the Lord Provost and City of Glasgow. Please set up your poster between 5.40pm and 6pm. Other facilities If you are travelling from Central Station to the University, you can take the underground system from Buchanan Street to Hillhead Street. There are numerous taxi ranks nearby the train station and the University. Wifi details Wifi is available through Eduroam. The SSID for the wireless network is broadcast as eduroam. The network access method is IEEE 802.1x using your “home” institution username and password. Visitors will need to use their home institution instructions and user name/password. Please see the following website for further details: http://www.gla.ac.uk/services/it/eduroam/forvisitors/

5

Abstracts for Oral contributions

6

Materials discovery - from atomic energy landscapes to phase diagrams

Plenary speaker

Martin Jansen

Max-Planck-Institut für Festkörperforschung, Stuttgart, Germany

http://www.fkf.mpg.de/jansen

Synthesis of novel solids is the pivotal starting point in innovative materials research. However, such an undertaking is still substantially impaired by lack of control and predictability. We present a concept that points the way towards rational planning of syntheses in materials chemistry. The foundation of the approach is the representation of the whole materials world, the known and not-yet-known chemical compounds, on an energy landscape. From this conception it follows that all chemical compounds capable of existence (both thermodynamically stable and metastable ones) are already present in virtuo on this landscape and that the full sets of respective properties are pre-determined. For the first step of synthesis planning the respective potential energy landscapes are computationally searched for (meta)stable candidates. Subsequently, the informations gained are transferred to finite temperatures, which enables to calculate phase diagrams, including metastable manifestations of matter, from first principles. The conception developed is complete and physically consistent; its feasibility has been proven, as will be demonstrated by examples of predicted and a posteriori realized inorganic solids. M. Jansen, K. Doll, J. C. Schön: Addressing chemical diversity by employing the energy landscape concept, Acta Cryst. A66 (2010) 518 – 534

7

Neutron studies of the fast ionic and high temperature phase of LiBH4 stabilised by anion substitution

Oral contribution

Irene Cascallana1,2, Edmund J. Cussen1, Duncan H. Gregory2

1Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland 2School of Chemistry, University of Glasgow, Joseph Black Building, Glasgow, G12 8QQ, Scotland

Email:irenec@chem.gla.ac.uk, web site: http://www.chem.gla.ac.uk/staff/duncang/

LiBH 4 has been suggested as a candidate as an electrolyte for lithium ion batteries. The fast ionic and high temperature hexagonal (h) phase of LiBH4 can be stabilised by Br- substitution.1,2,3 In our work hexagonal Li(BH4)1-xBrx, (0.29 ≤ x ≤ 0.5) have been isolated at room temperature . Li ion conducitivty is found to be optimum for higher BH4

- content, reaching a maximum at ca. x = 0.29. Powder neutron

diffraction can be used in order to solve the challenging crystal structure of these phases. Herein we report neutron studies of 7Li 11BD4:LiBr mixture from room temperature to 300 °C. Rotations have been proposed to describe the (BH4)

- anion motion in different s-block tetraborohydrides. The experimental results confirm that (BH4)

- is disordered across the anion sites with Br_ and can be aligned either up or down, suggesting a rotation of the borohydride anion. The anion rotation is consistent with the Li+ conduction mechanism previously reported by First Principal molecular dynamic (FPMD) methods.4

Figure 1: Crystal structure of 7L11BD4:LiBr (2:1). It shows the Br- anions (transparent light blue spheres) are displaced from the position occupied by the BD4

- anions (black spheres). The two tetrahedrons facing up or down are shown in light red (40% and 20% of possibility respectively). Left side, lithium atoms refined with anisotropic thermal factor at room temperature.

1. M. Matsuo and S. Orimo. Adv. Energy Mater. 2011, 1, 161–172 2. Martelli P.; Remhof A.; Borgschulte A.; Ackermann R.; Strässle T.; Embs J. P.; Ersnt M.; Matsuo M.;

Orimo S. A. Züttel, et al. J. Phys. Chem. A. 2011, 115, 5329–5334 3. Rude L. H.; Groppo E.; Arnbjerg L. M.; Ravnsbæk D. B.; Malmkjær R. A.; Filinchuk Y.; Baricco M.;

Besenbacher F.; Jensen T.R. J. Alloys Comp. 2011. 509, 8299–8305 4. Ikeshoji T.; Tsuchida E.; Morishita T.; Ikeda K.; Matsuo M.; Kawasoe Y.; Orimo S. Appl. Phys. Lett.

2009, 95, 221901

8

Control of superconductivity in layered lithium iro n selenide hydroxides Li1–xFex(OH)Fe1–ySe

Oral contribution

Hualei Sun,a,b Daniel N. Woodruff,a Simon J. Cassidy,a,c Genevieve M. Allcroft,a Stefan J. Sedlmaier,a Amber L. Thompson,a Paul A. Bingham,d Susan D. Forderd Simon Cartenet,d Nicolas Mary,d Silvia Ramos,e

Francesca R. Foronda,f Benjamin H. Williams,f Xiaodong Li,b Stephen J. Blundellf and Simon J. Clarkea

a Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QR, UK.

b Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Science, Beijing

100049, China.

c Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.

d Materials and Engineering Research Institute, Sheffield Hallam University, Howard Street, Sheffield, S1 1WB,UK

e School of Physical Sciences, Ingram Building, University of Kent, Canterbury, Kent, CT2 7NH, UK.

f Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford, OX1 3PU, UK.

Email:daniel.woodruff@chem.ox.ac.uk

The almost-stoichiometric tetragonal polymorph of iron selenide, Fe1.01Se, is a superconductor with a Tc of 8.5 K.1 Relatives and derivatives of FeSe exhibit Tcs exceeding 30 K. These include high-temperature-synthesised (~900 °C) phases A1–xFe2–2ySe2 (x ~ y ~ 0.2; so-called 2-4-5 phases)2 with a highly defective ThCr2Si2-type structure. Here the bulk of the sample is a Mott-Hubbard insulator with a large local moment on Fe and an ordered array of iron site vacancies,3 but superconductivity with Tc of about 30 K is often found in minority regions of the sample with much less iron deficiency and less alkali metal.4 To minimise the concentration of iron site vacancies in the FeSe layers, superconducting Fe1.01Se itself has been used in the synthesis, at ambient temperatures and below, of alkali metal/ammonia intercalates, with Tcs as high as 45 K.5 Herein we reveal a wide compositional range in a series of layered lithium iron selenide hydroxides Li 1–xFex(OH)Fe1–ySe (x ~ 0.2; 0.03 < y < 0.15) prepared by modified hydrothermal reactions.6 Control of the reactions reveals a correlation of the occurrence of superconductivity and increasing Tc, up to 39 K, with the minimisation of y, the concentration of iron vacancies in the iron selenide layer. This correlation of composition, structure and properties is underlined by the demonstration that post-synthetic reductive lithiation turns on bulk superconductivity producing materials with Tc > 40 K.

Figure 1. (a) Structure of the lithium iron selenide hydroxides with refinement against neutron diffraction data (HRPD at ISIS). (b) Superconductivity

in hydrothermally synthesised samples showing the full range of behaviour spanned by these samples. (c) Plot of the 001 reflection measured for a range of samples on I11 showing the correlation between the c lattice parameter and whether the compounds are superconducting.

References: 1. F.-C. Hsu, J.-Y. Luo, K.-W. Yeh, T.-K. Chen, T.-W. Huang, P. M. Wu, Y.-C. Lee, Y.-L. Huang, Y.-Y. Chu, D.-C. Yan and M.-K. Wu, Proc. Natl.

Acad. Sci., 2008, 105, 14262. 2. J.-G. Guo, S.-F. Jin, G. Wang, S.-C. Wang, K.-X. Zhu, T.-T. Zhou, M. He and X.-L. Chen, Phys. Rev. B, 2010, 82, 180520. 3. J. Bacsa, A. Y. Ganin, Y. Takabayashi, K. E. Christensen, K. Prassides, M. J. Rosseinsky and J. B. Claridge, Chem. Sci. 2011, 2, 1054. 4. Y. Texier, J. Deisenhofer, V. Tsurkan, A. Loidl, D. S. Inosov, G. Friemel and J. Bobroff, Phys. Rev. Lett., 2012, 108, 237002. 5. M. Burrard-Lucas, D. G. Free, S. J. Sedlmaier, J. D. Wright, S. J. Cassidy, Y. Hara, A. J. Corkett, T. Lancaster, P. J. Baker, S. J. Blundell and S. J.

Clarke, Nat. Mater., 2013, 12, 15. 6. X. F. Lu, N. Z. Wang, G. H. Zhang, X. G. Luo, Z. M. Ma, B. Lei, F. Q. Huang, and X. H. Chen, Phys. Rev. B, 2013, 89, 020507(R)

9

Everything Changes: Probing MOF Formation in a Model System

Oral contribution

H. H.-M. Yeung,1 Y. Wu,2 S. Henke,3 A. K. Cheetham,4 D. O’Hare2 and R. I. Walton5 1ICYS-MANA, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan

2Department of Chemistry, University of Oxford, Oxford, OX1 3TA 3Chair of Inorganic Chemistry II, Ruhr-University Bochum, 44801 Bochum, Germany

4Department of Materials Science & Metallurgy, 27 Charles Babbage Road, Cambridge CB3 0FS 5Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL

Email:YEUNG.Hamishheiman@nims.go.jp, web site: hamishyeung.wordpress.com

From their humble beginnings in the 1990’s as Chemistry’s molecular equivalent of Tinkertoy®,

Metal-Organic Frameworks, MOFs, now find themselves investigated for several advanced applications. These include, in addition to conventional gas storage and separations, applications that exploit flexibility, tunability and synergy between “organic” and “inorganic” components in these unique materials.1 Yet, in order to make the difficult transition from interesting materials to functional materials, a deeper understanding of MOF formation is required, which will result in greater control over device fabrication and enable the targeted design of new MOFs for specific applications.2

The lithium tartrates – lightweight analogues of Rochelle Salt, the first ferroelectric – are a unique

model case for investigating structures, energetics and formation behaviour of MOFs. The crystal structures of eight anhydrous polymorphs are known, for which the relative formation energies have been calculated and related to various structural features.3,4 A systematic ex-situ study of various reaction conditions also attempted to relate synthesis and structure, gaining some insight into the process of MOF formation.5

Figure 1: Shedding light on the dark art of MOF phase behaviour using in-situ synchrotron X-ray diffraction.

By combining new in-situ synchrotron X-ray diffraction measurements6 with previous structural and thermodynamic information, we have now revealed more detailed insight than ever before into the formation of lithium tartrates as a function of reaction temperature, time and solvent. In monitoring the reaction evolution in real time, not only have we uncovered a wide range of kinetic and phase selection behaviours, but we have observed previously unknown crystalline reaction intermediates. This suggests a new formation mechanism for these intriguing new materials, which is expected to lead to advances in MOF device fabrication.

1. S. Horike, S. Shimomura, and S. Kitagawa, Nat. Chem., 2009, 1, 695–704. 2. M. D. Allendorf, A. Schwartzberg, V. Stavila, and A. A. Talin, Chem. - Eur. J., 2011, 17, 11372–88. 3. H. H.-M. Yeung, M. Kosa, M. Parrinello, P. M. Forster, and A. K. Cheetham, Cryst. Growth Des.,

2011, 11, 221–230. 4. H. H.-M. Yeung, M. Kosa, M. Parrinello, and A. K. Cheetham, Cryst. Growth Des., 2013, 13, 3705–

3715. 5. H. H.-M. Yeung and A. K. Cheetham, Dalton Trans., 2014, 43, 95–102. 6. S. J. Moorhouse, N. Vranješ, A. Jupe, M. Drakopoulos, and D. O’Hare, Rev. Sci. Instrum., 2012, 83,

084101.

10

The prediction and experimental observation of compositional order in binary platinum alloys

Oral contribution

Branton J. Campbell

Department of Physics & Astronomy, Brigham Young University, Provo Utah 84602, USA Department of Chemistry, Durham University, Durham, DH1 3LE, UK

branton_campbell@byu.edu, http://www.physics.byu.edu/faculty/campbell

Alloys of platinum whose functional properties are enhanced by ordering of the solute atoms have

potential applications as superior catalysts, cathode materials, temperature and corrosion-resistant components, and even jewelry products. By combining first principles calculations for structure prediction, innovative synthetic techniques for overcoming kinetic limitations, an innovative combination of TEM and synchrotron x-ray methods for treating highly-oriented polycrystals, and group-theoretical tools for diffraction analysis, we can now predict, identify and characterize subtle compositional orderings in Pt-rich binary alloys.1

Figure 1: Temperature-dependent kinematic superlattice intensities from Monte-Carlo simulations of compositional ordering in Pt3Cu.

1. C. Mshumi, L.R. Richey, KC Erb, C. W. Rosenbrock, L.J. Nelson, C.I. Lang, R.R. Vanfleet, H.T. Stokes, B.J. Campbell, and G.L.W. Hart, Acta Materialia 73, 326–336 (2014).

11

Oxide Ion Conductors for Energy Applications:

Twists and Hops in the Solid State

Plenary speaker

Ivana R. Evans

Department of Chemistry, Durham University, Durham DH1 3LE, U.K.

Email: ivana.radosavljevic@durham.ac.uk, web site: www.dur.ac.uk/chemistry/research/academic-groups/i.r.evans/

Meeting the future energy needs of the world’s growing population is one of today’s most significant scientific challenges. Different types of new, renewable and sustainable energy generation have been the subject of intense research, including solar, nuclear, wind and geothermal energy. Solid oxide fuel cell (SOFC) technology is a frontrunner in the short-to-medium term race to provide sustainable energy solutions, owing to the unique combination of high efficiency, fuel flexibility and environmental safety. Two factors have prevented the widespread commercialisation of SOFCs: system cost and reliability, and both stem from the high operating temperatures of the current technology (850–1000oC). Lowering the operating temperatures into the so-called intermediate temperature region (500–700oC) is therefore a major driver in SOFC research.

An in-depth understanding of the structural features associated with high ionic mobility is essential for the successful discovery and preparation of new oxide ion conductors capable of overcoming the limitations of the currently used materials. As materials structural complexity increases, crystallographic characterisation using a range of techniques (powder and single crystal, X-ray and neutron, in-situ studies) and state-of-the-art diffraction data analysis approaches, aided by DFT molecular dynamics simulations, is essential in providing this insight.

We have recently reported exceptional low- temperature oxide ion conductivity in Bi1-xVxO1.5+x (x = 0.095−0.087) phases, with σ = 3.5×10−2 S/cm at 450oC, the highest to-date in a stable 3D fluorite- type system. We have attributed this remarkable behaviour to the simultaneous presence of four key structural factors: a highly polarisable sublattice with vacancies, central atoms able to support variable coordination numbers and geometries, and the rotational flexibility of these coordination polyhedra, co-existing in a pseudo-cubic structure. 1 We have found similar structural features to lead to high oxide ion conductivity in a number of other materials with complex superstructures (vanadates, molybdates, tungstates, rhenates). 2-4

This presentation will focus on the new materials discovered and characterised and the crystallographic methods used to characterise them. In particular, it will emphasise how a combination of careful crystallographic work, computational methods and characterisation of physical properties is required to understand the complexity of next- generation functional materials. The methods adopted are relevant and widely applicable to energy-related and other functional materials.

(1) Kuang, X. J.; Payne, J. L.; Johnson, M. R.; Evans, I. R. Angew. Chem. Int. Ed. 2012, 51, 690. (2) Kuang, X. J.; Payne, J. L.; Farrell, J. D.; Johnson, M. R.; Evans, I. R. Chem. Mater. 2012, 24, 2162. (3) Ling, C. D.; Miiler, W.; Johnson, M. R.; Richard, D.; Rols, S.; Madge, J.; Evans, I. R. Chem. Mater. 2012, 24, 4607. (4) Payne, J. L.; Farrell, J. D.; Linsell, A. M.; Johnson, M. R.; Evans, I. R. Solid State Ionics 2013, 244, 35.

12

High-pressure High-Temperature phase diagram of the elpasolite La2NiMnO 6 - a neutron powder

diffraction study

Oral contribution

C.L. Bull, , W.G. Marshall, M.G.Tucker, K.S. Knight

ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxon, OX11 0QX, UK

Email:craig.bull@stfc.ac.uk, web site: http://www.isis.stfc.ac.uk/instruments/pearl/

Perovskites with the general formula ABO3 (where A is a lanthanide and B a transition

metal) are an important class of materials, characterized by subtle structural distortions from the cubic aristotype structure. Elpasolite (double) perovskites have the general formula ABB’X6, again with an idealised cubic structure (Fm-3m), in which BX6 and B’X6 octahedra alternate along the three four-fold cubic axes1. Many related materials crystallise at room temperature with a distorted variant of the regular elpasolite structure, with the distortions often disappearing upon heating. Distortions from the idealised cubic symmetry are caused by concerted rotations of the BO6 octahedra and displacements of the A & B cations within the cage and octahedron, respectively. These distortions are strongly temperature and pressure dependent, and can give rise to dramatic changes in dielectric properties, electrical resistivity and band gap2.

These double perovskite materials exhibit room-temperature semiconducting ferromagnetic and half-metallic magnetic properties which have attracted significant scientific attention due to their potential application in spintronic devices3. One such well-studied series of materials are the elpasoliteperovskites La2NiMnO6 and La2CoMnO6 which are of great technological interest as a result of their wide range of properties including magnetodielectric effects at room temperature4,5.

We have recently performed neutron diffraction studies on the La2NiMnO6 system looking at the effect of pressure and temperature on the crystal structure. The crystal structure of the room temperature monoclinic and high temperature rhombohedral phases have previously been determined using the HRPD high resolution neutron diffractometer at ISIS6. In this new combined pressure and temperature neutron diffraction study we have used the medium resolution PEARL instrument to investigate the p-T phase diagram using the Paris-Edinburgh press over the 0-10 GPa and 110-1200 K intervals. A high pressure study using HRPD has also been performed using a new clamp cell up to 8 kbar which made possible the collection of high-resolution neutron powder diffraction data using the HRPD back scattering detectors. In these studies we have mapped the phase diagram of La2NiMnO6 and revealed how the observed monoclinic to rhombohedral phase transition can be driven by both high temperature (at 290 K) and by pressure at lower temperatures.

We will present results from this interesting study and highlight the recent technical advances (available to all users at ISIS) which have made these detailed studies possible.

[1] I.N.Flerov et al., Mat Sci and Engineering 24, 81 (1998) [2] I.I.Mazin et al., Phys. Rev. Lett, 79, 733 (1997) [3] A.A. Wolf et al., Science, 294, 1488 (2001) [4] D.D. Awschalom et al., Sci. Am., 286, 66 (2002) [5] N.S. Rogado et al., Adv. Mater., 17, 2225 (2005) [6] C. L. Bull et al., J. Phys. Condens. Matter, 15, 4927 (2003)

13

The effects of codopants on the electronic structure of rhodium doped TiO2 and SrTiO3 single crystals

Oral contribution

E. Glover1, R. G. Palgrave1

1Department of Chemistry, 20 Gordon Street, University College London, London, WC1H 0AJ, United Kingdom

Email:e.glover@ucl.ac.uk

Titanium dioxide and strontium titanate are promising photocatalysts, particularly for water splitting as their band edges straddle the redox potentials for the reaction, a property essential for O2 and H2 evolution. However, their wide band gaps (>3.0 eV) mean that modifications must be made to allow them to be active under visible light. When investigating complex photocatalytic systems and their structure, it can be useful to do so using single crystals, which removes the influence of particle size, surface area, preferred orientation and other effects associated with nano- and micro-sized particles. Another benefit is that depth profiling can be used in conjunction with X-ray Photoelectron Spectroscopy to provide information about dopant diffusion.

It has been previously reported that TiO2 doped with Rh4+ possesses a Fermi level pinned at a lower

energy than that for undoped TiO2 due to the incomplete t2g acting as an acceptor level deep in the band gap1. The incorporation of a complete t2g energy level by doping with Rh3+ allows the Fermi level to remain close to the conduction band while also introducing visible light activity through introduction of Rh 4d states above the valence band maximum. However, since cation dopants in titanates will substitute Ti4+ sites Rh4+ is favoured. One way to mitigate this issue is to codope with a metal in the +5 oxidation state, to encourage incorporation of Rh3+ through charge compensation2.

The work to be presented investigates the above theory in TiO2 single crystals, doped with Rh and

Sb by solid state diffusion from doped TiO2 powder. The extent of dopant penetration into the crystal was determined by depth profiling. The same process was investigated in SrTiO3, which has a similar band gap to TiO2 (SrTiO3 indirect band gap = 3.25 eV3) and could be equally useful for photocatalytic purposes. Work in the literature shows that SrTiO3 doped with Rh and Sb, in contrast to TiO2, produces a p-type photocurrent4. We confirmed p-type character in doped SrTiO3 crystals and investigated the electronic reasons behind it, determining the optimum Sb/Rh dopant ratio.

(1) F. E. Oropeza; R. G.Egdell, Chemical Physics Letters 2011, 515, 249. (2) R. Niishiro.; R. Konta; H. Kato; W.-J. Chun; K. Asakura; A. Kudo, J. Phys. Chem. C 2007, 111, 17420. (3) K. van Benthem; C. Elsässer; R. H. French, Journal of Applied Physics 2001, 90, 6156. (4) S. Kawasaki; K. Akagi; K. Nakatsuji; S. Yamamoto; I. Matsuda; Y. Harada; J. Yoshinobu; F. Komori; R. Takahashi; M. Lippmaa; C. Sakai; H. Niwa; M. Oshima; K. Iwashina; A. Kudo, J. Phys. Chem. C 2012, 116, 24445.

14

Cubic [Cu(NH3)6-x]Cl 2 – Loss of Jahn-Teller distortion through NH3 deficiency. Oral contribution

Joachim Breternitz1, Agata Godula-Jopek2,3 Duncan H. Gregory1 1 School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, Scotland

2 Airbus Group Innovations, TX6, 81663 Munich,Germany 3 Institute of Chemical Engineering, Polish Academy of Sciences, 44100 Gliwice, Poland.

Email:Duncan.Gregory@glasgow.ac.uk, web site: http://www.gla.ac.uk/schools/chemistry/staff/duncangregory

The square bi-pyramidal distortion of octahedrally coordinated Cu2+ ions is probably one of the most prominent examples of Jahn-Teller distortion.[1] It is therefore not surprising, that the structure of [Cu(NH3)6-x]Cl2 at ambient conditions is distorted from the cubic K2PtCl6 structure type (Fm m) typical for hexammine metal halides into the translationengleiche sub-group I4/mmm.[2] Thermal analyses under flowing argon revealed that [Cu(NH3)6-x]Cl2 begins NH3 release just above room temperature with DTA and TGA profiles reflecting only the formation of the lower stoichiometric ammines CuCl2·nNH3 with n = 4, 2 as ammonia is lost in a stepwise process.

On heating [Cu(NH3)6-x]Cl2 under moderate ammonia pressure (~1.45 bar) however, a tetragonal-to-cubic phase transition is observed which corresponds to an apparent loss of the Jahn-Teller distortion in the complex cation (Figure 1). This phase transition is fully reversible and subsequent Rietveld refinements show that exceptionally, the structural change is not caused by a static or dynamic distortion in the crystal structure. Subsequent solid-state quantum chemical calculations allowed us to rationalise this apparent increase in symmetry as the consequence of the stabilisation of an intermediate non-stoichiometric complex (presumably in equilibrium with NH3 gas). We will demonstrate how these findings allow us a deeper insight into the decomposition mechanism of such ammines and might influence the functionality of the materials as ammonia stores.

Figure 1: Tetragonal-to cubic phase transition upon heating of [Cu(NH3)6-x]Cl2 followed by in-situ powder

XRD at beamline I11 at the Diamond Synchrotron Facility (right) together with the Cu coordination sphere in the tetragonal (bottom) and cubic (top) phase.

1. B. Murphy and B. Hathaway, Coord. Chem. Rev., 2003, 243, 237–262. 2. T. Distler and P. A. Vaughan, Inorg. Chem., 1967, 6, 126–129.

15

Tungsten-bronze-like tungstate double perovskites.

Oral contribution

O. J. Burrows1,A. Ahmad1, K. Knight2, A. Daoud-Aladine2, G.J. Nilsen3, M.A. de Vries1 1School of Chemistry and EaStChem, The Univeresity of Edinburgh, Edinburgh EH9 0JD, Scotland

2Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0QX, UK 3ILL, 71 Avenue des Martyrs, 38000 Grenoble, France

Email:m.a.devries@ed.ac.uk, web site: http://www.chem.ed.ac.uk/staff/academic-staff/dr-mark-de-vries/

Mott-insulating 5d transition metal compounds are currently of much interest because of the strong

couplings between the electronic structure and the magnetic degrees of freedom, which has been predicted to lead to novel electromagnetic phenomena.1 In this context we studied the previously reported double perovskite Ba2YWO6.

2 It was found that the Y site occupancy is variable between 2/3rd and up to at least 0.85, depending on the H2 partial pressure during sinter. The cubic Y-site deficient double perovskite Ba2Y2/3WO6 is a band insulating diamagnetic white powder with W6+. This is a metastable phase and further heating at 1200°C yields a material with a rhombohedral structure. As the Y occupancy (x) is increased a transition occurs from a band- to a Mott insulating electronic state with an increasing fraction of 5d1 W5+, and for x = 0.74 the compound is deep blue and paramagnetic. For x = 0.85 the sample exhibits Curie-Weiss paramagnetism above 50 K with a Weiss temperature of – 50 K, but without any obvious magnetic freezing transitions, reminiscent of the closely-related but stoichiometric Ba2YMoO6 double perovskite.3

Whereas the variable W oxidation enables variable A-site occupancy in the tungsten bronzes, these tungsten double perovskites support vacancies on the other B site. This is highly unusual and the metastability of Ba2Y2/3WO6 is unsurprising. The insulating nature of these compounds in the presence of a partially filled 5d1 valence band is likely to be due to the large distance between the W cations leading to a very narrow band, in combination with the very strong spin-orbit coupling of 5d transition metals. In summary, the W5+-containing double perovskites provide numerous exciting research opportunities because of their strongly spin-orbit coupled magnetism.

1. Chen, G., Pereira, R. & Balents, L. Exotic phases induced by strong spin-orbit coupling in ordered double

perovskites. Phys. Rev. B 2010, 82, 174440.

2. Kamata, K., Yoshimura, M., Nakamura, T. & Sata, T. Synthesis and properties of ordered perovskites A2(Ln3+M5+)O6. Chemistry Letters 1972, 8, 1201–1206.

3. de Vries, M. A., Mclaughlin, A. C. & Bos, J.-W. G. Valence Bond Glass on an fcc Lattice in the Double Perovskite Ba2YMoO6. Phys. Rev. Lett. 2010, 104, 177202.

16

From Solid State Chemistry to Cosmology: Studying the early universe under the microscope

Plenary speaker

Nicola Spaldin

Materials Theory, Department of Materials, ETH Zürich

Email: nicola.spaldin@mat.ethz.ch, web site: http://www.theory.mat.ethz.ch/people/head/nspaldin

What happened in the early universe just after the Big Bang? This is one of the most intriguing basic questions in all of science, but it is extraordinarily difficult to answer because of insurmountable issues associated with replaying the Big Bang in the laboratory. One route to the answer -- which lies at the intersection between cosmology and materials chemistry -- is to use laboratory materials to test the so-called "Kibble-Zurek" scaling laws proposed for the formation of defects such as cosmic strings in the early universe. Here I will show that a popular multiferroic transition metal oxide -- with its coexisting magnetic, ferroelectric and structural phase transitions -- generates the crystallographic equivalent of cosmic strings. I will describe how straightforward solution of the Schroedinger equation for the material allows the important features of its behavior to be identified and quantified, and present experimental results of the first unambiguous demonstration of Kibble-Zurek scaling in real materials.

17

Ion Conduction Mechanisms in Perovskite-based Solar Cell Materials

Oral contribution

Chris Eames, Jarvist Frost, Aron Walsh, M. Saiful Islam

Department of Chemistry, University of Bath, Bath BA2 7AY

Email: m.s.islam@bath.ac.uk, web site: http://people.bath.ac.uk/msi20/

Perovskite solar cells1,2 are attracting considerable interest since they recently exceeded 15% solar-to-electricity conversion efficiency for small-area devices. The active absorber layers are hybrid organic-inorganic perovskites formed from mixing metal and organic halides [e.g. (NH4)PbI3 and (CH3NH3)PbI3]. These materials exhibit efficiencies as high as purified silicon despite the simple and rapid synthesis method that might be expected to introduce chemical and structural defects. Knowledge of the fundamental defect chemistry and ion transport properties will therefore provide crucial information about the operation of these important new materials. In this presentation, we report on a computational investigation using DFT-based methods of the ion transport mechanisms and energy barriers in (CH3NH3)PbI3 including halide, protonic and full molecular defects. A series of movies are used to illustrate the novel mechanisms for ion transport found in this study. Energy barriers are determined for the various ion transport mechanisms and we provide estimates of the diffusion rate of each type of process.

Figure 1: Hybrid organic-inorganic CH3NH3-PbI3 perovskite structure showing corner-sharing PbI6 octahedra and CH3NH3 on the central ‘A’-site. Key: Iodine (purple), Lead (grey), hydrogen (white), nitrogen (blue), carbon (black).

1. Snaith et al., Science, (2012), 338, 643 2. J. M. Frost, K. T. Butler, F. Brivio, C. H. Hendon, M. van Schilfgaarde,

A. Walsh, Nano Lett., (2014), 14, 2584

18

(b)

(c)

Structural and Magnetic properties of Ca2Mn 3O8

Oral contribution

Laura. J. Vera Stimpson1* & Dr. Donna. C. Arnold1#

1Functional materials group, School of Physical Sciences, University of Kent, Canterbury, CT2 7NH

Email:* ljv6@kent.ac.uk and #d.c.arnold@kent.ac.uk

Porous manganese oxides are a versatile family of materials possessing a wide range of structures with diverse properties. These range from cation exchange and molecular absorptive properties to excellent electrochemical and magnetic characteristics, making them ideal candidates for a wide range of applications. Materials showing magneto-electric coupling have attracted considerable research interest due to their technological importance. Most compounds showing magneto-electric coupling belong to the perovskite family, although recently magnetoelectric-coupling has also been linked to magnetic frustration1-

2. This has given rise to research into a range of compounds showing complex triangular geometrically frustrated lattices, such as those belonging to the delafossite family1-3 (figure 1).

A material currently under investigation in this research project and which has attracted considerable research interest in the area of catalysis is Ca2Mn3O8

4. Ca2Mn3O8 exhibits a complex structure composed of infinite Mn3O8

4- sheets, with closely packed oxygen layers held together by Ca2+ ions (figure 2.a). This stacking arrangement provides octahedral sites for the manganese ions and trigonal prism sites for the calcium ions. Manganese ions occupy two distinct crystallographic sites within this structure, as seen in figure 2.a. Three-fourths of the available octahedral sites are occupied by Mn4+, with one-fourth of these sites being vacant. These ordered vacancies result in further tunnels running through the structure perpendicular to the layers. This structural arrangement allows for the manganese octahedral units to be arranged in a complex triangular arrangement (figure 2.b), similar to that seen in delafossites. Interestingly, Ca2Mn3O8 has received little research attention in the literature in terms of its magnetic

properties, despite the unarguably interesting structural characteristics, a factor which can be due in part to the difficulty in obtaining single phase Ca2Mn3O8. Our current research has shown that it is possible to synthesize phase pure Ca2Mn3O8 in bulk form. A series of low temperature Neutron Powder Diffraction (NPD) experiments have been carried out. These measurements have allowed, for the first time, to fully elucidate the magnetic structure of Ca2Mn3O8, as this material orders antiferromagnetically below 50K with both elastic and inelastic effects contributing to the overall magnetic moments. SQUID measurements also demonstrate the frustrated nature of this system, although strong antiferromagnetic (AFM) ordering within the layers causes the frustrated nature to become suppressed. In this paper we present our current findings in terms of structural and magnetic properties of Ca2Mn3O8

5. References: 1. M. Giot, L. C. Chapon, J. Androulakis, M. A. Green, P. G. Radaelli and A. Lappas, Phys. Rev. Lett., 2007, 99, 247211. 2. T. H. Arima, J. of the physical society of Japan, 2011, 80, 052001. 3. N. Terada, D. Khalyavin, P. Manuel, Y. Tsujimoto, K. Knight, P. Radaelli, H. Suzuki and H. Kitazawa, Phys. Rev. Lett., 2012, 109, 097203. 4. M. Najafpour, M. Kompany Zareh, A. Zahraei, D. Jafarian Sedigh, H. Jaccard, M. Khoshkam, R. Britt and W. Casey, Dalton Trans., 2013, 42, 14603. 5. L. J. Vera Stimpson, E. E. Rodriguez, C. Brown, G. Stenning, M. Jura and D. C. Arnold (2014) manuscript in preparation.

Figure 2: Schematic representation of Ca2Mn3O8 showing (a) the layers formed within the framework,

and (b) triangular arrangement of Mn atoms along the 'b' axis and (c) spin orientations within the manganese

octahedral sites.

(a)

Mn I Mn II Ca O

Figure 1: Schematic representation of the triangular arrangement of atoms in multiferroic delafossite

AgFeO23.

19

A-site cation size effect in unfilled ferroelectric tetragonal tungsten bronzes

Oral contribution

J. Gardner1, F. D. Morrison2

1School of Chemistry, University of St. Andrews, Fife KY16 9ST, Scotland Email: jg94@st-andrews.ac.uk, web site: http://chemistry.st-andrews.ac.uk/staff/fm/group/

The tetragonal tungsten bronze (TTB) structure, A12A24B12B28C4O30, consists of a corner-sharing

network of BO6 octahedra generating 3 types of ‘tunnel’ sites, Fig. 1(a). TTBs can be described as ‘stuffed’ when A and C sites are fully occupied, ‘filled’ with A-fully occupied but C empty, and ‘unfilled’ when vacancies are present within the A-sites. Distortion of the aristotype TTB structure is common due to octahedral tilting to relieve A-site-generated strain and results in superstructures and incommensurate modulations.1-3 These, often subtle, structural modifications have important ramifications for the dielectric properties and influence whether ferroelectric (FE), relaxor-ferroelectric (RFE) or dipole glass behavior is observed; commensurate superstructures tend to be ferroelectric whereas incommensurate structures result in relaxor-like properties.3 Recently we have studied a family of unfilled ferroelectric and relaxor-ferroelectric TTBs Ba4R0.67�1.33Nb10O30 (R = La, Nd, Sm, Gd, Dy and Y) using an array of (variable temperature) diffraction techniques (high resolution neutron, synchrotron x-ray and selected area electron). The structural modulations are controlled by varying the A1-(perovskite)site cation size with different R, and allows manipulation of the nature of the dipolar ordering. For example, Ba4La0.67�1.33Nb10O30 (R = La) exhibits a sequence of commensurate-RFE to disordered-paraelectric behaviour on heating, whereas the corresponding Nd-analogue undergoes an incommensurate ferroelectric-paraelectric transition, and for the remaining R all undergo simpler ferroelectric-paraelectric transitions. Additionally, the La-analogue displays electric field-driven ordering at intermediary temperatures between ferroelectric and paraelectric states. The crossover from relaxor to ferroelectric in this series has also been examined in more detail via Ba4La1-

xNdx�1.33Nb10O30. We also show a simplified approach where the degree of structural distortion of the aristotype cell (measured by tetragonality, c/a) can be used as a simple metric to predict the polar ordering temperature as TC increases with decreasing R and increasing c/a.4

Figure 1: (a) TTB structure showing unit cells of tetragonal aristotype (black solid line) and simple orthorhombic √2 × √2 × 2 superstructure (blue dashed line); and (b) ferroelectric polarisation-electric field loop and associated current switching.

3. P. J. Lin and L. A. Bursill, Acta Crystallogr. Sect. B-Struct. Sci., 1987, 43, 504 4. Ph. Labbe, H. Leligny, B. Raveau, J. Schneck, and J.C. Toledano, J. Phys. Condens. Matter., 1989, 2, 25 5. I. Levin, M. C. Stennett, G. C. Miles, D. I. Woodward, A. R. West and I. M. Reaney, App. Phys. Lett.,

2006, 89, 122908 6. J. Gardner and F.D. Morrison, Dalton Trans., 2014, 43, 11687

20

Colossal Magnetoresistance and Magnetic Ordering in Novel Mn2+ Pnictides

Oral contribution

Eve J. Wildman1, Janet M. S. Skakle1, Nicolas Emery2 and Abbie C. Mclaughlin*1

1University of Aberdeen, Meston Walk, AB24 3UE, Aberdeen, UK 2Universite Paris Est Creteil, 94320, Thiais, France

Email:e.wildman@abdn.ac.uk

We recently reported colossal magnetoresistance (CMR) in the electron doped oxypnictide series NdMnAsO1-xFx (x ≥ 0.05) 1. High resolution neutron diffraction results revealed antiferromagnetic ordering of Mn2+ arises below 356 K, with moments aligned parallel to the c axis. Below 23 K (TN (Nd)) the Nd3+ moments order antiferromagnetically along a, which induces a concurrent spin reorientation (TSR ~20 K) of the Mn moments which rotate from their previous alignment along c to aligning along a. The magnetic structure of these materials is the same as we reported for the parent compound, NdMnOAs 2, 3, however CMR is observed at temperatures below TSR (Figure 1). We propose a novel mechanism for CMR, as variable field neutron and resistivity measurements indicate a transition from an insulating antiferromagnetic state in zero field, to a semiconducting paramagnet in high fields. The MR is related to the magnitude of the antiferromagnetically ordered Mn2+ moment so that -

2/1

∆=C

MMR ; ∆M = M(0) – M(H), where M(H) is the Mn2+ moment in field, M(0) is the Mn2+ moment

when µ0H = 0 T and C is a constant (0.4 µB at 4 K). We also carried out substitutions on the rare earth site, fully replacing Nd with Pr. CMR is absent, but a sizeable negative magnetoresistance is observed below 35 K. Variable temperature synchrotron X-ray diffraction results revealed that this onset temperature corresponds with an orthorhombic structural transition. The structure and physical properties of both NdMnAsO0.95F0.05 and PrMnAsO0.95F0.05 will be presented in order to demonstrate that various MR mechanism exist for Mn based pnictides.

Figure 1: Magnetotransport data for NdMnAsO1-xFx - The variation of MR with temperature for x = 0.050, 0.065 and 0.080 evidencing CMR at low temperature in a 7T field.

1. E. J. Wildman, J. M. S. Skakle, N. Emery and A. C. Mclaughlin, J. Amer. Chem. Soc., 2012, 134, 8766. 2. N. Emery, E. J. Wildman, J. M. S. Skakle, G. Giriat, R. I. Smith and A. C. Mclaughlin, Chem. Comm., 2010, 46, 6777. 3. N. Emery, E. J. Wildman, J. M. S. Skakle, R. I. Smith, A. N. Fitch and A. C. Mclaughlin, Phys. Rev. B, 2011, 83, 14429.

21

Beyond Lithium-ion: Insights into Novel Phosphate Materials for Sodium-ion Batteries

Oral contribution

Stephen M. Wood1, Chris Eames1, Emma Kendrick2 and M. Saiful Islam1

1Department of Chemistry, University ofBath, Bath BA2 7AY, UK 2Sharp Laboratories Europe, Oxford, OX4 4GB, UK

Email:S.M.Wood2@bath.ac.uk, web site: http://people.bath.ac.uk/msi20/

Na-ion batteries have been touted as alternatives to Li-ion due to a higher natural abundance, more widespread distribution of sodium and the similar intercalation chemistry to lithium.1,2 Polyanionic phosphate materials have the potential to act as low cost cathodes, with stable framework structures, for Na-ion batteries.3 The mixed phosphate Na4Fe3(PO4)2P2O7 is an interesting new material reported as an attractive Na-ion cathode, displaying a low volume change upon cycling, indicative of long lifetime operation. Key issues surrounding intrinsic defects, Na-ion migration and voltage trends have been investigated through a combination of atomistic energy minimisation, molecular dynamics (MD) and density functional theory (DFT) simulations. These results suggest Na-ion diffusion extends across a 3D network of migration pathways with a low activation barrier, suggesting good rate capability. The voltage trends, explored with DFT, indicate that doping the Fe-based material with Mn has a relatively small effect on the cell voltage. However, doping with Ni can significantly increase the voltage of the cathode, providing a strategy for increasing the energy density.

1. M. S. Islam and C. A. J. Fisher, Chem. Soc. Rev.,2014, 43, 185 2. V. Palomeres, M. Casas-Cabanas, E. Castillo-Martinez, M. H. Han and T. Rojo, Energy Environ. Sci.

2013, 6, 2312 3. R. Tripathi, S. M. Wood, M. S. Islam and L. F. Nazar, Energy Environ. Sci. 2013,6, 2257

22

'RMCProfile: a step towards complex modelling’

Plenary Talk

Matt Tucker

ISIS Facility & Diamond Light Source, Harwell Oxford, Didcot, United Kingdom

Email: matt.tucker@stfc.ac.uk, web site: http://www.isis.stfc.ac.uk/People/matt_tucker5530.html

The importance of local structure and disorder in crystalline materials is being recognised more and more as a key property of many functional materials. From negative thermal expansion to improved fuel cell technology and solid state amorphisation to the ’nanoscale’ problem, a clear picture of the local atomic structure is essential to understanding these phenomena and solving the associated problems. Total scattering, an extension of the powder diffraction method, is increasingly being used to study crystalline materials. The unique combination of Bragg and diffuse scattering can be used to determine both the average structure and the short-range fluctuations from this average within a single experiment. To maximise the structural information from such data, three-dimensional atomic models consistent with all aspects of the data are required. RMCProfile[1] (see www.rmcprofile.org) expands the reverse Monte Carlo (RMC) modelling technique[2] to take explicit account of the Bragg intensity profile from crystalline materials. Analysis of the RMCProfile-generated atomic models gives more detailed information than is available directly from the data alone. I will give several examples where RMCProfile has been used to successfully study the structure and disorder of crystalline materials to illustrate its potential. As the systems being studied become more complex, the information from many experimental techniques and any prior chemical knowledge needs to be combined into one consistent atomic model. The continued development of RMCProfile and its new capabilities is moving us closer to the complex modelling paradigm[3] required to drive the discovery of new functional materials. References: [1] M. Tucker, D. Keen, M. Dove et al, J. Phys. Condens. Matter 2007, 19, 335218 [2] R. McGreevy, L. Pusztai, Mol. Simul., 1988, 1, 359 [3] S. Billinge, I. Levin, Science, 2007, 316, 561-565

23

Mesoporous silicon nitride and silicon–transition metal nitride composites for heterogeneous catalysis

Oral contribution

K. Sardar1, A.L. Hector1, W. Levason1, J.S.J Hargreaves2, J. Hriljac3 1Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UK

2School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, Scotland 3School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK

Email:K.Sardar@soton.ac.uk

Silicon nitride exhibits robust thermal and chemical stability and hence finds application in wide

range of processes. However, access to good quality materials has been challenging. Non-aqueous sol-gel synthesis produces silicon nitride with large surface area and mesoporosity1. Therefore, transition metal doping could provide heterogeneous catalysts for processes including ammonia synthesis.

Tetrakis(methylamino)silane (Si(NHMe)4) reacts with ammonia in presence of a catalytic amount of ammonium triflate to form monolithic gels and these have been pyrolysed between 200 and 1400 °C under ammonia. The pyrolysed materials have been characterised with nitrogen adsorption isotherms, 29Si MAS-NMR and synchrotron total scattering techniques. The materials exhibit meso-porosity with surface area within a range of 400-100 m2/g depending upon pyrolysis temperature. Both synchrotron pair distribution function analysis and solid state NMR studies have revealed that an amorphous phase starts crystallising into α-Si3N4 as the pyrolysis temperature is increased above 1200 °C. The process has been extended towards incorporation of transition metal centre within mesoporous silicon nitride for wider interest into heterogeneous catalysis. Thus, the use of V(NMe2)4 or Mo(NEt2)4 allows one to evenly distribute transition metals within gels which produce nanocrystallites of transition metal nitrides (VN and MoN) within the mesoporous silicon nitride matrix.

Figure 1: Experimental pair distribution function G(r) for silicon nitride samples prepared at temperatures shown.

1. A. L. Hector, Chemical Society Reviews 2007, 36 (11), 1745.

24

Total Scattering Studies of Disordered Bi-Fe-Mn Pyrochlore Oxides from Hydrothermal Synthesis

Oral contribution

L. M. Daniels1, R. I. Walton1, H. Y. Playford2, A. C. Hannon2 & J. -M. Grenèche3 1Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK

2ISIS, Rutherford Appleton Laboratory, Didcot, Oxford, OX11 0QX, UK 3Institut des Molécules et des Matériaux du Mans, UMR 6283 – CNRS LUNAM Université du Maine, 78085, Le Mans,

France

Email: l.m.daniels@warwick.ac.uk

Mixed-metal pyrochlore oxides receive increased amounts of attention for their diverse range of properties including: fast oxide-ion conductivity for solid oxide fuel cells, ferroelectricity, superconductivity, frustrated magnetism, and optics.1 The A2B2O6O′ pyrochlore structure is a system well known for its potential to accommodate various types of disorder that can lead to these interesting properties. These types of disorder often take the form of a deficient A site, or the mixing of metals across both the A and B sites, whilst there is flexibility in the O′ site through partial occupation, or various other species such as hydroxide, halides, or water that can occupy this site.2 Further disorder can be introduced by cations that carry stereochemically active electron lone pairs, such as Bi3+ and Pb2+, and this can induce static displacements into the A site cation sub lattice, which results in further disorder of the coordinated oxide ions.3 Such forms of disorder on a local scale can be often overlooked when studied using traditional diffraction techniques.

We report two new metastable pyrochlore oxides of compositions (Na0.6Bi1.4)(Fe1.06Mn0.17Bi0.77)O6.87 and (K0.24Bi1.51)(Fe1.07Mn0.15Bi0.78)O6.86 from low-temperature hydrothermal synthesis.4 The refinement of the structure against both X-ray and neutron Bragg data shows that the bismuth is mixed across both the A and B sites, and the compositions are also confirmed by inductively coupled plasma (ICP) analysis. It is shown through X-ray absorption near edge spectroscopy (XANES) that Bi5+ resides on the B site, whilst the larger, lone-pair Bi3+ ion is on the A site. XANES is also used to show that it is Mn4+ on the B site, and alongside Mössbauer spectroscopy, Fe3+ also.

Total neutron scattering data were collected on the GEM diffractometer at ISIS, the UK spallation neutron source. Pair distribution function (PDF) analysis has proved an ideal technique for the study of disordered materials, as it provides extra information about local and medium-range order not shown in the Bragg scattering.5 It has proved possible to fully model the disorder present on a local scale within these pyrochlores by using the Reverse Monte Carlo (RMC) technique with a box of atoms containing [6x6x6] unit cells. Magnetic measurements show a lack of long-range magnetic ordering which is typical of geometrically frustrated pyrochlores. The observed spin-glass like interactions occur at low temperatures, with the onset temperature depending upon the magnitude of the applied magnetic field.

Figure: Rietveld refinement (left) of Bragg data from GEM, and fit to the short-range PDF using RMC (right).

1. M. T. Weller, R. W. Hughes, J. Rooke, C. S. Knee and J. Reading, Dalton Trans., 2004, 19, 3032. 2. M. A. Subramanian, G. Aravamudan and G. V. Subba Rao, Prog. Solid State Chem., 1983, 15, 55. 3. Q. Zhou, P. E. R. Blanchard, B. J. Kennedy, C. D. Ling, S. Liu, M. Avdeev, J. B. Aitken, A. Tadich and

H. E. A. Brand, J. Alloy Compd., 2014, 589, 425. 4. L. Daniels, H. Y. Playford, J. -M. Grenèche, A. C. Hannon and R. I. Walton, Inorg. Chem., in press. 5. S. J. L. Billinge, Z. Kristallogr., 2004, 219, 117.

0 2 4 6 8 10

0

1

2

3

4

T(r

)/ b

arn

s Å–2

r / Å

Observed RMC fit

1.0 1.5 2.0 2.5 3.00

1

2

32e

96h

0.5 1.0 1.5 2.0 2.5

Observed Calculated Difference Peak position

Diff

ract

ed

Inte

sity

d-spacing/ Å

25

Local structure investigations of nanomaterials for Li-ion battery applications

Oral contribution

T. E. Ashton1, S. A. Corr1

1School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, Scotland

Email: t.ashton.1@research.gla.ac.uk, web site: http://corrgroupglasgow.com/

As global energy demands increase due to a rising population and growing industrial and

technological market, much focus has been afforded to the development of efficient energy storage materials. Li+ ion batteries present one of the most exciting avenues for such research and, most prominently, the synthesis of higher capacity electrode materials. Vanadate materials (VxOy) are an interesting family of compounds with highly tunable oxidation state chemistry which exhibit high theoretical capacities. VO2(B) exhibits a theoretical capacity of 323 mAh g-1, but realizing this maximum is a great challenge due to dynamic changes. We have successfully prepared phase-pure VO2(B) by two routes: solvothermal [VO2(B)_ST] and rapid microwave-assisted [VO2(B)_µλ]. It has been observed that the morphologies of VO2(B)_µλ can be tailored by irradiation time and exhibit a consistently higher capacity and capacity retention than VO2(B)_ST. Similar studies suggest this is due to a nano-sizing effect.1 We have also studied both VO2(B)_µλ and VO2(B)_ST by in-situ XAS studies (Figure 1) to elucidate the nature of local-structure changes within these materials upon electrochemical cycling.

Figure 1: In-situ XAS of VO2(B)_ µλ. XANES (left) shows a shift in photon energy due to the evolution of V4+ to V3+ with increasing lithiation. EXAFS (right) shows changes in the inter-atomic distances in real space.

1. G. Armstrong, J. Canales, A. R. Armstrong and P. G. Bruce, J. Power Sources, 2008, 178, 723-728 2. T. E. Ashton, J. Vidal Laveda, P. J. Baker, D. Maclaren, A. Porch, M. O. Jones and S. A. Corr, J. Mater.

Chem, A, 2014, 2, 6238-6245. 3. P. J. Baker, I. Franke, F. L. Pratt, T. Lancaster, D. Prabhakaran, W. Hayes and S. J. Blundell, Phys. Rev.

B, 2011, 84, 174403

26

Using µSR to investigate solid state materials

Oral contribution

F. C. Coomer1

1ISIS Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX, UK

Email: fiona.coomer@stfc.ac.uk, web site: http://www.isis.stfc.ac.uk/groups/muons/muons3385.html

Muon spectroscopy, using spin polarised muons, has many applications in the field of solid state

chemistry. The magnetic moment of the muon means that implanted muons can act as a local magnetometer, probing the behaviour of magnetic systems, as well as that of superconductors and of charge transport in materials. Positively charged muons can also act as a light analogue of the proton, giving rise to applications such as investigating hydrogen behaviour in materials and light particle diffusion.

An overview of the µSR technique and the capabilities of the ISIS pulsed muon source will be

presented, focusing in particular on areas that will be of interest to the solid state chemistry community. Examples will be given of cases where µSR has been used to elucidate unusual behaviour in some geometrically frustrated magnetic systems including the valence bond glass Ba2LuMoO6,

1 and unusual ordering in Ba2MnMoO6.

2

1. F. C. Coomer and E. J. Cussen, J. Physics: Condens. Matter 2013, 25, 082202. 2. F. C. Coomer, E. J. Cussen, A. D. Hillier and S. Ramos. In preparation.

27

In the Right Place at the Right Time: In-Situ Observation of Materials Formation

Oral contribution

Y. Wu,1 H.H.-M. Yeung,2 R.I. Walton,3 D. O’Hare1

1Department of Chemistry, University of Oxford, Oxford, OX1 3TA 2ICYS-MANA, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan

3Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL

Email: yue.wu@chem.ox.ac.uk, web site: http://users.ox.ac.uk/~dohgroup/

In chemical research, materials are generally first synthesised and prepared, and only then undergo characterisation. However, this approach allows the investigation of only one point in synthetic parameter space at a time. By using techniques that can take measurements within a reaction (i.e. in-situ) as it progresses, we can access a much larger section of parameter space resolved by an additional parameter such as time, temperature or reagent ratio. We present work on our development and usage of an IR furnace cell (‘ODISC’, the Oxford-Diamond In-Situ Cell – fig. 1)1 to perform in-situ characterisation of the formation of materials under a wide range of conditions. We have been able to obtain good quality in-situ data that is temperature and time resolved, using angular-dispersive and energy dispersive diffraction, and small angle scattering. This enables us to obtain structural data on intermediates and products, as well as information on kinetics and particle sizes.

Figure 1: ODISC furnace (left); example ODISC data from an in-situ PXRD experiment, showing the interconversion of phases during the formation of a metal-organic framework (right).

Some results obtained using the ODISC cell are presented. We show for the first time that the well-known pillared-paddlewheel family of metal-organic frameworks (‘MOFs’) form through metastable intermediate phases, which we have been able to characterise structurally and kinetically from in-situ data. We have also tested the cell for small-angle X-ray scattering experiments, which has allowed us to observe the formation and aggregation of nanoparticles under supercritical conditions. We welcome expressions of interest for collaborative experiments using this system. We are currently developing ODISC so that it can be used as a user facility on beamline I12 at the Diamond Light Source. The heating capability is both precise and rapid, reaching 1200-1300 °C in less than ten seconds. The wide-bore design and interchangeable reaction vessels allow a wide range of different reactions to be studied from moderate to extremely high temperatures. Examples of possible experiments include solvothermal synthesis using a full autoclave with stirring, high-temperature molten salt reactions, and synthesis in a sealed supercritical water reactor. 1. S. J. Moorhouse, N. Vranješ, A. Jupe, M. Drakopoulos, D. O’Hare (2012) Rev. Sci. Instrum. 83, 084101

28

Abstracts for poster contributions Poster Presenting author Poster title P1 Yashodhan Gokhale Green Manufacturing of Functional Nanomaterials: case study of silica P2 Chris Ainsworth Origins of Transition Metal Ordering in Ln2O2MSe2-type Layered Oxychalcogenides P3 Angel Arevalo-Lopez “Hard-Soft” synthesis of perovskite superstructures. P4 Oliver Burrows Short-ranged static magnetic order in Sr2CuWO6 with frustrated Cu(II) 2D square lattice P5 Mauro Davide Cappelluti Microwave-assisted hydrothermal synthesis of TiO2 particles for environmental processes P6 Simon Fellows Alkyl Chain Order/Disorder Transition in Copper Carboxylate Complexes P7 Heather F. Greer Early Stage Crystal Growth of ZnO Spherical Particles Constructed from Radially Aligned Nanocones P8 Harriet Hopper Discovery and Development of Novel Photocatalytic Perovskites P9 Jack Blandy Oxidative Deintercalation of Copper from Sr2MnO2Cu2-δS2 P10 James Cumby Structural and Magnetic Properties of MnxCo1-xSb2O4

P11 M. Grazia Francesconi Pd2.8Sn Nanoalloy on ZnO support – a Lead-Free Alternative to the Lindlar Catalyst

P12 Josefa Vidal Laveda Microwave synthesis of LiFe1-xMnxPO4 nanostructures as positive electrodes in Li-ion batteries P13 Kirsty McRoberts Non-Classical Crystal Growth of MIL-68(In) P14 Katherine Self Reversed Crystal Growth of Rhombohedral Calcite P15 John Lampkin Solvothermal Synthesis of a Novel 3-D Indium-Sulfide framework [(H2tren)2

2+]2[In4S8]4-

P16 Michael Pitcher Tilt Engineering of Spontaneous Polarisation and Magnetisation Above Room Temperature in a Bulk Oxide Material

P17 Adam McSloy Computational Investigation of Barium Orthotitanate for Application in SOFCs P18 Geoffrey Nelson Formation of AlSbO4 Islands via Sb-doped SnO2 thin films on R-plane Alumina substrates doped by thermal diffusion

P19 Panagiotis Mangelis Synthesis, Structure and Physical Properties of Co3-xNixSn2S2 (0 ≤ x ≤ 3) P20 Paul Brack Hydrogen generation from ferrosilicon P21 Prangya Sahoo Synthesis, Structure and Conductivity studies of co-doped ceria: CeO2−Sm2O3−Ta2O5 (Nb2O5) solid solution

P22 Jesús Prado-Gonjal Thermoelectric properties of Co1-2xFexNixSb3 (0 ≤ x ≤ 0.5) P23 Caroline Riedel Tin-based ternary photocatalysts P24 Simon Cassidy Metal-Ammonia Intercalated Iron Selenide Superconductors Studied In-Situ by Powder X-Ray Diffraction

P25 Irene Munaò Solvothermal synthesis of some sodium transition metal framework compounds for solid-state batteries P26 Sonia A. Barczak Thermoelectric Properties of the Fe and Al Substituted Chimney Ladder MnSi1.75 P27 Cameron Black Polymorphism in Vanadium OxuFluoride AVOF3 ladder systems, A = K, Rb, Cs P28 Daniel Cook Solvothermal Synthesis of Doped γ-Gallium Oxide P29 Parthiban Ramasamy Phase controlled synthesis of SnSe & SnSe2 hierarchical nanostructures made of single crystalline ultrathin nanosheets P30 Kayleigh Marshall Hydrofluorothermal synthesis of titanium fluorophosphates and fluorosulphates P31 Maryana Asaad Synthesis, Structure and Thermoelectric Properties of the of the Ti1-xVxCoSb1-xSnx Half-Heusler Alloys

P32 Giordano da Cunha Bispo Luminescence in undoped CaYAl 3O7 nanopowders produced via the Pechini Method P33 Chun-Hai Wang Incommensurate layered oxychalcogenide Ce2O2MnSe2 and a simple commensurate case (Ce0.78La0.22)2O2MnSe2

P34 Dominic Chaopradith Steam Reforming of Methane on Yttria-stabilsed Zirconia – a DFT Study

P35 Helen Playford How long is long enough? P36 Iona Ross Copper Chromium Oxide Delafossites For Cathode Side Applications in SOFCs

P37 Jakub Baran Misfit-Layered Cobaltites: a viable route to efficient thermoelectric materials P38 Elise Pachoud Crystal growth and physical properties of polar LiMP2O7, M=Fe, Cr

P39 Srinivasa Popuri Glass-like Thermal Conductivity in SrTiO3 Thermoelectrics Induced by A-site Vacancies P40 Sacha Fop Structure and Electrical Properties of Ba3MoNbO8.5

P41 Andrew Hector Oriented mesoporous templates for supercritical fluid electrodeposition P42 Charlotte Dixon Structure-Property Relationships in Ferroelectric LaFeO3 and Multiferroic Bi0.5La0.5FeO3 P43 Mako Ng Solid state synthesis of Cu2ZnSnS4 for photovoltaic application P44 Robert Walker Bismuth-Based Group IV Ternary Oxide Photocatalysts P45 Freddy Oropeza A Solution Chemistry Approach to Epitaxial Growth and Stabilisation of Bi2Ti2O7 Films P46 Christophe Didier A hexagonal perovskite polymorph Ba2InAlO5: structure solution woes. P47 Hugh Glass High voltage cathodes for Mg-ion batteries P48 Colin McKinstry Continuous Synthesis of Metal Organic Framework (MOF-5) P49 Craig McAnally Evaluation of MOF textural parameters - lessons for materials screening P50 Jennifer Heath NaFePO4 Cathodes for Sodium Batteries: Why is Olivine More Promising Than Maricite?

29

P1: Green Manufacturing of Functional Nanomaterials: case study of silica

Poster contribution

Joseph Manning, Yashodhan Gokhale, Craig Drummond and Siddharth V. Patwardhan*

Department of Chemical and Process Engineering, University of Strathclyde, Glasgow G1 1XJ

Email: Siddharth.Patwardhan@strath.ac.uk Web: www.svplab.com

The invention of mesoporous silicas, whichoffer well-defined and tunable pores with applications in medicine, separations and catalysis, has led to 20,000+ citations. However, because their synthesis is complex, multistep and energy intensive, they have been difficult to scale-up. We have invented an alternate green chemistry for silica synthesis1 and this presentation will demonstrate scaling-up bioinspired synthesis from mg to g-kg as a first step towards the manufacturing of functional nanomaterials.2 We will also demonstrate their applications in a wide ranging sectors such as drug delivery, biocatalysis and environmental decontamination. We will present results from our efforts towards scale-up manufacturing of bioinspired silica. A new, more industrially relevant method of mixing was investigated, and its effect on the extent of reaction was demonstrated. While using the larger vessel was found to decrease the precursor conversion and reproducibility over the smaller-scale method, carefully designed mixing was found to revert both of these to previous levels. Additionally, a method of post-processing was assessed to determine its effect on the character of the nanomaterials produced. Post-processing by acid quenching affected the structure, morphology and porosity of the silica produced. These results and on-going research will help us understand the correlation between manufacturing parameters, nanomaterials properties and their performance –a key to de novo design of novel materials. Designs of industrial scale systems for both the existing process and the bioinspired process were prepared and their detailed economic feasibility confirmed green manufacturing as a promising alternative.3Furthermore, the green process was estimated to reduce the manufacturing carbon footprint by over 90%, mainly by reduced energy requirements in the silica formation reactions, while enabling better control and tailorability of nanomaterials properties. References: 1. Patwardhan, S.V. Biomimetic and bioinspired silica: recent developments and applications. Chem. Commun., 2011, 47, 7567-7582.

2. Patwardhan, S. V. and Perry, C. C. Synthesis of Enzyme and Quantum Dot in Silica by Combining Continuous Flow and Bioinspired Routes. Silicon, 2010, 2, 33-39.

3. Drummond, C., McCann, R. & Patwardhan, S. V. A Feasibility Study of the Biologically Inspired Green Manufacturing of Precipitated Silica.Chem. Eng. J., 2014, 244, 483-492.

30

P2: Origins of Transition Metal Ordering in Ln 2O2MSe2-type Layered Oxychalcogenides

Poster contribution

Chris M. Ainsworth,1 Chun-Hai Wang,1 Hannah E. Johnston,1,3 Emma E. McCabe,1,3 Matthew G.

Tucker,2 John S. O. Evans1

1Department of Chemistry, University Science Site, Durham University, South Road, Durham, UK, DH1 3LE 2ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory,

Harwell, Oxford, Didcot, UK, OX11 0QX 3H. Johnston and E. McCabe are now based at the University of Edinburgh and the University of Kent respectively.

Email: john.evans@durham.ac.uk, web site: https://community.dur.ac.uk/john.evans/index.html

A number of LnOCuCh related compounds with composition Ln2O2MSe2 (Ln = La & Ce, M =

Fe, Zn, Mn & Cd) have been reported in the literature, built from alternating layers of fluorite-like [Ln2O2]

2+ sheets and antifluorite-like [MSe2]2– sheets. They all contain divalent transition metal ions

leading to half occupancy of tetrahedral sites in the selenide layers. The ordering of the transition metals is different across all known structures: [MSe2]

2– layers can either contain MSe4 tetrahedra that are exclusively edge-sharing (E, stripe-like), exclusively corner-sharing (C, checkerboard-like), or sections of both. This work reveals the origins of this ordering by investigating a range of solid solutions. Substitution of M leads to changes almost entirely in the c parameter, perpendicular to the layers, whereas substitution of Ln leads to an approximately isotropic change in all lattice parameters. This is attributed to a relatively rigid Ln-O layer and a flexible M-Se layer, which adapts to the size demands of the Ln-O layer. Transition metal ordering is determined by the relative sizes of [Ln2O2]

2+ and [MSe2]

2– layers, and can be tuned by doping in either layer. A progressive evolving range of commensurate and incommensurate compounds are reported, with detailed structural properties for certain examples.

Figure 1. K-vector along a of 2D ZrCuSiAs-related phases in Ln2O2M1–xM’ xSe2-type solid solutions. Orange bars represent commensurately modulated transition metal ordering, shown visually to the right of the corresponding bar. Areas between the bars indicate incommensurately modulated regions.

31

P3: “Hard-Soft” synthesis of perovskite superstructures.

Poster contribution

A. M. Arevalo-Lopez1, J. A. Rodgers1, M. Senn2, F. Sher3 and J. P. Attfield1

1Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, Edinburgh EH9 3FD, Scotland

2Department of Chemistry, University of Oxford, England 3Lahore University of Management Sciences (LUMS), Lahore 54792, Pakistan

Email:aalopez@staffmail.ed.ac.uk, web site: http://www.csec.ed.ac.uk

In recent years there has been an increasing amount of interest in manipulating and tuning the

structures and physical behaviour of complex oxides by modifying their anion lattices. This has been promoted by the use of binary metal hydrides as low temperature reducing agents, thus allowing the access to unprecedented structures and unusual oxidation states, for instance as in SrFeO2.

1

We have studied the reduction of the high pressure phases SrCrO3 and CaCrO3. Low temperature

reduction of the high pressure perovskite SrCrO3 (hard-soft chemistry) allows us to obtain two new SrCrO3-δ phases (δ=0.2 and 0.25) with unusual superstructures and properties. 1 Both are re-oxidized to cubic SrCrO3 on standing air and form long-period Cr3+/Cr4+ charge-density wave which gives rise to a spin-density wave-type modulation of the magnetic moments with a long, doubled c-axis, periodicity (2c ≈ 69 Å). Reconstruction from octahedral geometry to tetrahedral environments in widely spaced (111) planes gives 15R and 6H repeat sequences for δ=0.2 and 0.25 respectively.2

CaCrO3 reduction promotes oxygen vacancy ordering along the [001]c direction and generates

two new CaCrO3-δ phases (δ=0.33 and 0.5). Both phases show alternating tetrahedral (T) and octahedral (O) layers in a OOT and OTOT sequence.3 It is remarkable that the oxygen vacancy ordering goes along the [001]c direction for the CaCrO3-δ phases in contrast with the [111]c for the SrCrO3-δ phases.

Figure 1: a) 15-layer rhombohedral structure of SrCrO2.8. b) Monoclinically distorted 6H-structure of SrCrO2.75. The layer-stacking (z-axis) directions are vertical and the repeat sequences of cubic perovskite-type (c) and reconstructed (c’) planes are shown. Charge-density wave-type variations of the formal Cr states are labelled on the Cr4+O4/Cr3.5+O6/Cr3+O6 polyhedra. c) Structures for the CaCrO3-δ series showing the repeat sequences of octahedral (O) and tetrahedral (T) layers.

1. Y. Tsujimoto, et al., Nature, 2007, 450, 1062. 2. A. M. Arevalo-Lopez, et al., Angew. Chem. Int. Ed., 2012, 51, 10791. 3. A. M. Arevalo-Lopez, et al., J. Mater. Chem. C., 2014, 2, 9364.

32

Figure 2: muSR data showing change in

depolarisation as a function of temperature

P4: Short-ranged static magnetic order in Sr2CuWO6 with frustrated Cu(II) 2D square lattice

Poster contribution

O. J. Burrows1, G. Nielsen2, R. Stewart3, M. Telling3, M. A. de Vries1

1EaStCHEM and School of Chemistry, The University of Edinburgh, Edinburgh, EH9 3JJ

2Institute Laue-Langevin, 71 Avenue des Matryrs, CS20156, France 3ISIS, STFC, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, OX11 0QX

Email:m.a.devries@ed.ac.uk, web site: http://www.chem.ed.ac.uk/staff/academic-staff/dr-mark-de-vries/

As part of a programme of study of W(VI) and W(V) double perovskites, the compound Sr2CuWO6 has been synthesised. This has rocksalt-ordered Cu(II) S = ½ and W(VI) 5d0 ions on the perovskite B sites. Cu(II) 3d9 is Jahn-Teller active, giving rise to a cubic to tetragonal structural transition below 920 °C1. This leads to a quasi-2D square lattice with competing near neighbour and further neighbour antiferromagnetic interactions between the Cu(II) spins. Heat capacity and SQUID measurements on Sr2CuWO6 show a slow release of entropy up to 100 K, representing gradual loss of spin correlations, but no sharp peaks indicating any magnetic transitions: this was thought to imply a spin liquid at low temperatures. Hence, high-resolution powder diffraction on D2B at ILL was used along with inelastic neutron scattering and µSR at ISIS to examine magnetic interactions over a range of temperatures. Neutron diffraction shows a low-temperature magnetic peak at Q = 0.7Å-1, which corresponds to a (½,½,½) antiferromagnetic ordering (in the face-centred setting of the unit cell), as also seen in the analogous compound Ba2CuWO6 by Todate et al.2 In the inelastic region of the neutron spectroscopy data, a vertical band is seen at 0.625 Å-1: this gradually becomes broader between 20 K and 35 K and remains visible up to 100 K (figure 1). µSR shows an ordering transition occurring below 25 K; in addition, polarisation drops to one-third of the t=0 value, indicating static spins from which muons decouple at high field, suggesting that the ordering of electronic spins is static and short to medium ranged – this is in agreement with recent studies by Vasala et al.3The absence of visible anomalies in bulk data is consistent with a dynamic system of correlated spins above a transition temperature, which freeze into a particular configuration below 25 K. This is a much smaller change in entropy than would be associated with the freezing of a random, dynamic system into a static ordered state.

1 S. Vasala, J.-G. Cheng, H. Yamauchi, J. B. Goodenough and M. Karppinen, Chem. Mater., 2012, 24, 2764–2774. 2 Y. Todate, W. Higemoto, K. Nishiyama and K. Hirota, J. Phys. Chem. Solids, 2007, 68, 2107–2110. 3 S. Vasala, H. Saadaoui, E. Morenzoni, O. Chmaissem, T.-S. Chan, J.-M. Chen, Y.-Y. Hsu, H. Yamauchi and M. Karppinen, Phys. Rev. B, 2014, 89, 134419.

Figure 1: INS data on Sr2CuWO6 at 20K (left) and 50K (right)

33

P5: Microwave-assisted hydrothermal synthesis of TiO2 particles for environmental processes

Poster contribution

Mauro Davide Cappelluti1,2, Duncan H.Gregory1, Xue Jin2

Schools of Chemistry1 and Engineering2, University of Glasgow, Glasgow, G12 8QQ, Scotland

Email:m.cappelluti.1@research.gla.ac.uk, web site: http:// www.chem.gla.ac.uk/staff/duncang/Group_g.html/

Application of microwaves to chemical synthesis represents an advantageous method capable

at accelerating and shortening process times. Due to the efficient and more uniform heating, microwaves proved to be effective in increasing the yield and enhancing the purity of the resulting products1. Furthermore, compared to conventional techniques, microwave provides comparable results with milder reaction conditions, leading to huge energy savings. All these factors made the application of microwave a reliable technique to produce nanostructures. 1 Integration of both multi-mode and single-mode microwave heating to well consolidate techniques such as hydrothermal synthesis have enabled the control in shape and size of a variety of nano-objects, from simple spherical nanoparticle to nanotubes. Most of all, microwaves dramatically reduced the time to achieve the hydrothermal conditions from few days to few minutes. The accelerated reaction kinetic potentially allows access to metastable phases, otherwise impossible to obtain using conventional heating methods.

In this work is presented the development of an easy, simple and “green” technique to

produce titanium dioxide (TiO2) nanoparticles. TiO2 is one of the most common and widespread commercial materials, widely used as a white pigment in several everyday use from food to paint industry. Because of its photocatalytic activity, TiO2 finds also applications in advanced technologies such as optical sensors, energy storage and, in particular, in environmental remediation and purification processes. 2

Figure 1: TiO2 microspheres obtained using acid catalysis in MW-assisted hydrothermal synthesis

Beneath the reduction of process times, microwave-assisted synthesis potentially avoids the

use of surfactants and other organic additive usually employed in shape-controlled and phase selective synthesis, relevant to achieve the best photocatalytic performances. Using acid solutions and replacing or reducing the presence of water, the very fast reaction enabled the production of spherical particle with diameter size below 1 micron made of mainly anatase with a very fine grain size [Fig.1] A potential in situ doping, necessary to shift the photocatalytic activity of TiO2 from the UV region to the visible light, would provide a further enhancement of the properties of the nanoparticles.

1. M.Baghbanzadeh, L.Carbone et al., Angew Chem. Int., 2011, 50, 11312-11359. 2. K.Liu, M.Cao et al., Chemical Review, 2014, 114, 10044-10094

34

P6: Alkyl Chain Order/Disorder Transition in Copper Carboxylate Complexes

Poster contribution

S. M. Fellows1, T. J. Prior1

1Department of Chemistry, University of Hull, Cottingham Rd, Hull, HU6 7RX, United Kingdom

Email:S.M.Fellows@2009.hull.ac.uk

The structures of some copper carboxylate paddle wheel complexes which feature pendant

amine groups have been determined. Their thermal behaviour and phase changes have also been investigated. The phase changes are shown to be associated with reordering of alkyl chains, but the chloride and bromide analogues display different behaviour.

Figure 1: The transition of one of the alkyl chains from an ordered to disordered state with an increase in temperature.

∆T

35

P7: Early Stage Crystal Growth of ZnO Spherical Particles Constructed from Radially Aligned Nanocones

Poster contribution

Heather F. Greer, Wuzong Zhou

EaStCHEM, School of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST, Scotland Email:hfg@st-andrews.ac.uk

ZnO is a wide band-gap semiconductor with a large exciton binding energy and therefore is

extensively used in electronic applications. Control of the morphology and nanostructure of ZnO has attracted considerable attention in material science in order to enhance its functional properties. 3D hierarchical assemblies of ZnO are the most interesting as they often display novel and improved properties compared to the respective individual low dimensional nanostructured materials.

Hierarchical structures were prepared according to a previously reported solvothermal method, using a mixture of ethylene glycol (EG) and water as a solvent.1,2 The concentration of ethylene glycol was found to have a large impact on the structure of the ZnO particles. Spherical particles could be prepared with 85 vol%-EG (Figure 1a-c) and 95 vol%-EG (Figure 1d-f). Although the external structures are similar, with either spherical or irregular shaped discs on the surface, stark internal differences were observed. As expected these particles with only the polar (001)-plane exposed have displayed higher photocatalytic activities compared to those with non-polar facets exposed. The internal structure of the 85 vol%-EG synthesized ZnO particles was nanocones (150-200 nm in dimension) radially aligned along the c-axis (Figure 1c) whereas a partially orientated polycrystalline core containing 5 nm sized crystallites was observed in the 95 vol%-EG prepared ZnO (Figure 1f). Characterisation of specimens with various reaction times by XRD, SEM, HRTEM and SAED has led to a proposal of their formation mechanisms.

Figure 1: Electron microscopic images of ZnO spherical particles prepared in solvothermal conditions, (a-c) 85vol%-EG and (d-f) 95 vol%-EG. (a) SEM image of a spherical particle. The inset shows a fragment of a spherical particle. (b) High resolution SEM image of the surface of a spherical particle. The arrows mark loose cones on the surface. (c) TEM image and corresponding SAED pattern showing the nanocones are radially aligned along the c-axis. (d) SEM image of a spherical particle. (e) High resolution SEM image of the surface of the particle in (d). (f) SEM image of a fractured particle displaying its core.

1. K. Matsumoto, N. Saito, T. Mitate, J. Hojo, M. Inada and H. Haneda, Cryst. Growth Des., 2009, 9, 5014.

2. N. Saito, K. Matsumoto, K. Watanabe, T. Aubert, F. Grasset, I. Sakaguchi and H. Haneda, J. Cera. Soc. Jpn., 2014, 122, 488.

36

P8: Discovery and Development of Novel Photocatalytic Perovskites

Poster contribution

H. A. Hopper, D. E. Macphee and A. C. McLaughlin

Department of Chemistry, University of Aberdeen, Meston Walk, Aberdeen, AB24 3UE

Email: r01hah13@abdn.ac.uk

Renewable sources of energy are becoming more and more attractive a prospect in the face of ever increasing oil prices. If materials can be developed which can convert electromagnetic energy from the solar spectrum (a reliable source of renewable energy) then the reliance on oil-based fuels could be lessened. The production of hydrogen via the photo-splitting of water is one particular area of interest. The red metallic oxide, SrxNbO3 was recently reported as a novel photocatalytic material by Xu et al. with its high carrier mobility being cited as a reason for its good photoactivity in visible light. The strong colour of the material is indicative of its ability to excite electrons between the bands in the structure. We have investigated the optical and electronic properties of BaMoO3 and SrMoO3 which are strongly coloured and also show metallic conductivity. These materials may also be potential photocatalysts. The materials were synthesised via traditional solid-state methods and characterised by X-ray powder diffraction and UV-vis spectroscopy. A value for the conduction band edge of the products was obtained through Mott Schottky analysis. The materials were also tested for potential photoactivity using a solar simulator. A series of materials of general formula Sr1-xBaxMoO3 were synthesised with x = 0, 0.025, 0.05, 0.075 and 0.1, to determine the effect of Ba substitution on the band gap. A miscibility gap is observed for x > 0.1. References 1. X. Xu, C. Randorn, P. Efstathiou and J.

T. S. Irvine, Nat. Mater., 2012, 11, 595-597 2. J. Kubo and W. Ueda, Mat. Res. Bull.,

2009, 44, 906-912

37

P9: Oxidative Deintercalation of Copper from Sr2MnO 2Cu2-δS2

Poster contribution

Jack N. Blandy1, Artem Abakumov2 Joke Hadermann,2 Paul Adamson,1 Harry Cohen,1 David G. Free1 and Simon J. Clarke2

1Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, UK

2Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp, Belgium

Email:jack.blandy@chem.ox.ac.uk

Sr2MnO2Cu2-δS21 is a constituent compound of the wider class A2MO2X2Ch2 (A = Sr, Ba; M = 1st row

transition metal, X = Cu, Ag; Ch = S, Se). This class consists of distinct layers of [Sr2MnO2] and anti-PbO type [Cu2-δS]. Previous work on this compound has included investigation of its potential as a Li+ ion host in batteries2 and examination of the solid solution Sr2MnO2Cu1.5S2-xSex.

3 Deintercalation of copper from this compound is being performed to examine changes in structure and magnetic/electronic properties from a change in composition. Deintercalation of copper from Sr2MnO2Cu1.5S2 was performed using I2 (in MeCN) at room temperature and the amount of iodine consumed in the reaction was found by titration. This information was extrapolated to give a copper content value, x, of 1.2.4 However, titration of iodine consumed does not account for the possibility of I2 participating in compound-destructive side reactions occurring, resulting in an underestimation of x. It has since been found that compound-destructive reactions may be suppressed by performing the deintercalation reaction at low temperatures (273 K). A range of samples, with varying copper content were produced under these conditions and their structure analysed using X-ray powder diffraction (XRPD). Three structure types have been found from this: parent, intermediate and low-copper-content structures. The parent structure phases undergo an ordering transition at ~250 K, below which superstructure peaks occur in the XRPD pattern, corresponding to ordering in the copper vacancies. When small amounts of copper have been deintercalated the parent structure is retained, with a linear relationship between unit cell volume and copper content. However, below a copper content threshold, the samples become a mixture of a structure with the lowest attainable-copper-content and intermediate structures which require further characterisation. At x = 1.33 a single phase low-copper-content sample was produced, this allowed a good characterisation of the structure and it was found to contain a modulated copper occupancy which was described with space group Xmmm(α00)00s. This structure does not appear to undergo any additional ordering transition at low temperature. 1. W. J. Zhu and P. H. Hor, Journal of Solid State Chemistry, 1997, 130, 319-321. 2. S. Indris, J. Cabana, O. J. Rutt, S. J. Clarke and C. P. Grey, Journal of the American Chemical Society, 2006, 128, 13354-13355. 3. P. Adamson, J. Hadermann, C. F. Smura, O. J. Rutt, G. Hyett, D. G. Free and S. J. Clarke, Chemistry of Materials, 2012, 24, 2802-2816. 4. P. Adamson, DPhil, University of Oxford, 2010.

38

P10: Structural and Magnetic Properties of MnxCo1-xSb2O4 Poster contribution

J. Cumby1,2, C Greaves2 1Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh, EH9 3FD, UK.

2School of Chemistry, University of Birmingham, Birmingham, B15 2TT, UK.

Email: james.cumby@ed.ac.uk

A wide range of MX2O4 compounds are known to form in the Schafarzikite structure-type

(figure 1), particularly for X = Sb. A range of magnetic structures are known, mostly antiferromagnetic (AFM) in overall spin arrangement. The structure is characterised by opposite-edge-sharing chains of MO6 octahedra (figure 1b) linked in the ab-plane by trigonal-pyramidal SbO3 units. The Sb3+ electron lone-pairs are directed into the channel formed within the structure. The magnetic interactions between M cations are much stronger along the octahedral chains than between them, due to the significantly different interaction distances (~3 Å cf. ~6 Å).

MnSb2O4 and CoSb2O4 both order AFM at low temperatures (TN = 55 K and 79 K, respectively1,2) but with different magnetic structures (figure 2): for M = Mn an A-type (ferromagnetic ab planes) structure is observed, while Co shows a C-type structure (ferromagnetic octahedral chains). Here we report the effect of mixing Mn and Co on the M site, resulting in a gradual change in magnetic structure between that of the two end-members, as well as significant changes in magnetic susceptibility. In addition, a distinct structural change is observed around x = 0.5, which we attribute to a change the Sb-O bonding associated with the increase in unit cell volume.

Figure 1: MX2O4 (Schafarzikite) structure viewed (a) approximately along [001], and (b) along [100]; M – grey octahedra, X – large blue spheres, O – red spheres.

Figure 2: MX2O4 magnetic structures viewed approximately along [110]; Red arrows – Ax magnetic order observed for e.g. MnSb2O4; Green arrows – Cz order observed for CoSb2O4.

1. H. Fjellvåg and A. Kjekshus, Acta Chemica Scandinavica Series A-Physical and Inorganic Chemistry, 1985, 39, 389.

2. B. P. de Laune and C. Greaves, Journal of Solid State Chemistry, 2012, 187, 225.

39

P11: Pd2.8Sn Nanoalloy on ZnO support – a Lead-Free Alternative to the Lindlar Catalyst with Superior Activity for the Semihydrogenation of 2-methyl-3-buyne-2-ol

Poster contribution

Shaun Johnston1, M. Grazia Francesconi1, Alex O. Ibhadon2, Nikolay Cherkasov2

1Department of Chemistry, University of Hull, Cottingham Road, Hull, HU6 7RX. 2School of Biological, Biomedical and Environmental Sciences, University of Hull, Cottingham Road, Hull, HU6 7RX.

Email: s.k.johnston@2009.hull.ac.uk, m.g.francesconi@hull.ac.uk.

Figure 1: Reaction scheme showing the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-

buten-2-ol (MBE), avoiding overhydrogenation to 2-methylbutan-2-ol (MBA).

With the aim of achieving a viable 21st century lead-free alternative to the Lindlar catalyst for the

liquid phase selective hydrogenation of acetylene alcohols, it was found that the Pd2.8Sn nanoalloy supported on ZnO (Pd2.8Sn/ZnO) offers very high activity and selectivity for the selective hydrogenation of 2-methyl-3-butyn-2-ol to 2-methyl-3-buten-2-ol in the liquid phase. Under identical reaction conditions, Pd2.8Sn/ZnO shows significantly higher activity than the state of the art Lindlar catalyst, both turn-over frequency and activity normalized by Pd content, (TOF = 137.6 s−1 compared to 79.2 s−1 in Lindlar) with no drop in selectivity. The preparation of Pd2.8Sn/ZnO is achieved using a simple one-pot polyol procedure with the addition of a capping agent (polyvinylpyrrolidone) to control the particle size distribution. TEM shows nanoparticles evenly dispersed on the support, with a size distribution of 4.06 ± 0.75 nm. Single phase Pd2.8Sn was also prepared without the ZnO support, via the polyol method. PXRD data from the unsupported nanoalloy shows that the unit cell of Pd2.8Sn is face centred cubic with the Pd and Sn atoms occupying randomly the same crystallographic position. The chemical formula was calculated from a combination of ICP and PXRD analyses.

Figure 2: TEM micrograph of Pd2.8Sn nanoparticles on ZnO with inset particle size distribution histogram, alongside the crystal structure of Pd2.8Sn.

40

P12: Microwave synthesis of LiFe1-xMn xPO4 nanostructures for use as positive electrodes in Li ion

batteries

Poster contribution

J. Vidal Laveda1, T. E. Ashton1,P. T. Baker2, M. Tucker2, H. Playford2, S. A. Corr1 1 School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, Scotland

2ISIS Pulsed Neutron and Muon Source, STFC Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom

Email: j.vidal-laveda.1@research.gla.ac.uk, web site: http://corrgroupglasgow.com/

The higher energy density exhibited by LiMnPO4 compared to its Fe analogue due to the higher Mn2+/Mn3+ redox potential than Fe2+/Fe3+ has produced a growing interest on the metal-mixed phosphates LiFe1-

xMnxPO4.1-4 Here, nanoparticles of LiFe1-xMnxPO4 (x = 0, 0.25, 0.5, 0.75 and 1) have been prepared

following a fast solvothermal microwave-assisted route and powder X-ray diffraction characterization shows phase pure materials have been obtained. Surprisingly, scanning electron microscopy (SEM) images reveal a clear change in morphology when doping LiFePO4 with increasing amounts of Mn, going from larger crystallites to thin nanowires. To fully characterise and have a better understanding of the structure-property relationship of these nanocrystalline phases, we will also present high resolution neutron scattering and neutron pair distribution function (PDF) analyses of these materials, which allow elucidation of the structure, cation distribution, presence of defects and Li content. Finally, we also include electrochemical studies and muon spin resonance (µSR) investigations in order to explore cycling performance and the Li diffusion behaviour in these series of compounds.5

Figure 1: a) Refinement of LiFePO4 PDF data from 1 to 15 Å using PDFgui b) Cycling performance of C/LiFePO4 (15% C sucrose), C black and PTFE in 60:30:10 % weight ratio between 2.2 and 4.0 V at different rates.

1. Aravindan, Gnanaraj, Lee, Madhavi, J. Mater. Chem. A, 2013, 1, 3518. 2. Amisse, Hamelet, Hanzel, Courty, Dominko , Masquelier, J. Electrochem. Soc., 2013, 160, A1446. 3. Barpanda, Djellab, Recham, Armand, Tarascon, J. Mater. Chem., 2011, 21, 10143. 4. Delacourt, Laffont, Bouchet, Wurm, Leriche,Morcrette, Tarascon, Masquelier, J. Electrochem. Soc.,

2005, 152, A913. 5. Ashton, Vidal Laveda, MacLaren, Baker, Porch, Jones, Corr, J. Mater. Chem. A, 2014, 2, 6238.

41

P13: Non-Classical Crystal Growth of MIL-68(In)

Poster contribution

Kirsty McRoberts, Wuzong Zhou

EaStChem, School of Chemistry, University of St Andrews, Fife, KY16 9ST, United Kingdom

Email:krm6@st-andrews.ac.uk

The crystal growth of materials such as zeolites is an important area to investigate, as the growth can be

complex, and a better understanding of the way in which growth occurs can lead to more efficient mechanism1. Metal organic framework structures are similar to that of zeolites- they also tend to exhibit open, porous structures. This means that it is likely that their crystal growth may also be more complex. They are also of increasing importance in industry, due both to their porous nature, and the possibility for functionalisation of the surface2. This investigation focuses on one metal-organic framework in particular- MIL-68(In). This MOF was selected as it has two different pore sizes, and a high thermal stability3.

Using the synthesis reported in the paper by Won Cho et al4, MIL-68(In) crystals were grown by a

solvothermal process. The crystal growth was studied by carrying out scanning electron microscopy on the samples, at intervals throughout the reaction process. The images obtained suggest that a hexagonal cross-sectional area is formed early on in the reaction, as this morphology was observed at each stage of the reaction investigated thus far. The variation comes in the length of the crystal, with lengths varying from 2-15 µm after one hour, increasing with reaction time to 20-80 µm after 24 h, before decreasing to 2-15µm again at 48 h. Despite the differences in crystal length, the diameter remains similar across the reaction times. There is also variation in the amount of smaller rods growing from the large rods, with initially rods of similar sizes, but progressively more long rods appear, with fewer small rods present, until 24 h have passed, at which point most of the crystals present are longer rods, with very few smaller rods growing from the surface. It is believed that the crystals grow to a hexagonal rod structure via a core-shell growth method, with the outer hexagonal tube structure grown first, followed by the crystallisation of the material inside the rod, and caps to seal the ends of the tube, to give the rod structure.

We are currently investigating the growth mechanism further, focusing on questions such as why the

length of the crystal increase until the 24 h mark, and then appear to decrease; why are there smaller crystals growing from the larger crystals; and why do these crystals appear to be less common in reactions with longer duration, but are plentiful in the final product of the synthesis.

Figure 1: SEM images showing the growth of MIL-68(In) crystals at different synthesis times: a) 3 h; b) 18 h; c) 24 h; and d) 48 h.

1. J. Yao, D. Li, X. Zhang, C. Kong, W. Yue, W. Z. Zhou, and H. Wang, Angew. Chem. Int. Ed., 2008, 47,

8397-8399. 2. U. Mueller, M. Schubert, F. Teich, H. Puetter, K. Schierle-Arndt, and J. Pastré, J. Mater. Chem., 2006,

16, 626-636. 3. J. Liu, F. Zhang, X. Zou, S. Zhou, L. Li, F. Sun, and S. Qiu, Eur. J. Inorg. Chem, 2012, 35, 5784-5790. 4. W. Cho, H. Lee, and M. Oh, J. Am. Chem. Soc., 2008, 130, 16943-16946.

42

P14: Reversed Crystal Growth of Rhombohedral Calcite

Poster contribution

K. Self, W. Z. Zhou

EaStChem, School of Chemistry, University of St Andrews, Fife, KY16 9ST, United Kingdom

Email: ks478@st-andrews.ac.uk

Calcite crystals, which appear to be single crystals, with a rhombohedral morphology have been

synthesized in the presence of two different organic structure-directing agents: chitosan and gum arabic. The crystals were analysed via scanning electron microscopy, high resolution transmission electron microscopy and powder X-ray diffraction to determine their microstructure. Study of the growth of the crystals over time revealed a non-classical growth mechanism which followed the pattern of ‘reversed crystal growth’ previously reported in other materials.1 Initially, large aggregates were formed of the biomaterials and inorganic precursor molecules. Multiple nucleation of CaCO3 occurred, forming many calcite nanocrystallites either on the surface of the aggregates (in the chitosan system) or inside the aggregates (in the gum arabic system). These nanocrystallites aggregated again to form some large polycrystalline quasi-spherical particles which underwent surface recrystallization, forming small single-crystal islands across the surface of the aggregates. These islands of single crystal joined together over time as the reaction progressed until the entire surface was covered in a thin layer of single crystal. A core–shell structure was, therefore, observed where a polycrystalline core was encased in a thin single-crystal shell. The crystallization then extended from the surface to the core, ultimately resulting in true single crystals.2

We, and others in our group, are currently investigating the non-classical crystal growth mechanisms of other materials such as metal oxides, zeolites and metal organic frameworks.

Figure 1: SEM images displaying the surface recrystallization during the growth of rhombohedral calcite crystals. First the surface is covered in tiny islands of single crystal (a) which grow larger and join together to cover first the faces (b) of the polyhedron and then the edges until the whole surface is covered (c) and the particle appears to be a perfect single crystal

1. X. Y. Chen, M. H. Qiao, S. H. Xie, K. N. Fan, W. Z. Zhou and H. Y. He, J. Am. Chem. Soc., 2007, 129, 13305.

2. A. W. Ritchie, M. I. T. Watson, R. Turnbull, Z. Z. Lu, M. Telfer, J. E. Gano, K. Self, H. F. Greer, W. Z. Zhou, CrystEngComm, 2013, 15, 10266.

43

b

P15: Solvothermal Synthesis of a Novel 3-D Indium-Sulfide framework [(H 2tren)2

2+]2[In 4S8]4-

Poster contribution

John D. Lampkin, Anthony V. Powell, Ann M. Chippindale

University of Reading, Whiteknights Campus, Reading, Berkshire, RG6 6AD, UK

Email: j.lampkin@pgr.reading.ac.uk, web site: http://www.personal.reading.ac.uk/~qf906281/

A novel 3-D indium-sulfide framework, [(H2tren)22+]2[In4S8]

4-, has been prepared

solvothermally. This new structure crystallises in the tetragonal space group I-42d (a = 12.6605(5), c = 19.4542(15) Å) and contains a framework of adamantane-like units comprised of corner-sharing tetrahedral InS4

5- primary building units. The adamantane-like units are linked by terminal sulfur atoms resulting in large pores in the structure, Figure 1. The organic counterion could not be identified in the single-crystal analysis due to a high degree of disorder. However, a combination of analytical techniques confirms that two di-protonated molecules of tren (tris(2-aminoethylene)amine) are present per unit cell. Solid-state 13C NMR (10 kHz) showed two peaks at 38.75 ppm and 55.01 ppm, which are indicative of the two different carbon environments present in the symmetrical tren molecule. There is a difference in width of the two peaks; the peak at 55.00 ppm is broader as a result of the outer carbons’ mobility, due to higher degrees of freedom. Combustion analysis (C 13.98%, H 3.98%, N 10.37%; calc.: C 14.25%, H 3.96%, N 11.08%) and thermogravimetric analysis (TGA) (28.92% weight loss; calc.: 29.29%) further support the presence of two di-protonated molecules of tren per unit cell. TGA data exhibit a two-stage weight loss: the first of 9.62% is consistent with the loss of an ethylenediamine and an ethylamine produced by the fragmentation of a H2tren cation, the second loss of 19.30% consists of a second ethylamine fragment and the second tren molecule. The powder X-ray diffraction pattern of the post-TGA product shows peaks that are broadened compared to those of the parent compound, with a high d-spacing peak at 12.208 Å indicating retention of a structure with a large unit cell dimension. EDX data confirm that the average In:S atomic ratio (1:2) in the post-TGA product is still correct for the [In4S8]

4- unit to be intact. UV-vis diffuse reflectance measurements reveal a band gap of 2.72 eV for [(H2tren)2

2+]2[In4S8]4-.

Figure 1: Views of [(H2tren)2

2+]2[In4S8]4- in different orientations showing the 3-D pore network:

A) view down a axis and B) Alternative view. Key: Red In, yellow S.

a

c c b

9.820 Å

11.051 Å

A)

B) 14.363 Å

11.199 Å

44

P16: Tilt Engineering of Spontaneous Polarisation and Magnetisation Above Room Temperature in a

Bulk Oxide Material

Poster contribution

M. J. Pitcher1, P. Mandal1, M. S. Dyer1, J. Alaria1, P. Borisov1, H. Niu1, J. B. Claridge1 and M. J. Rosseinsky1

1Department of Chemistry, University of Liverpool, Crown Street, Liverpool L69 7ZD

Email:michael.pitcher@liverpool.ac.uk

The synthesis of new multiferroics by combining switchable polarisation and spontaneous

magnetisation in a single phase material at room temperature is a major challenge in materials chemistry. Designing such materials is difficult because of the antagonistic electronic requirements of the main mechanisms producing each property: ferroelectrics such as PbZr1-xTixO3 require polar displacements of closed-shell s2 and d0 cations, while ferromagnetism requires open-shell cations.[1] Examples where these properties are combined above room temperature are very rare and in those that are known (e.g. derivatives of BiFeO3) the coupling of polarisation (P) and magnetisation (M) is weak; it is therefore important that new strategies for combining P and M at high temperatures are investigated.

One such strategy is proposed by recent theoretical work on “hybrid improper” ferroelectrics (HIFs),[2, 3] whereby inversion symmetry is broken by combining specific octahedral tilt distortions in layered (AO)(ABO3)n or cation-ordered ABO3 perovskites. We have applied the structural principles of HIF to a carefully selected parent phase with a strongly magnetic B-site sublattice, resulting in the synthesis of a new series of iron-based n = 2 Ruddlesden-Popper phases. In this series, electrical polarization and spontaneous magnetisation are induced simultaneously by the same structural distortion (an octahedral tilt); these properties are coupled (as demonstrated by a linear magnetoelectric response) and are shown to coexist at temperatures of up to 330 K.

Figure 1: (A – C) Successive octahedral tilt distortions imposed on a Fe-based n = 2 Ruddlesden-Popper phase by chemical substitution, showing structures derived from neutron powder crystallography. (D) Layer-by-layer polarisation of the polar (a-a-c+)/(a-a-c+) member illustrated in (C) showing a net polarisation.

References

1. N. A. Hill, J. Phys. Chem. B, 104, 6694-6709 (2000) 2. N. A. Benedek and C. J. Fennie, Phys. Rev. Lett., 106, 107204 (2011) 3. J. M. Rondinelli and C. J. Fennie, Adv. Mater., 24, 1961-1968 (2012)

45

P17: Computational Investigation of Barium Orthotitanate for Application in SOFCs

Poster contribution

A. J. McSloy a*, P. M. Panchmatia a, P. R. Slater b a School of Applied Science, University of Huddersfield

b University of Birmingham a* Email:u0953388@hud.ac.uk,

With the current drive towards finding a cleaner and more efficient means of producing power, solid oxide fuel cells (SOFC) offer a potential solution, and while promising, significant improvements are required before they can reach their full potential. The development of stable materials that present excellent ionic transports speeds at a reduced temperature is paramount to creation of nextgen SOFCs. This project focus on the computational investigation of barium orthotitanate (Ba2TiO4) based materials for potential applications in SOFCs. Ba2TiO4 is an interesting material as it’s one of the only cases where Ti (IV) is found to be in a tetrahedrally coordinated environment with oxygen, it is also though to belong to a relatively new class of materials that facilitate oxygen ion migration via an interstitial transport mechanism. Preliminary testing has indicated that though careful control of, lanthanum, dopant concentration fast ionic transport speeds may be achievable. This poster will focus on the modeling of barium orthotitanate, the effects of lanthanum doping, oxygen interstitials and the transport of such interstitials.

46

P18: Formation of AlSbO4 Islands via Sb-doped SnO2 thin films on R-plane Alumina substrates doped

by a thermal diffusion method

Poster contribution

William A. Gillett1, Geoffrey W. Nelson1,2, Richard Sweeney2, Robert G. Palgrave3, Russell G. Egdell1,

David J. Payne2

1. Department of Chemistry, University of Oxford, South Parks Road, Oxford, OX1 3TA, UK

2. Department of Materials, Imperial College, Exhibition Road, London, SW7 2AZ, UK 3. Department of Chemistry, University College London, Gower Street, London, WC1E 6BT, UK

Email:g.nelson@imperial.ac.uk http://payneresearch.org/

The effectiveness of a novel method of doping thin film SnO2 with Sb was studied. Sb-doped powder was applied to a heated substrate to allow diffusion from the powder into the film. XPS and XRD data show that Sb readily incorporates into SnO2 powders, but has little effect on the lattice parameters. By contrast, thermal diffusion doping of SnO2 thin film on R-plane Al2O3 lead to large changes to the lattice parameter. Such results suggest that a new film has been made whereby the dopant Sb reacts with the Al in the substrate. XPS and XRD analysis indicates that the new films are compounds with varying AlSbO4 and SnO2 composition. The Sb present in the final compound (AlSb)1-xSn2xO4 increases proportionally with the Sb % within the powder used during thermal treatment. XPS shows that when a thin film of SnO2 is present prior to thermal diffusion treatment, the Sn content in (AlSb)1-xSn2xO4 is actually lower than in the analogue without this SnO2 overlayer. This suggest that a SnO2 thin film may act as a precursor to AlSbO4 formation. A SnO2 film undergoing thermal treatment with a 9% Sb-doped SnO2 powder will form AlSbO4 at the interface. Pole Figure XRD shows that the AlSbO4 [101] plane is parallel to the [012] surface of Al2O3. AFM data shows that AlSbO4-based products are forming islands in random distribution on the underlying substrate. The formation of AlSbO4 islands on sapphire may have potential catalytic, ion-exchange, and electronic applications.

47

P19: Synthesis, Structure and Physical Properties of Co3-xNixSn2S2 (0 ≤ x ≤ 3)

Poster contribution

Panagiotis Mangelis, Paz Vaqueiro and Anthony V. Powell

Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, England

Email: P.Mangelis@pgr.reading.ac.uk

Materials of general formula A3M2X2 where A = Co, Ni, Rh, Pd, M = Sn, In, Pb, Tl and X = S, Se crystallise in the shandite structure. The shandite structure (Figure 1) is described in the space group R m where A and M(1) atoms form kagome sheets. The kagome sheets are linked by interlayer M(2) atoms in trigonal anti-prismatic sites and the sulphur atoms occupy interlayer positions capping triangular arrays of transition metal atoms.1

Figure 2: The shandite structure with the general formula A3M2X21

In an effort to explore the effects of electron-doping, we have prepared the series Co3-xNixSn2S2 (0 ≤ x ≤ 3) by the sealed tube method at high-temperatures. Powder X-ray diffraction data reveal the substitution of cobalt by nickel causes an increase of the lattice parameter a corresponding to an expansion of the kagome lattice whilst the lattice parameter c shows less variation, exhibiting a weak maximum around x = 2.5. The experimental results are supported by DFT calculations2 which show evidence for ordering of Ni and Co atoms at critical levels of substitution (x = 1, x = 2). Densification by hot pressing leads to samples with ca 98% of theoretical density, suitable for physical property measurements at high temperatures. Resistivity data indicate metallic behaviour throughout the composition range. Due to the fact that Ni has one more valence electron than Co, the electrical conductivity is increased with increasing nickel substitution. The Seebeck coefficients are negative, indicating that electrons are the main charge carriers. The electronic and lattice contributions to thermal conductivity were determined. The results show that up to x = 1 the thermal conductivity of Co3-xNixSn2S2 remains almost constant, whilst the subsequent increase may be associated with the increased electronic contribution. Based on these measurements the figure-of-merit, ZT, has been determined for all members of the series.

1. J. Corps, P. Vaqueiro and A.V. Powell, J. Mater. Chem. A, 1, 6553, (2013), 2. A. Aziz, R. Grau Crespo, A. V. Powell and P. Vaqueiro, unpublished results.

48

P20: Hydrogen generation from ferrosilicon Poster contribution

P. Brack1, S. E. Dann1, K. G. U. Wijayantha1

1Department of Chemistry, Loughborough University, Loughborough LE11 3TU, UK

Email:p.brack@lboro.ac.uk

The search for alternative sources of energy to complement or replace fossil fuels is well underway. Hydrogen is one of the more promising options, given its large amount of chemical energy per unit mass (142 MJ kg-1)1 and the benign nature of its combustion product, water. However, due to its low density, the storage and transportation of useful quantities of hydrogen gas is problematic as it must be heavily compressed. Compressed gases must be stored in heavy steel containers, partially nullifying the benefit in terms of high gravimetric energy density of using hydrogen in the first place. Alternatively, hydrogen can be stored in cryogenic containers, but these are costly and accumulate considerable ‘boil off’ losses. Both of these approaches are also hazardous and present considerable risks to the user and the public at large. Hence for the deployment of hydrogen in vehicular and portable application to be viable, alternative storage methods must be developed. A particularly attractive approach is that of chemical hydrogen storage materials, which release their hydrogen when required by means of a chemical reaction. This is far from a new approach. Indeed, chemical hydrogen storage materials were being efficiently utilized a century ago to provide hydrogen to fill Zeppelins. The material of choice for this was ferrosilicon. Whilst a study was published some 85 years ago on the hydrogen generation properties of ferrosilicon, the role of iron was not investigated.2 By the use of techniques such as XRD, XPS and EDX, we have elucidated the role of iron in hydrogen generation reactions of ferrosilicon, and can thus evaluate the efficacy of hydrogen production from ferrosilicon in the context of more recently investigated chemical hydrogen storage materials.

Figure 1: A US Navy Zeppelin

References:

1. L. Schlapbach and A. Züttel, Nature, 2001, 414, 353. 2. E. R. Weaver, J. Ind. Eng. Chem., 1920, 12, 232.

49

P21: Synthesis, Structure and Conductivity studies of co-doped ceria: CeO2−−−−Sm2O3−−−−Ta2O5 (Nb2O5) solid solution

[Poster contribution]

P. P. Sahoo, J. L. Payne, M. Li, J. B. Claridge, and M. J. Rosseinsky

Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, U.K.

Email:ppsahoo@liverpool.ac.uk, web site: http://www.liv.ac.uk/chemistry/research/rosseinsky-group/

One of the most widely studied families of oxide ion conductors are fluorite related materials. CeO2 with a

cubic fluorite structure, when doped with a cation of lower valency displays oxide ion conductivity due to formation of vacancies.1 The doping of Sm3+ ions among rare earth oxides and Ca2+

ions among alkaline earth oxides provides the best electrical conductivity.2 There are several examples where these doped cerias have been co-doped with further cations in order to enhance the oxide ion conductivity. For e.g. the oxide ion conductivity of the Nd/Sm, Ca/Sm co-doped ceria displayed higher electrical conductivity than the singly doped cerias.3-4 In the literature, the co-dopants are mostly divalent or trivalent cations. There are very few studies where ceria is co-doped with trivalent and penta(hexa)valent cations. The solid solubility of Nb2O5/Ta2O5

in CeO2 is

low.5-6 In this study, we have explored the phase diagram of the

CeO2−Sm2O3−Ta2O5(Nb2O5) system for isolating new compositions for the possible application as electrolytes in SOFCs; as there were no systematic studies of the Ce−Sm−Ta(Nb)−O system in the literature. We report the synthesis, structure and oxide ion conductivity of a new series of Sm and Ta/Nb co-doped ceria compounds for the first time.7

Figure 1: PXRD data of several members in the series (left) and Phase diagram of the CeO2−Sm2O3−Ta2O5 system (right). The empty and filled symbols represent pure and impure phases, respectively.

1. V.V. Kharton, E.N. Naumovich, A.A. Yaremchenko and F.M.B. Marques, J. Solid State Electrochem., 2001, 5, 160.

2. H. Inaba and H. Tagawa, Solid State Ionics, 1996, 83, 1. 3. S. Omar, E.D. Wachsman and J.C. Nino, Solid State Ionics, 2008, 178, 1890. 4. S. Ramesh, V.P. Kumar, P. Kistaiah and C.V. Reddy, Solid State Ionics, 2010, 181, 86. 5. I.K. Naik and T.Y. Tien, J. Electrochem. Soc., 1979, 126, 562. 6. S. Tanase, H. Okuyama, Y. Moritoh, A. Kusunoki, M. Ippommatsu, Y. Yogome, T. Kanda, R.

Kuboshima and T. Kodama, Osaka Kogyo Gijutsu, 1994, 45, 83. 7. P. P. Sahoo, J. L. Payne, M. Li, J. B. Claridge, and M. J. Rosseinsky J. Phys. Chem. Solids, 2015, 76, 82.

50

P22: Thermoelectric properties of Co1-2xFexNixSb3 (0 ≤ x ≤ 0.5) Poster contribution

Jesús Prado-Gonjal, Paz Vaqueiro, Anthony V. Powell

Department of Chemistry, University of Reading, Reading RG6 6AD, UK

Email:j.pradogonjal@reading.ac.uk, web site: http://www.personal.reading.ac.uk/~qf906281/index.html

Compounds with the skutterudite structure (Figure 1a) have been studied extensively since they were reported as potential novel thermoelectric materials at elevated temperatures [1]. The efficiency of thermoelectric materials is expressed by the dimensionless figure of merit ZT = S2

σT/κ, where S is the Seebeck coefficient, σ and κ are the electrical and thermal conductivity, respectively, and T is the temperature. High performance requires the unusual combination of a high σ, usually associated with metallic phases, together with a high S and low κ, typical of non-metallic systems. κ consists of electron and lattice (phonon) contributions (κ = κe +κl). CoSb3 binary skutterudite possesses a large Seebeck coefficient and good electrical conductivity, resulting in large power factor (S 2

σ) values. However, thermal conductivity is too high to make it useful for the application in thermoelectric devices. One feature of CoSb3 skutterudite materials is the large number of different isostructural compositions that can be synthesized. It is possible to symmetrically substitute Co, Fe and Ni according to the formula: 2Co3+ (d6) � Fe2+ (d6) + Ni4+ (d6), which preserve the total number of electrons [2]. We have found that the substitution of the Co site by the same amount of Fe and Ni improves the thermoelectric properties. The phonon conduction can be reduced effectively, which leads to a decrease of the thermal conductivity for the Co1-2xFexNixSb3 (0 ≤ x ≤ 0.5) materials, as shown in Figure 1b.

Figure 1: a) The skutterudite structure consists of a framework of stoichiometry MX3, formed by vertex-linked MX6 octahedra, which generates large cages. b) Thermal conductivity Vs T of Co1-2xFexNixSb3 (0 ≤ x ≤ 0.5)

Co1-2xFexNixSb3 (0 ≤ x ≤ 0.5) materials have been characterized by powder X-ray diffraction in conjunction with Rietveld refinement, scanning electron microscopy - SEM - and EDS microanalysis. Seebeck coefficient, thermal and electrical conductivity measurements have also been performed and will be presented and discussed.

References:

1. J.L. Mi, X.B. Zhao, T.J. Zhu, J. Ma, Journal of Alloys and Compounds, 2008, 452, 225 2. U. Ctirad, Skutterudite-Based Thermoelectrics. In Thermoelectrics Handbook: Macro to Nano. Rowe, D.

M., Taylor & Francis, 2005, 34-1 - 34-16

a b

51

P23: Tin-based ternary photocatalysts

Poster contribution

C. Riedel 1, F. Orropeza 1, D. Slocombe 2, D. Payne 1

1Department of Materials, Imperial College London, UK 2Department of Chemistry, University of Oxford, UK

Email:c.riedel12@imperial.ac.uk, web site: http://payneresearch.org/

With an ever increasing global population, scarcity of traditional energy resources and the associated climate change threatening the future viability of a technological advanced society the need for humankind to develop renewable, sustainable energy production methods, for example solar hydrogen, is critical. Developing new materials for photocatalysis and improving the efficiency of known photocatalysts is a fundamental challenge on our path towards sustainable hydrogen production. The biggest advantage of a solar hydrogen economy would be that hydrogen is both a renewable and practically emission free energy source, able to sustain future energy demand, and at the same time an easy way to store and transport energy. One of the major disadvantages that we are facing today is that suitable semiconductor materials suffer from a lack of efficiency due to (1) wide band gaps – for the visible region and (2) charge carrier recombination. Band gap engineering for photocatalysts can be done in various ways. Incorporation of the “lone pair” of electrons would be one approach to narrow the band gap. Heavy post-transition metal oxides (Sn, Pb, Bi) exhibit these lone pair electrons [1]. The group IV elements exhibit two oxidation states, the group oxidation state N and the N-2 oxidation state. The latter – referred to in terms of the lone pair of electrons – gives rise to structural distortions in oxides such as PbO, SnO and BiVO4 [2]. The formation of the lone pair from metal s electrons (found at the top and bottom of the valence band) and oxygen p states gives rise to a narrower band gap for oxides valence bands typically dominated by the O 2p states alone [3].

Figure 1: Illustration of the energy level leading to the lone p[air formation3

We have been investigating Sn2TiO4, SnWO4 and other Sn2+ ternary oxides in terms of band structure, dominant charge carrier type and photocatalytic capability as bulk material and thin films. Using XPS the filled electronic states of different oxide materials can be investigated and our results show that the valence band of SnWO4 is influenced by the O 2p, Sn 5s and Sn 5p states. Hard x-ray photoelectron spectroscopy (HAXPES) provides further insight into the contribution of the electronic states towards the different bands by taking advantage of varying photoionization cross sections at high incident photon energies. Additionally new synthetic routes, such as microwave heating, are investigated to obtain materials unobtainable with traditional solid-state synthesis and the preliminary results will be discussed.

[1] D.J. Payne et al. Physical Review Letters 96 157403 (2006). [2] D.J. Payne et al. Applied Physics Letters 98 212110 (2011). [3] A. Walsh et al. Chemical Society Reviews 40 4455 (2011).

52

P24: Metal-Ammonia Intercalated Iron Selenide Superconductors Studied In-Situ by Powder X-Ray Diffraction

Poster contribution

Simon Cassidy1,2, Stefan Sedlmaier1, Daniel Woodruff1, Michael Drakopoulos2, Silvia Ramos-Perez3, and Simon Clarke1. 1 Department of Chemistry, University of Oxford, Inorganic Chemistry Laboratory, OX1 3QR 2 Diamond Light Source Ltd., Harwell Science and Innovation Campus, Didcot OX11 0DE 3 School of Physical Sciences, Ingram Building, University of Kent, Canterbury, CT2 7NH

Email:simon.cassidy@chem.ox.ac.uk

The synthesis of new phases of the kind AxFe2Se2 (A= alkali, alkali earth, and rare earth metals)

with Tcs ranging from 30 46 K, formed by the topotactic intercalation of A in liquid ammonia solution into the space of tetragonal FeSe was reported Ying et al. in 2012.1 Structural analysis of these materials performed by Burrard Lucas et al. showed the ‘LiFe2Se2’ structure in fact contains intercalated ammonia and amide moieties along with the alkali metal, with a refined formula of Li0.6(ND2)0.2(ND3)0.8Fe2Se2.

2

The work presented here expands on the rich structural chemistry exhibited by these metal ammonia intercalated iron selenide materials with a focus on the potassium system. Both the synthesis process and thermal decomposition of the intercalated materials have been studied in-situ using powder X ray diffraction carried out at Diamond Light Source on beamlines I12 and I11, respectively.3 These results have illuminated more than was previously observable by ex-situ analysis, leading to the characterisation of a new range of obtainable structures.

Figure 3. In-situ powder X-ray diffraction measurements, showing the intercalation of potassium and ammonia/amide into iron selenide (left), and annealing of the synthesised product showing the expulsion of ammonia above 200 °C (right).

1. Ying, T. P. et al. Observation of superconductivity at 30~46 K in A(x)Fe2Se2(A = Li, Na, Ba, Sr, Ca, Yb, and Eu). Sci. Rep. 2, 426 (2012).

2. Burrard-Lucas, M. et al. Enhancement of the superconducting transition temperature of FeSe by intercalation of a molecular spacer layer. Nat. Mater. 12, 15–9 (2013).

3. Sedlmaier, S. J. et al. Ammonia-rich high-temperature superconducting intercalates of iron selenide revealed through time-resolved in situ X-ray and neutron diffraction. J. Am. Chem. Soc. 136, 630–3 (2014).

53

P25: Solvothermal synthesis of some sodium – transition metal framework compounds for solid – state batteries

Poster contribution

I. Munaò1 and P. Lightfoot2

1, 2School of Chemistry, University of St. Andrews, St. Andrews, KY169ST, Scotland

Email:im49@st-andrews.ac.uk, web site: http://chemistry.st-and.ac.uk/staff/pl/group/

In the last few years, two concepts have become key issues in daily life: energy conversion and

energy storage. Recently the demand for large scale batteries to store the electricity in a renewable and cleaner way has become important in the energy problem. Batteries are the best way to store chemical energy and to deliver it as electrical energy. In the last decades an interest about low-cost, safe and rechargeable batteries with adequate properties (voltage, capacity, rate capability) has increased. Since they were discovered1, the best candidates for this role have been Li-ion batteries, which became the fundamental energy source for all portable electronic devices2. However the increasing cost of lithium, questions over its future availability, together with health and safety problems mean that, in the last few years, research for new materials to substitute lithium has started. The best candidate is found in sodium. In contrast to lithium, sodium is cheap and unlimited and also, from the chemistry point of view, it is the second lightest and smallest alkali metal next to lithium. Hence, rechargeable sodium ion batteries could be the promising candidates for a lot of applications3. Due to the low cost, the availability and the abundance of sodium, the interest in the synthesis of electrodes based on sodium has increased, especially using solvothermal methods.

Figure 1: General polyhedral representation of Fe2(HPO3)3 viewed along the c axis

1. M.S. Whittingham, J. Electrochem. Soc., 1976, 123.

2. C. Delmas, M. Menetrier, L. Croguennec, S. Levasseur, J.P. Peres, C. Pouillerie, L. Fournes, F. Weill, Int. J. Inorg. Mater., 1999, 1.

3. S. Komaba, W. Murata, T. Ishikawa, N. Yabuuchi, T. Ozeki, T. Nakayama, A. Ogata, K, Gotoh, K. Fyjiwara, Adv. Funct. Mater., 2011, 21 3859

54

P26: Thermoelectric Properties of the Fe and Al Substituted Chimney Ladder MnSi1.75 Poster contribution

Sonia A. Barczak1, R. A. Downie1, S. R. Popuri1, R. Decourt2,3, M. Pollet2,3 and Jan-Willem G. Bos1

1. Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, UK, EH14 4AS.

2. CNRS, ICMCB, UPR 9048, F-33600 Pessac, France.

3. Univ. Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France

Email: sb306@hw.ac.uk, web site: http://emat.eps.hw.ac.uk/

Approximately two-thirds of the world’s energy is lost as waste heat during home heating, in automotive exhaust gases and during industrial processes.1 This leads to the need for the development of efficient thermoelectric materials that can directly convert heat into electricity and vice versa. The thermoelectric efficiency of a material is determined by a figure of merit, ZT = (S2σ/κ)T. Here, the Seebeck coefficient S = ∆V/∆T is the voltage response to a temperature gradient, and σ and κ are the electrical and thermal conductivities, respectively. (T is the absolute temperature). Two series of Fe and Al double substituted MnSi1.75 chimney ladders with a valence count of 14 electrons per transition metal were prepared. Simultaneous replacement of Mn with Fe and Si with Al yielded the Mn1-xFexSi1.75-xAl x series which could be prepared for x < 0.25. The second Mn1-xFexSi1.75-1.75xAl 2x series follows the pseudo-binary between MnSi1.75 and FeAl2, and can be prepared for x < 0.1. This demonstrates that 10-15% Al can be incorporated in the Si sublattice beyond which the chimney ladder structure is unstable. Profile analysis of X-ray powder diffraction data revealed gradual changes in structure for both series. All samples showed similar temperature dependences of the Seebeck coefficient and electrical resistivity. The transport data were used to estimate the thermal band gaps and carrier concentrations which were approximately 0.38 eV and 1021 holes cm-3 for all samples. Measurement of the thermal conductivity for a Mn0.95Fe0.05Si1.66Al 0.1 sample yielded κ = 2.7 W m-1 K-1 between 300-800 K, which is comparable to MnSi1.75. A large power factor S2/ρ = 1.95 mW m-1 K-2 and promising estimated ZT = 0.5 at 820 K were observed for the x = 0.1 sample from the Mn1-xFexSi1.75-xAl x series.2

Figure 1: Temperature dependence of the estimated dimensionless figure-of-merit (ZT) of selected Mn1-xFexSi1.75-xAl x and Mn1-xFexSi1.75-1.75xAl 2x samples

1. G. J. Snyder and E. S. Toberer, Nature Materials, 2008, 7, 105-114. 2. S. A. Barczak, R. A. Downie, S. R. Popuri, R. Decourt, M. Pollet and J. W. G. Bos, submited to Journal

of Solid State Chemistry.

55

P27: Polymorphism in Vanadium OxuFluoride AVOF3 ladder systems, A = K, Rb, Cs

Poster contribution

C. Black and P. Lightfoot

1University of St Andrews, St Andrews, KY16 9ST, UK.

cb220@st-andrews.ac.uk http://chemistry.st-and.ac.uk/staff/pl/group/Group%20Page.htm

Materials exhibiting magnetic properties are of considerable interest due to their widespread use in technological applications. Materials of particular interest are those with d1 (S = ½) as, if crystallised in the correct geometry (Fig.1), they can exhibit quantum spin liquid (QSL) behaviour, showing spin fluctuation at zero K.

Fig.1. 2D kagome lattice, black dots represent metal atoms. Other geometric configurations (Fig.2) of crystal structures can lead to the display of different magnetic and physical properties that can be characterised by a variety of methods such as X-ray diffraction (both single crystal and powder), neutron diffraction and magnetic measurements.

Fig.2. 1D ladder arrangement of transition metal oxyfluoride.

Efforts to synthesise these types of materials have been steadily rising over the past few decades, and the methods that can be used to prepare these vary widely. The two main synthesis routes are Hydrothermal and Solid State, with each distinct method having subtle variations such as different solvent types and vessel shapes in Hydrothermal or inert atmospheres and furnace types in Solid State. Presented here are materials of copper and vanadium, d1 (S = ½) synthesised by these different methods, and characterised using the methods described above.

56

P28: Solvothermal Synthesis of Doped γ-Gallium Oxide Poster contribution

D.Cook1, R.I.Walton1, J. Fisher2, D. Thompsett2

1Department of Chemistry, University of Warwick, Coventry CV4 7AL 2Johnson Matthew Technology Centre, Reading, RG4 9NH

Email: daniel.cook@warwick.ac.uk

Alumina polymorphs (γ-Al 2O3 in particular) are widely employed as supports in catalysis.1 The gallia polymorphs (α, β, γ, ε, κ) are structurally analogous to the alumina polymorphs. Alpha and beta gallia have long since been characterised and studied2 and find use as catalysts in some organic reactions.3 The γ polymorph can be made via a solvothermal synthesis directly from Ga metal and only recently has its

structure been refined. 4 It has a defective cubic spinel structure with the space group . The solvothermal oxidation of gallium metal was first achieved by Kim et al.5 This synthesis was improved upon by Playford et al4 and this method yields the most crystalline form of γ-Ga2O3 as yet reported in literature, (figure 1). Since structurally analogous to the important γ-Al 2O3, doped γ-Ga2O3 may offer some interesting catalytic properties.

Figure 1 TEM image showing the crystallite size and the end-on plate shape of γ-Ga2O3

It has been shown that using the solvothermal method some first row transition metals can be doped into γ-Ga2O3 forming materials with the spinel structure MGa2O4, (M= Co, Fe, Ni and Zn). Neutron diffraction has shown that these materials can be partially defective spinels e.g Co0.973(8)Ga1.767(8)O3.752(8).

6

We present here the results regarding our attempts to dope the metals Pd, Cr and Co into γ-Ga2O3 via the solvothermal method. Materials containing GaPd2/γGa2O3 and a chromium doped gallate have been synthesized, and it has been shown that it is possible to dope cobalt directly into γ-Ga2O3. The materials have been characterised using electron microscopy, X-ray diffraction and XANES.

References: 1. Trueba, M.; Trasatti, S. P. Eur. J. Inorg. Chem., 2005, 3393. 2. R. Roy, V. G. Hill, E. F. Osborn, J. Am. Chem. Soc. 1952, 74, 719 3. Zheng, G. Hua, W. Yue, Y. Gao, Z. J. Catal 2005, 232, 143 4. Playford, H. Y., Hannon, A. C., Barney, E. R. & Walton, R. I., Chem.Eur. J., 2013, 19, 2803 5. Kim, S.-W.; Iwamoto, S.; Inoue, M. Ceram. Int., 35, 2009, 1603 6. Playford, H. Y.; Hannon, A. C.; Tucker, M. G.; Lees, M. R.; Walton, R. I. J. Phys. Condens. Matter 2013, 25, 454212

57

P29: Phase controlled synthesis of SnSe and SnSe2 hierarchical nanostructures made of single crystalline ultrathin nanosheets

Poster contribution

Parthiban Ramasamy1, 2, Palanisamy Manivasakan1, and Jinkwon Kim1

1Department of Chemistry and GETRC, Kongju National University, Kongju, 314-701, Republic of Korea 2School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, Scotland

Email:jkim@kongju.ac.uk;ilikeapj@gmail.com

The electronic and optoelectronic properties of tin selenide nanostructures are of great interest for

application in energy conversion and storage devices. Despite the great progress has been achieved in nanoparticle synthesis, controlling the crystal phase in tin selenide nanostructures remains a challenge. Herein, we present a simple solvothermal approach for the phase controlled synthesis of SnSe and SnSe2 hierarchical nanostructures (HNs). SnSe HNs has been prepared by reacting SnCl4 and SeO2 under solvothermal condition using oleylamine as solvent. By adding calculated amount of 1-dodecanethiol (1-DDT) to the reaction mixture the crystal phase can be tuned from SnSe to SnSe2. The obtained HNs were comprised of single crystalline thin nanosheets with thickness in the range of 7-12 nm. SnSe and SnSe2 HNs showed good electrocatalytic activity in the redox reaction of the I-/I3

- shuttle. Dye sensitized solar cells (DSSCs) employing SnSe and SnSe2 HNs as counter electrodes showed photovoltaic performances similar to the device made with conventional platinum (Pt) counter electrode.

Figure 1: Schematic for the phase controlled synthesis of tin selenides.

1. P. Ramasamy, P. Manivasakan, and J. Kim CrystEngComm., 2014, DIO: 10.1039/C4CE01868K.

58

P30: Hydrofluorothermal synthesis of titanium fluorophosphates and fluorosulphates Poster contribution

K.L.Marshall and M.T.Weller

Department of Chemistry, University of Bath, Bath BA2 7AY, UK Email:K.Marshall@bath.ac.uk

Hydrofluorothermal methods have been developed to synthesise both lithium and sodium transition metal fluorophosphates and fluorosulfates. Fluorine substitution into phosphate and sulfate battery cathode materials is a desirable attribute as it should lead to higher cell potentials.1 This chemistry has been previously explored for iron, manganese, cobalt and vanadium and numerous new compositions and structures reported.2,3,4 Recent work has progressed to the inclusion of titanium into such systems.5 Results to be presented here describe new titanium-based structures obtained from high fluoride-content syntheses including K2Ti2F2(H[PO4]2), Ti(HPO4)(PO3F), [Imidazole-H][Ti3F2(PO3F)(PO4)3] (shown below in Figure 1) and Li2TiF2(SO4)2.

Figure 1: Crystal structure of compound IV, [Imidazole-H][Ti3F2(PO3F)(PO4)3], viewed down the c-axis (left) and a-axis (right). Titanium octahedra in pale blue; PO3F/PO4 tetrahedra in grey; oxygen atoms in red,

fluorine atoms in green hydrogen atoms in pale pink and disordered C/N atoms in black. The unit cell is represented by solid black lines.

1. Melot, B. C.; Tarascon, J. M., Design and Preparation of Materials for Advanced Electrochemical Storage. Accounts Chem. Res. 2013, 46 (5), 1226-1238.

2. Armstrong, J. A.; Williams, E. R.; Weller, M. T., Fluoride-rich, hydrofluorothermal routes to functional transition metal (Mn, Fe, Co, Cu) fluorophosphates. Journal of the American Chemical Society 2011, 133 (21), 8252-8263.

3. Armstrong, J. A.; Williams, E. R.; Weller, M. T., Manganese(III) fluorophosphate frameworks. Dalton Trans. 2013, 42 (6), 2302-2308.

4. Wang, Q.; Madsen, A.; Owen, J. R.; Weller, M. T., Direct hydrofluorothermal synthesis of sodium transition metal fluorosulfates as possible Na-ion battery cathode materials. Chemical Communications 2013, 49 (21), 2121.

5. Sun, F. H.; Wang, R.; Jiang, H.; Zhou, W. L., Synthesis of sodium titanium phosphate at ultra-low temperature. Res. Chem. Intermed. 2013, 39 (4), 1857-1864.

59

P31: Synthesis, Structure and Thermoelectric Properties of the of the Ti1-xVxCoSb1-xSnx Half-Heusler Alloys

Poster contribution

Maryana Asaad,1 Ronald I. Smith2 and Jan-Willem G. Bos1 1 Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and

Physical Sciences, Heriot-Watt University, Edinburgh, UK, EH14 4AS.

2 ISIS Facility, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, UK, OX11 0QX

Email: ma963@hw.ac.uk; Website: http://emat.eps.hw.ac.uk/ Half-Heusler compounds based on XNiSn and XCoSb (X = Ti, Zr, Hf) are promising n- and p-type thermoelectric materials for use at intermediate temperatures (300-500 °C).1 They are characterised by a favourable combination of large Seebeck coefficients (S) and low electrical resistivities (ρ), leading to large power factors (S2/ρ) but also have relatively large thermal conductivities (κ), which limit the thermoelectric figure of merit, ZT = S2T/ρκ to values near one. Here we report on the solid solution between TiCoSb and the hypothetical 18e- compound VCoSn, which has been theoretically investigated,2 and was reported in a proceedings paper3 but has never been convincingly isolated. A series of Ti1-xVxCoSb1-xSnx (0 ≤ x ≤ 1) compounds was prepared via solid state reaction. Rietveld analysis of X-ray powder diffraction data suggested the formation of solid solution up to x = 0.43. For larger x values a dominant Co2VSn Heusler phase was observed, demonstrating that the half-Heusler VCoSn cannot be prepared using solid state reactions. Neutron powder diffraction was used to confirm the simultaneous substitutions of Ti by V and Sb by Sn for a nominal x = 0.2 sample. Variable temperature Seebeck and electrical resistivity measurements reveal n-type conduction and improved power factors for the substituted samples, although the overall magnitudes remain small (S2/ρmax = 0.5 mW m-1 K-2

at 723 K for a y = 0.2 sample).

Fig.1. Cubic lattice parameter for the Ti1-xVxCoSb1-xSnx series illustrating the formation of a solid solution up to x =

0.43. 1. T. Graf, C. Felser and S.R. Parkin. Progress in Solid State Chemistry, 2011, 39, 1; J.W.G. Bos and R.A.

Downie. Journal of Physics: Condensed Matter, 2014, 26, 433201. 2. M. Hichour et al. Journal of Physics and Chemistry of Solids, 2012, 73, 975. 3. C.S. Lue et al. IEEE Transactions on Magnetics, 2001, 37, 2138.

60

P32:Luminescence in undoped CaYAl3O7 nanopowders produced via the Pechini Method [Poster contribution]

Giordano F. da Cunha Bispo1, Adriano Borges Andrade1, Mário E. Giroldo Valerio1 1Department of Physics, Federal University of Sergipe, São Cristóvão-SE, Brazil

Email:gfredericoc@gmail.com, megvalerio@gmail.com

CaYAl3O7 has been studied because it exhibits luminescence properties when doped with rare earth ions1, 2, 3. This material has been produced via state solid reaction and combustion synthesis (SHS)1, 2. This work has as an objective the production of CaYAl3O7 nanopowders by Pechini routes followed by studying its properties. Studies of conditions for calcination showed than 1000ºC/2h is the condition for produced material. Various samples were produced and all sample with the CaYAl3O7 majority phase present one band radioluminescence in blue region. The morphological analysis showed particles with irregular size and shape and some have nanometric size. Photoluminescence (PL) studies were carried out by exciting samples in the range from near-ultraviolet (NUV) to vacuum ultraviolet (VUV).The measurements in the VUV region presented a excitation broadband extending from 7.3 eV to ~ 13.5 eV and an absorption band extending from ~ 6.4 eV to ~ 13 eV. This band was attributed to band to band transitions in the material. The result estimated that the gap energy is between 6.4eV and 7.3eV. The emission spectrum shows one band with maximum at 2.77 eV (447 nm). This emission could be assigning to F and F+ centres present in the material 4, 2. The excitation spectrum in the UV region showed a band between 3.85 eV and some energy in the region 6.5 eV-7.3 eV. The band excitation could be the overlap of other bands with similar intensity that are extended due to the influence of symmetry and crystal field where the F centres are located. The absorption bands in CaYAl3O7 are between 3 eV and 5.5 eV. They have behaviour similar to the bands found in the literature on the luminescence of the F and F+ centres 5. This information indicates that the F and F + centres may be responsible for the intrinsic luminescence of CaYAl3O7.

Acknowledgments: we thank CAPES, FINEP, FAPITEC-SE, LNLS, CMNano-UFS for funding.

2 3 4 5 6 7 8 9 10 11 12 13

0

200

400

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800

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435nm2.85eV A

bso

rptio

n(u

.a.)L

um

ines

cen

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.a.) 9.42eV

6.42eV

VUV Excitation UV-Vis Excitation Emission (Exc. 9.42eV)

CaYAl3O7 Spectra

Energy(eV)

5.08

eV

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eV

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9.42eV8.81eV

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Figure 1: Emission, excitation and absorption spectrum of CaYAl3O7

1. Zhang, H. et al, 2011 Electrochemical and Solid-State Lett. 14 J76-J80 2. Singh, V. et al, 2011 J. Fluorescence 21 313–320 3. Yamaga, M.et al, 2013 J. of Ceramic Processing Research 14 s52-s56 4. Zorenko, Y. et al, 2010 Materials Science and Engineering 15 012060

5. Henderson, B. et al, 1969 Physical Review Lett. 183 826-831

61

P33: Incommensurate layered oxychalcogenide Ce2O2MnSe2 and a simple commensurate case (Ce0.78La0.22)2O2MnSe2

Poster contribution

Chun-Hai Wang1, Chris M. Ainsworth1, Dong-Yun Gui1, Emma E. McCabe1, 3, Matthew G. Tucker2, Ivana R. Evans1 and John S. O. Evans1*

1Department of Chemistry, University Science Site, Durham University, South Road, Durham, UK, DH1 3LE 2ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory,

Harwell, Oxford, Didcot, UK, OX11 0QX 3School of Physical Sciences, University of Kent, Canterbury CT2 7NH, United Kingdom

Email: john.evans@durham.ac.uk, web site: https://community.dur.ac.uk/john.evans/index.html

Layered oxychalcogenide (Ce1-xLax)2O2MnSe2 (x = 0 - 0.7) samples were prepared by solid state

reactions and their crystal structures were determined using XRD and powder neutron diffraction (PND)

data. They show a (3+1)D modulated structure with the (3+1)D superspace group Cmme(α0 )0s0 [67.12]

and not the disordered structure reported1. The structure contains alternating stacked layers of [Ce1-xLaxO2]2+

and [MnSe2]2-. The occupancy of Mn is strongly modulated which comes from the different ideal lengths of

Ce/La-O and Mn-Se bonds. Within the [MnSe2]2- layers, the ordering pattern is a mixture of corner-sharing

and edge-sharing MnSe4 tetrahedra due to the modulation. In Ce2O2MnSe2 α = 0.158(1) but the modulation vector can be controlled by partially substituting Ce3+ is for larger La3+; a simple commensurate case with α ≈ 1/6 was obtained for (Ce0.78La0.22)2O2MnSe2. Using the supercell approximation, the 3D space structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2 were constructed. The magnetic structures of Ce2O2MnSe2 and (Ce0.78La0.22)2O2MnSe2 at 30K were obtained from PND refinement. In (Ce0.78La0.22)2O2MnSe2, Mn2+ shows antiferromagnetic (AFM) magnetic ordering at temperatures lower than ~150 K and Ce3+ shows AFM magnetic ordering at temperature lower than ~ 70 K. These lead to a complex χmol – T curves from SQUID measurements. The activation energy of charge carrier in the grain and grain boundary of Ce2O2MnSe2 pellet is 0.41(1) and 0.37(1) eV from RT to 170 °C, respectively.

Figure 1: Supercell structure and ordering pattern of [MSe2]2- layers in Ce2O2MnSe2 and (Ce0.22La0.78)2O2MnSe2.

“C”: corner-sharing; “E”: edge-sharing.

1. Ijjaali, I.; Mitchell, K.; Haynes, C. L.; McFarland, A. D.; Van Duyne, R. P.; Ibers, J. A. J. Solid State Chem. 2003, 176, 170.

62

P34: Steam Reforming of Methane on Yttria-stabilsed Zirconia – a DFT Study

Poster contribution

D. Chaopradith1, C.R.A Catlow1

1Department of Chemistry, University College London, London WC1H 0AJ, England

Email: dominic.chaopradith.13@ucl.ac.uk

Aliphatic hydrocarbons are major feedstocks for a wide variety of industrial chemical processes. They undergo a variety of oxidation mechanisms in which C-H bonds are activated by oxide catalysts. Of particular interest is the use of methane as a feedstock, from natural gas, and its partial oxidation to syngas, owing to the many industrial applications of syngas, including; the Fischer-Tropsch process, methanol synthesis and hydrogen production.1 Understanding which catalyst properties determine the mechanism for C-H bond activation is essential for studying all types of oxidative conversion on oxide catalysts. The work in this project focuses on the use of yttria-stabilised zirconia as an active catalyst support. YSZ is used as a support for metallic particles due to being mechanically robust and thermally stable, as well as having been shown to be an active partial oxidation catalyst.2 The YSZ surface is studied computationally using density functional theory. A first stage in investigating the steam reforming of methane has by simulating the interaction of water with potential surface active sites on a YSZ vacuum slab surface model. Formaldehyde is thought to be a major intermediate in the catalytic partial oxidation of methane2 and understanding how it reacts with the surface and subsequently oxidizes is of great industrial interest. The most recent work of this project is concerning adsorptions of formaldehyde and the intermediates of formaldehyde oxidation on the YSZ surface.

Figure 1: Formaldehyde physisorbed on a section of the YSZ surface.

1 T. V. Choudhary and V. R. Choudhary, Angewandte Chemie International Edition 2008, 47, 1828-1847.

2 J. Zhu, M. Rahuman, J. G. van Ommen and L. Lefferts, Applied Catalysis a-General 2004, 259, 95-100.

63

P35: How long is long enough?

Poster contribution

H. Y. Playford1, M. G. Tucker1,2, R. I. Smith1 and S. Hull1 1STFC ISIS Facility, Rutherford Appleton Laboratory, OX11 0QX, UK

2Diamond Light Source Ltd, Harwell Oxford, OX11 0DE, UK

Email:hyplayford@stfc.ac.uk, web site: http://www.isis.stfc.ac.uk

The recently upgraded Polaris instrument at the STFC ISIS Facility is one of the most versatile

neutron diffractometers in the world. Five banks of detectors mounted inside a large vacuum vessel surround the sample position, providing a low background, high count rate, good d-space resolution and a large accessible range of momentum transfer (Q). These impressive credentials mean that Polaris excels at producing high-quality diffraction data from small sample volumes and in complex sample environments, and is now greatly in demand for total scattering measurements, as well.

Using Rietveld methods to extract structural information from powder diffraction data is familiar to most and is undeniably powerful. However, it is increasingly recognized that this average picture may not be sufficient to fully understand the structure of disordered, defective and/or complex systems including many of interest to the solid-state chemistry community such as battery materials, catalysts, solid electrolytes, advanced electronic materials and MOFs.1 The technique of total scattering, in which both Bragg and diffuse scattering are treated holistically, provides a bridge between local and average structure. Measured diffraction data, once carefully normalized and corrected for non-sample scattering, can be Fourier transformed to obtain the Pair Distribution Function (PDF) which can be thought of as a weighted histogram of all interatomic separations in a sample. This function can provide valuable insight into the local and medium-range order of a material, and is now commonly used for “Rietveld-like” small-box modelling, or for large-box reverse Monte Carlo (RMC) methods which aim to

produce atomistic models that are consistent with both average and local structure.2

Because local structural distortions are encoded in weak diffuse scattering signals, total scattering datasets take longer to collect than those intended solely for Rietveld refinement. The question of how long to count for is difficult to answer, as it depends on sample size and composition as well as operational constraints such as beamtime availability, and the complexity or subtlety of the effect being studied.

This poster will explore the effect of counting time on PDF data quality, drawing on recent examples from Polaris to illustrate the various types of problem that total scattering aims to answer. With increasing interest in in situ or even in operando studies, fast measurements are necessary; but can we extract meaningful information from the PDF in these circumstances? The quartz-type AlPO4 and GaPO4 systems provide ideal test cases as splitting of the nearest-neighbour M-O peak in the PDF is crucial to the understanding of their local structure. The effect of lower data quality on real-space Rietveld and RMC refinements will also be examined using data from crystalline standards.

While there can be no one answer to “How long is long enough?” this work aims to provide insight into what is possible. In most cases, total scattering experiments needn’t consist of cumbersome 12 hour measurements, nor is an enormous sample volume necessarily a requirement. It is hoped that the diversity of systems to which total scattering is applied will continue to grow, and that this in turn will lead to improvement and innovation in experiment design and data analysis.

1. C. A. Young & A. L. Goodwin, J. Mater. Chem., 2011, 21, 6464 2. H. Y. Playford, L. R. Owen, I. Levin & M. G. Tucker, Annu. Rev. Mat. Res., 2014, 44, 429

Figure 4: Design drawing of the

upgraded Polaris instrument

64

P36: Copper Chromium Oxide Delafossites For Cathode Side Applications in SOFCs

Poster contribution

Iona C. Ross1, John T. S. Irvine1

1School of Chemistry, University of St Andrews, St Andrews KY16 9ST, Scotland

Email:icr9@st-andrews.ac.uk

Web site: http://chemistry.st-and.ac.uk/staff/jtsi/group/index.html

Issues such as element sustainability, cost and durability are important concerns for materials at the cathode side of the solid oxide fuel cell1 (SOFC). Compositions which could provide a barrier material from the chromium rich steel interconnects while also being composed of high abundance elements, or with a lower volume of expensive rare earth elements, would be of interest. Delafossite type structures (A1+B3+O2) have applications as optoelectronic transparent p-type conducting oxides2, and as thermoelectrics3 devices. Delafossite copper chromium oxide, alongside compositions doped with magnesium (CuCr1-xMgxO2, x=0.05-0.3), were investigated to observe their suitability for cathode side applications in SOFCs. The compositions were found to be stable from room temperature to 800°C in air, with thermal expansion coefficients ranging from 7.5 – 10.8 × 10-6 K-1. X-ray diffraction (XRD) and scanning electron microscopy showed that the larger Mg dopant volumes introduced a secondary spinel phase (MgCr2O4) as ~0.5µm octahedral particles embedded in the delafossite surface. The conductivities of the samples were found to be between 1– 15 S cm-1 at 800°C for 50% dense compositions, with CuCr0.975Mg0.025O2 displaying the highest conductivity. Doped samples were intimately mixed with conventional electrolyte materials yttria stabilized zirconia (YSZ) and gadolinium doped ceria (GDC) before being annealed at 800°C for 10 hours in air. XRD analysis of the resulting mixtures showed a peak at 28.3° 2θ in the delafossite-YSZ pattern that might be attributed to the strongest reflection of CuZrO3. No new phase formation was seen for the delafossite-GDC XRD patterns. Research was funded by the EPSRC and H2FC Supergen Hub.

Figure 1 Scanning electron microscopy image of the surface of CuCr0.99Mg0.01O2 with octahedral particles of

the secondary phase MgCr2O4

(1) Sun, C.; Hui, R.; Roller, J. J. Solid State Electrochem. 2010, 14, 1125–1144. (2) Poienar, M.; Damay, F.; Martin, C.; Hardy, V.; Maignan, A.; André, G. Phys. Rev. B 2009, 79, 014412. (3) Ohtaki, M.; Kubo, Y.; Eguchi, K. In 17th International Conference of Thermoelectrics; Fukuoka, Japan, 1998; pp. 559–562.

65

P37: Misfit-Layered Cobaltites: a viable route to efficient thermoelectric materials

Poster contribution

Jakub D. Baran, M. Molinari and S. C. Parker

Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY, U.K. Email: j.d.baran@bath.ac.uk

Highly efficient thermoelectric (TE) materials are of extreme importance for conversion of otherwise wasted heat to electric power. The efficiency of TE is governed by the dimensionless figure of merit , where S is the Seebeck coefficient, σ is the electrical conductivity, T the temperature and κ thermal conductivity. Therefore attaining high thermoelectric power requires minimizing thermal conductivity while keeping electrical conductivity high. This situation is achievable by enhancing phonon scattering through the specific structural disorder (phonon glass) that also retains sufficient electron mobility (electron crystal) [1]. One of the most promising example of these materials is calcium cobaltite [Ca2CoO3]0.62CoO2 (CaCO) system [2]. In this work comprehensive approach merging density functional theory, Boltzmann transport equation and a first principle lattice vibration calculations is applied to investigate structural, electronic and thermoelectric properties of misfit layered cobaltites (X2CoO3)0.62CoO2, where X=Mg, Ca, Sr, Ba. It is found that size of the band gap of the systems is inversely proportional to the size of the interlayer cation. In result metallicity of the compound is increased whereas Seebeck coefficient of the compound decreases as the cations become heavier. Lattice dynamics calculations reveal that replacing Ca by heavier Sr and Ba weaken the hybridization between the substsems which favourably affects scattering of the low frequency phonons thus reducing lattice thermal conductivity of the compound. We show an alternative way to maximize thermoelectric efficiency of the misfit cobaltites by mixing cations of different masses but the same formal charge. In that way density of states around the Fermi level and phonon scattering properties of the material can be selectively modified.

1. Slack, G.A. and D.M. Rowe, CRC Handbook of Thermoelectrics. 1995. 2. Masset, A.C., et al. Phys. Rev. B, 2000 62, 166

66

P38: Crystal growth and physical properties of polar LiMP 2O7, M=Fe, Cr

Poster contribution

E. Pachoud1,2, W. Zhang1, J. Tapp1, K.-C. Liang1, B. Lorenz1, P. Shiv Halasyamani1

1Department of Chemistry and Department of Physics, TcSUH, University of Houston, USA

2School of Chemistry, CSEC, University of Edinburgh, UK

Email: elise.pachoud@ed.ac.uk

The transition metal diphosphates A1+M3+P2O7 are interesting compounds to study as their magnetic properties are ruled only by super-super exchange interactions. Moreover, when A=Li, the compound crystallizes in the polar P21 space group. The possible coexistence of ferroelectricity and magnetic ordering makes the LiMP2O7 compounds good candidates for multiferroicity.

Indeed, a magnetoelectric effect has been found on LiFeP2O7 [1]. The measurements were carried out on large single crystals obtained from the Top-Seeded Solution Growth method. The compound is antiferromagnetic with an order temperature TN=27K. It also has a weak ferromagnetic component along the polar b axis. At this temperature, a sharp peak in the pyroelectric current is observed, and is attributed to a decrease in the level of polarization below TN.

We expect similar interactions in the Cr analogue. Both polycrystalline and single crystal forms of LiCrP2O7 were synthesized [2]. Single crystal X-ray diffraction confirmed the space group is the polar P21. The compound shows an antiferromagnetic transition at TN=6K. A spin-flop transition occurs below TN and is observed at 17kOe in the M(H) measured at 2K with the field perpendicular to the a-b plane. There was no measurable effect in the pyroelectric current at TN.

[1] K.-C. Liang, W. Zhang, B. Lorenz, Y.Y. Sun, P.S. Halasyamani, C.W. Chu, Phys. Rev. B, 2012, 86, 094414. [2] E. Pachoud, W. Zhang, J. Tapp, K.-C. Liang, B. Lorenz, P.C.W. Chu, P.S. Halasyamani, Cryst. Growth Des., 2013, 13, 5473.

67

P39: Glass-like Thermal Conductivity in SrTiO3 Thermoelectrics Induced by A-site Vacancies

Poster contribution

Srinivasa R. Popuri1, E. Suard2, R. Decourt3, M. Pollet3 and Jan-Willem G. Bos1

1Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and

Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS 2Institut Laue-Langevin, Grenoble, F-38000, France

3CNRS, University of Bordeaux, ICMCB, 87 avenue du Dr. A. Schweitzer, Pessac F-33608, France

Email: s.r.popuri@hw.ac.uk; Website: http://emat.eps.hw.ac.uk/

The central challenge in the development of efficient thermoelectric materials is to unite “electron crystal” and “phonon-glass” properties. Such a material combines the favourable electronic transport of a crystalline solid with the low thermal conductivity (κ) of an amorphous glass, leading to large thermoelectric figures of merit, ZT = S2T/ρκ. Reduced SrTiO3 has a large Seebeck coefficient (S) and low electrical resistivity (ρ), leading to promising thermoelectric power factors (S2/ρ).1 Despite enormous effort through atomic substitutions and nanostructuring, the thermal conductivity of SrTiO3 has remained characteristic of a crystalline solid (κ∝1/T). Here we have used a new approach: the introduction of vacancies on the perovskite A-site through the replacement of Sr2+ by La3+. This results in a glass-like thermal conductivity state with an almost temperature independent κ = 2.5 W m-1 K-1, close to the predicted minimum for SrTiO3.

2

Figure 1: Temperature dependence of the thermal conductivity (κ) for the A-site deficient Sr1-xLa0.67x□0.33xTiO3

perovskites.

1. T. Okuda, K. Nakanishi, S. Miyasaka and Y. Tokura, Phys. Rev. B, 2001, 63, 113104. 2. S. R. Popuri, A. J. M. Scott, R. A. Downie, M. A. Hall, E. Suard, R. Decourt, M. Pollet and J.-W. G. Bos,

RSC Advances, 2014, 4, 33720.

68

P40: Structure and Electrical Properties of Ba3MoNbO8.5

Poster contribution

S. Fop1, J. Skakle1, A. C. McLaughlin1

1Department of Chemistry, University of Aberdeen, Aberdeen, AB24 3UE , Scotland (UK)

Email:r01sf12@abdn.ac.uk

Ba3MoNbO8.5 is a hexagonal perovskite derivative that belongs to the AnBn-xO3n-δ family. Thanks to

the presence of Mo6+ and Nb5+ in the ratio 1:1, this compound presents an oxygen stoichiometry directly between that of the 9R-polytype (O9) and the palmierite (O8), causing a mixed distribution of Mo/NbO4 tetrahedra and Mo/NbO6 octahedra in the system [1]. Rietveld refinement of neutron powder diffraction data shows that a hybrid structural model is formed by the superimposition of two sub-structural units that are capable of representing the entire average structure. Refinement also showed the presence of disorder in the oxygen sub-lattice, which, together with the intrinsic oxygen deficient stoichiometry of the compound, could indicate the ability of the structure to support ionic conductivity. Preliminary impedance spectroscopy measurements will be presented.

Figure 1: Proposed structural model of Ba3MoNbO8.5.

1. E. García-González, M. Parras and J. M. González-Calbet, Chem. Mater., 10, 1576 (1998).

Palmierite 9R-polytype

69

P41: Oriented mesoporous templates for supercritical fluid electrodeposition

Poster contribution

P. N. Bartlett,1 R. Beanland,2 S. A. Boden,3 A. L. Hector,1 R. J. Kashtiban,2 P. Richardson,1 C. Robertson,1 D. C. Smith,4 J. Sloan and A. Walcarius5

1 Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK 2 Department of Physics, University of Warwick, Coventry CV4 7AL, UK

3 Electronics and Computer Science, University of Southampton, Highfield, Southampton SO17 1BJ, UK 4 Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ, UK

5 LPCME, UMR 7564, CNRS-Université de Lorraine, 405 Rue de Vandoeuvre, 54600 Villers-les-Nancy, France

Email:A.L.Hector@soton.ac.uk, web site: http://www.southampton.ac.uk/chemistry/about/staff/uccaalh.page

Supercritical fluid electrodeposition (SCFED)1 takes advantage of the densities in SCFs close to

those found in conventional solvents to allow electrodeposition with some important advantages.2 These can include a wide potential window and the possibility of depositing at elevated temperatures. A key advantage is in deposition into pores where the combination of zero surface tension excellent mass transport properties have allowed deposition of metal nanowires into 3 nm pores.2 We are investigating a number of nanopore systems that are well suited to controlled nanowire growth, where the template will define both the size and orientation of any nanowires.

Pores oriented perpendicular to a conductive substrate are the obvious orientation for

electrochemical nanowire growth but control of the orientation of such pores has been difficult to achieve even in the recent past. This orientation can be achieved by application of an electric field to order a surfactant and drive condensation of a silica sol3 or by an adaptation of the Stöber method that also involves surfactant ordering at the surface.4 Both are normally best performed on indium tin oxide, which is too easily reduced to be a general electrodeposition surface. Both methods have now been adapted to titanium nitride electrodes. We will also present a number of synthesis variations and post-synthesis treatments that vary the pore volume and surface chemistry and initial nanowire deposition data.

Figure 1: A contacted TiN on silicon electrode coated with a vertically ordered mesoporous silica film

1. Complex nanostructures by supercritical fluid electrodeposition, P. N. Bartlett et al, EPSRC programme grant number EP/I033394/1.

2. P. N. Bartlett et al, Phys. Chem. Chem. Phys., 2014, 16, 9202. 3. A. Walcarius, E. Sibottier, M. Etienne, and J. Ghanbaja, Nat. Mat., 2007, 6, 602. 4. Z. Teng et al, Angew. Chem. Int. Ed., 2012, 51, 2173.

70

P42: Structure-Property Relationships in Ferroelectric LaFeO3 and Multiferroic Bi 0.5La0.5FeO3

Poster contribution

C.A.L Dixon and P. Lightfoot

EaStCHEM School of Chemistry, University of St Andrews, Purdie Building, North Haugh, St Andrews, Fife, KY16 9ST, UK

email: cald@st-andrews.ac.uk

Multiferroic materials in which both ferroelectricity and ferromagnetism are coupled are of great technological importance in emerging technologies. The cross-coupling effects in these multiferroic materials can lead to induced electric polarisation in a magnetically ordered state and vice versa.

Figure 1: Illustration showing ferroelectric properties governed by charge and magnetic properties governed by spin. Multiferroics with cross-coupling effects can show induced polarization (P) under a magnetic field (H) and induced magnetisation (M) under an electric field (E)1. BiFeO3 is the most widely published and heavily researched of the multiferroic materials known to date, however its use in applications is hindered by electrical conductivity due to thermal metastability and non-stoichiometry. Doping BiFeO3 with rare earth metals (Ln3+) at the perovskite A-site has resulted in materials with both improved thermal stability and electric properties, particularly in La0.5Bi0.5FeO3

2. In order to better understand the role of the aspherical Bi3+ at the perovskite A-site with regard to the observed magnetoelectric coupling effects, detailed structural analyses were carried out on both LaFeO3 and La0.5Bi0.5FeO3 so that a comparison of the two could be made. High-resolution neutron diffraction experiments were carried out over a wide temperature range with both structural distortions and temperature dependent phase changes being investigated. Structural refinements were performed using the GSAS software and ISODISTORT software was implemented to provide detailed analysis of the tilt and distortion modes of both materials as a function of temperature.

Figure 2: RT phase of orthorhombic LaFeO3 (left) and rhombohedral phase found at 1270 K (right) 1. A. B. Smith and X. Y. Jones, J. Magnificent Sci., 2014, 1, 2345 2. C. M. Kavanagh, R. J. Goff, A. Daoud-Aladine, P. Lightfoot and F. D. Morrison, Chemistry of Materials,

2012, 24, 4563-4571.

71

P43: Solid state synthesis of Cu2ZnSnS4 for photovoltaic application

Poster contribution

T. M. Ng1,2, A. Walsh2, P. Sheild3, M. T. Weller2 1Doctoral Training Centre, Centre for Sustainable Chemical Technologies, University of Bath, BA2 7AY, UK

2Department of Chemistry, University of Bath, BA2 7AY, UK 3Department of Electronic and Electrical Engineering, University of Bath, BA2 7AY, UK

Email:t.ng@bath.ac.uk, web site: http://www.bath.ac.uk/csct

Cu2ZnSnS4 (CZTS) is currently of considerable interest for thin film solar cell applications as they

are based use of cheap and non-toxic raw materials unlike CuInGaS2 (CIGS) and CdTe. Polycrystalline and single crystal forms of CZTS have been synthesised via a solid state reaction using a variety of conditions. Powder X-ray diffraction (PXRD) and Raman spectroscopy have been used to confirm the presence of the desired crystal phases. Particle sizes, compositions and morphologies have been characterised using scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Band gaps have been determined from solid state UV-Vis absorption spectra. The as-synthesised polycrystalline material has been ball-milled to nanometer scale for dispersion in solvents for inkjet printing. In order to understand the effect of ball milling on CZTS samples produced from a range of different grinding conditions and periods have been characterised using PXRD, Raman, SEM/EDS and UV/Vis spectroscopy .

72

P44: Bismuth-Based Group IV Ternary Oxide Photocatalysts

Poster contribution

R. J. Walker1, F. E. Oropeza1, D. J. Payne.1

1Department of Materials, Imperial College London, Exhibition Road, SW7 2AZ, London, UK

Email: r.walker13@imperial.ac.uk, web site: http://payneresearch.org/

Bismuth based pyrochlores, Bi2M2O7, have a large potential for a wide variety of applications due to the tunability of properties based on the identity of the M atom. Bismuth iridate, for example, is metallic with interesting magnetic properties and has been investigated as a oxygen evolution catalyst while contrastingly bismuth titanate possesses a band gap of 2.9 eV.1 This flexibility with in this metal oxide system highlights the importance of the characterization of this type of materials. Of the bismuth group IV ternary metal oxides with the stoichiometry of Bi2M2O7, the bismuth titanate is by far the most extensively studied with little known about the respective zirconate and hafnate materials. Much attention has been focused on the electrical properties of Bi2Ti2O7 due to its high dielectric constant and low dielectric loss.2 Other research has investigated Bi2Ti2O7 as a photocatalyst for the oxidation of organics and methanol reforming. The structure of Bi2Ti2O7 is consistently described as a pyrochlore, with until recently a bismuth deficiency, which was required to avoid a mixture of Bi4Ti3O12 and Bi2Ti2O7 from forming.3 However in 2014, Oropeza et al. have grown stoichiometric epitaxial Bi2Ti2O7 films – with the epitaxial stabilization credited with exceeding the stabilization offered by Bi vacancies.4 While the Bi2Ti2O7 is a pyrochlore, there is debate if the structure of Bi2Zr2O7 and Bi2Hf2O7 is either pyrochlore or fluorite. The pyrochlore structure can be described as a fluorite cell with a vacancy in the 8a wyckloff positions and is preferred when the A:B ratio of the ionic radii is above 1.42. The A:B ratios of ionic radii for Bi2Ti2O7, Bi2Zr2O7 and Bi2Hf2O7 are 1.70, 1.43, and 1.45 respectively, suggesting the pyrochlore structure would predominate, however V. Sharma et. al concluded Bi2Zr2O7 to have a fluorite structure.5

Pure phase powders via coprecipitation and spin-coated polycrystalline films of these three materials have been prepared with the thin films a first for Bi2Zr2O7 and Bi2Hf2O7, allowing for the first time comparison between the bismuth group IV ternary metal oxides together. We have been investigating these materials in terms of band structure via UV-vis and X-ray photoelectron spectroscopy and crystal structure. For Bi2Zr2O7 and Bi2Hf2O7 this either provides new insight into the chemical and physical properties or clarifies conflicting/variable published results. 1. K. Sardar et. al., Chem. Matter, 2012, 24, 4192–4200. 2. C. G. Turner et al, J. Am. Ceram. Soc., 2014, 97, 1763-1768. 3. A. L. Hector et. al, J. Solid State Chem., 2004, 177, 139-145. 4. F. E. Oropeza et. al., J. Mater. Chem. A., 2014, 2, 18241-18245. 5. V. Sharma et al, RSC Adv, 2013, 3, 18938-18943.

73

P45: A Solution Chemistry Approach to Epitaxial Growth and Stabilisation of Bi2Ti 2O7 Films

Poster contribution

Freddy E. Oropeza1, Ignacio J. Villar-Garcia1, Robert G. Palgrave2 and David J. Payne1.

1Department of Materials, Imperial College London, Exhibition Road, London, SW7 2BP U. K. 2Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U. K.

Email: f.oropeza-palacio@imperial.ac.uk.

Single crystalline pyrochlore Bi2Ti2O7 films has been grown in three different orientations on yttria-stabilised zirconia at temperatures as low as 600°C, by using a simple wet chemistry method based on the spin-coating technique. Contrary to free-standing powders and polycrystalline films, epitaxial single crystalline Bi2Ti2O7 is stable relative to other bismuth titanate compounds at temperature up to 900°C. A study of core X-ray photoelectron spectra shows Bi2Ti2O7 films contain an oxygen deficiency whose concentration depends on the annealing temperature. Additionally, based on low-energy ion scattering spectroscopy, it was determined that crystalline surfaces terminate in BiOx-like structures.

2θ / degrees10 20 30 40 50 60 70 80

φ / degrees

0 50 100 150 200 250

(a)

2θ / degrees10 20 30 40 50 60 70 80

φ / degrees

0 50 100 150 200 250

(b)

φ / degrees

0 50 100 150 200 250

(c)

(e) (f) (g)

(111

)

(333

)

(222

)

(444

)

(111

)

(222

)

(220

)

(440

)

(220

)

(004

)

(008

)(002

)

(004

)BTO(111)

YSZ(111)

BTO(110)

YSZ(110)

BTO(001)

YSZ(001)

BTO(113) BTO(113) BTO(113)

YSZ(113) YSZ(113) YSZ(113)

(002

)

2θ / degrees

10 15 20 25 30 35 40

(d)

(h) Bi2Ti2O7

Bi4Ti3O12

BTO

Quartz

2θ / degrees10 20 30 40 50 60 70 80

2θ / degrees10 15 20 25 30 35 40

(a to d) θ-2θ XRD patterns of Bi2Ti2O7 films deposited on (111)-, (110)- and (001)-oriented YSZ and quartz after

annealing at 900°C. Φ scans in the [113] direction of single-crystalline film and substrate for the (111)-oriented sample (e), (110)-oriented sample (f) and (001)-oriented sample (g). (h) position of the XRD diffraction peaks of the two

phases detected in the polycrystalline film deposited on quartz.

74

P46: A hexagonal perovskite polymorph Ba2InAlO 5: structure solution woes.

Poster contribution

C. Didier1, J. Claridge1, M. Rosseinsky1

1 Department of Chemistry, University of Liverpool, Liverpool, L69 7ZD (UK)

Email:chrisdid@liv.ac.uk

The composition Ba2InAlO5 was reinvestigated from the structural point of view. A different

perovskite polymorph is obtained at high temperature. The structure has been partially solved from X-ray and neutron powder diffraction. The final model, which can only be described with disorder, is thought to exhibit a mixture of structural features previously observed in other hexagonal perovskite polymorphs, but the layering hasn’t been reported before. The author will discuss the procedure and problems encountered trying to solve the structure ab-initio.

Figure 1: Stacking model of the high temperature structure of Ba2InAlO5. In the hexagonal perovskite nomenclature, the structure could be referred to as 24R.

75

P47: High voltage cathodes for Mg-ion batteries

[Poster contribution]

H. Glass1, S.E. Dutton1, C.P. Grey2

1Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE 2Department of Chemistry, University of Cambridge, Cambridge, CB2 1EW

Email:hg346@cam.ac.uk, web site: http://www.qm.phy.cam.ac.uk/

Battery technologies for storage and portable power play a critical role in the search for more

sustainable energy generation and usage. Current technology is primarily based on the development of Li-ion batteries, however safer and cheaper alternatives are a promising area of research. Both Na-ion and Mg-ion batteries are viable alternatives as in principle they allow access to abundant elements, differing chemistries and improved performance.

In the case of Mg-ion batteries the use of a divalent cation doubles the capacity achievable per ion relative to monovalent Li and Na, allowing more energy to be stored in a given volume or weight of material. Magnesium also offers better safety characteristics than lithium; Mg metal can be used as an anode material whereas Li metal has inherent issues1. Currently Mg-ion batteries are still in the early stages of development with research focusing on understanding the types of materials and chemistries that work well with the divalent ion.

This work focuses on the synthesis and electrochemical characterization of a range of magnesium transition metal borates to be used as high voltage cathodes in Mg-ion batteries. These materials are of interest due to their open structures that may facilitate Mg-ion diffusion, light weight polyanion groups that help increase capacity and voltage, and variety of structures which allow for manipulation of redox chemistry and diffusion pathways. Examples of structures containing Mg-ion channels and various oxidation state metals are given in figure 1.

Figure 1: (Left) Structure of M2B2O5 (M = Mg, Mn, Fe, Co, Ti) viewed along the a axis. There are two distinct metal

sites forming short chains linked by BO3 units. (Right) Structure of M2OBO3 (M = Mg, Mn, Fe, Co, Ti)

1. Yoo, H. D., Shterenberg, I., Gofer, Y., Gershinsky, G., Pour, N., & Aurbach, D. Energy & Environmental Science, 6:2265–2279, 2013

76

P48: Continuous Synthesis of Metal Organic Framework (MOF-5)

[Poster contribution]

Colin McKinstry1,2, Edmund J. Cussen*2, Ashleigh J. Fletcher*1, Siddharth V. Patwardhan1 and Jan Sefcik1

1 Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow, G1 1XJ, U.K

2 WESTCHEM, Department of Pure and Applied Chemistry, University of Strathclyde, 295 Cathedral Street, Glasgow, G1 1XL, U.K.

Email:colin.mckinstry@strath.ac.uk, web site: http://svplab.com/

Metal Organic Frameworks (MOF)s are one of the classes of compounds best suited to the needs for

nanoporous materials for use in fields as varied as gas storage, catalysis and medical devices. Once such MOF material is MOF-5, one of the well-studied MOF materials developed by Yaghi et al.1 in 1999. Literature shows a great deal of information on the batch synthesis of MOF-5, however for an industrially viable product to be formed, the step to continuous processing is required. Within this work we map the formation process of MOF-5 over a time-temperature space in order to optimise the reaction as well as understand the mechanisms underpinning the MOF-5 formation.2 Using this approach we were able to produce the highest purity of MOF-5 in the most efficient way. Further, we show that MOF-5 can be formed in a solvothermal continuous process, with a consistent, high yield (>80%) while maintaining the efficiency with regard to solvent and energy costs compared to many of the batch processes described in the literature. Solids outputs are analysed as a function of time showing the systems transition from producing metastable phases to high quality MOF-5 production from a continuous system that should allow for potential scale up.

1. H. Li, M. Eddaoudi, M. O'Keeffe and O. M. Yaghi, Nature 1999, 402, 276-279. 2. C. McKinstry, E.J. Cussen, A.J. Fletcher, S.V. Patwardhan, J. Sefcik, Cryst. Growth Des., 2013, 13,

5481-5486.

77

P49: Evaluation of MOF textural parameters - lessons for materials screening [Poster contribution]

C. A. McAnally1,2, E. J. Cussen1, A. J. Fletcher2

1Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XL, Scotland 2Deparment of Chemical and Process Engineering, University of Strathclyde, Glasgow, G1 1XJ, Scotland

Email:craig.mcanally@strath.ac.uk

A new metal-organic framework (MOF) in the isoreticular series [Cu(bpy-n)2(SiF6)]n, containing the

flexible organic ligand 1,2-bis(4-pyridyl)ethane (bpetha), has been analysed for its CO2 adsorption capabilities and selectivity. While other known MOFs containing rigid linkers bipy1 and bpethene2 have been measured and found to have high surface areas using conventional N2 adsorption isotherm techniques, [Cu(bpetha)2(SiF6)]n does not exhibit these traits showing very low surface area. However, analysis of the CO2 adsorption isotherm shows a relatively high uptake (2.4 mmol g-1 at 273 K) compared with commonly measured gases CH4 and N2 at 273 K.

It is suggested that [Cu(bpetha)2(SiF6)]n shows activated diffusion within micropores, which due to the low temperature and minimal interaction of N2 with the pore surface, creates limited diffusion of the gas into the accessible structure.

Often it is found that MOF materials which do not provide a sensible value for the BET surface area under N2 adsorption at 77 K are disregarded as unsuitable for further analysis. Here we suggest that more rigorous analysis is required for porous materials, so as to avoid missing other interesting structural properties which can be targeted towards specific applications.

1. S. Noro; S. Kitagawa; M. Kondo; K. Seki, Angewandte Chemie-International Edition 2000, 39, 2082-2084

2. S. D. Burd; S. Ma; J. A. Perman; B. J. Sikora; R. Q. Snurr; P. K. Thallapally; J. Tian; L. Wojtas; M. J. Zaworotko, Journal of the American Chemical Society 2012, 134, 3663-3666.

78

P50: NaFePO4 Cathodes for Sodium Batteries: Why is Olivine More Promising Than Maricite?

[Poster contribution]

Jennifer Heath, Christopher Eames, Saiful Islam

Department of Chemistry, University of Bath, Bath BA2 7AY

Email: j.heath@bath.ac.uk, web site: http://people.bath.ac.uk/msi20/

Sodium-ion batteries are currently an area of growing interest as alternatives to lithium-ion batteries, largely due to the relative abundance of sodium and their resultant cost advantages; there is potential for sodium-ion cells to become a preferable option for large-scale grid storage. Olivine NaFePO4 is a candidate material to act as a suitable cathode for sodium-ion batteries. However, unlike LiFePO4, NaFePO4 does not crystallize in the olivine structure; its most thermodynamically stable form is the maricite polymorph, but this shows poor electrochemical behavior, which is not fully understood. Olivine sodium phosphates have previously been studied using atomistic simulation techniques1, although there are no previous investigations into defect and Na conduction properties for maricite-structured materials. Here, our atomistic study of maricite NaFePO4

indicates that anti-site Na/Fe defects are the most favourable type of defect, as found in the olivine counterparts. For the olivine material, the Na migration pathway with lowest energy (0.4 eV) runs along b-axis channels. In contrast, for the maricite compound the only possible Na-ion migration pathway was found to have a high-energy barrier (1.7 eV) due to the lack of open channels within the framework structure resulting in a low rate of sodium ion diffusion.

1. R. Tripathi, S. M. Wood, M.S. Islam and L. F. Nazar, Energy Environ. Sci., 2013, 6, 2257

79

Delegate list Name Institution Stephen Badger Blue Scientific

Branton Campbell Brigham Young University

Rob Hill Bruker UK

Robert Hardy CEM Microwave Technology

Chris Ainsworth Durham University

Chunhai Wang Durham University

James Lewis Durham University

Nicola Spaldin ETH Zürich

Jan-Willem Bos Heriot-Watt University

Maryana Asaad Heriot-Watt University

Sonia Barczak Heriot-Watt University

Srinivasa Rao Popuri Heriot-Watt University

Anna Regoutz Imperial College London

Caroline Riedel Imperial College London

Chris Lawrence Imperial College London

Chris Poll Imperial College London

David Payne Imperial College London

Emily Brooke Imperial College London

Freddy Oropeza Palacio Imperial College London

Geoff Nelson Imperial College London

Matthias Kahk Imperial College London

Robert Walker Imperial College London

Stephen Skinner Imperial College London

Craig Bull ISIS Neutron and Muon facility

Fiona Coomer ISIS Neutron and Muon facility

Helen Playford ISIS Neutron and Muon facility

Matt Tucker ISIS Neutron and Muon facility

Giordano Bispo Keele University

Richard Darton Keele University

Rob Jackson Keele University

Scott Walker Keele University

Paul Brack Loughborough University

Martin Jansen Max Planck Institute for Solid State Research

Hamish Yeung National Institute of Materials Science, Japan

Michael Brogan PANalytical

Paul O'Meara PANalytical

Ali Shehu Queen Mary, University of London

Haixue Yan Queen Mary, University of London

Hangfeng Zhang Queen Mary, University of London

Lei Wang Queen Mary, University of London

Simon Rundstrom Retsch

Colin Robinson Specac

Dominic Chaopradith University College London

Emily Glover University College London

Isaac Abrahams University College London

Jeremy Cockcroft University College London

Robert Bell University College London

Robert Palgrave University College London

Satyam Ladva University College London

Siny Mathew University College London

Abbie McLaughlin University of Aberdeen

Eve Wildman University of Aberdeen

Harriet Hopper University of Aberdeen

80

Jan Skakle University of Aberdeen

Sacha Fop University of Aberdeen

Adam Dennington University of Bath

Christopher Eames University of Bath

Jennifer Heath University of Bath

Kayleigh Marshall University of Bath

Mark Weller University of Bath

Stephen Wood University of Bath

Tat Ming Ng University of Bath

Hugh Glass University of Cambridge

Sian Dutton University of Cambridge

Ivana Evans University of Durham

John Evans University of Durham

Joseph Peet University of Durham

Luiza Rosa de Araujo University of Durham

Alexander Browne University of Edinburgh

Angel M. Arevalo-Lopez University of Edinburgh

Elise Pachoud University of Edinburgh

Giuditta Perversi University of Edinburgh

Graham McNally University of Edinburgh

Hannah Johnston University of Edinburgh

J Paul Attfield University of Edinburgh

James Cumby University of Edinburgh

Mark de Vries University of Edinburgh

Oliver Burrows University of Edinburgh

Alexey Ganin University of Glasgow

Andrew McFarlane University of Glasgow

Craig Crawford University of Glasgow

Daniel Pattoni University of Glasgow

Duncan Gregory University of Glasgow

Elissa McKay University of Glasgow

Giandomenico Furnari University of Glasgow

Ihfaf Alshibane University of Glasgow

Irene Cascallana University of Glasgow

Jennifer Carroll University of Glasgow

Joachim Breternitz University of Glasgow

Josefa Vidal Laveda University of Glasgow

Justin Hargreaves University of Glasgow

Kate McAuley University of Glasgow

Marco Amores Segura University of Glasgow

Mauro Davide Cappelluti University of Glasgow

Nicholas Spencer University of Glasgow

Parthiban Ramasamy University of Glasgow

Said Laassiri University of Glasgow

Serena Corr University of Glasgow

Thomas Ashton University of Glasgow

Vibhuti Chandhok University of Glasgow

Adam McSloy University of Huddersfield

David Cooke University of Huddersfield

Pooja Panchmatia University of Huddersfield

Kellie Binder University of Hull

M. Grazia Francesconi University of Hull

Shaun Johnston University of Hull

Simon Fellows University of Hull

Christian Faulkner University of Kent

Daniel Jackson University of Kent

81

Donna Arnold University of Kent

Emma McCabe University of Kent

Laura Vera Stimpson University of Kent

Mark Green University of Kent

Rebecca Lindsay University of Kent

Reeya Oogarah University of Kent

Christophe Didier University of Liverpool

Harry Sansom University of Liverpool

John Claridge University of Liverpool

Leopoldo Enciso Maldonado University of Liverpool

Matthew Dyer University of Liverpool

Michael Pitcher University of Liverpool

Prangya Sahoo University of Liverpool

Daniel Woodruff University of Oxford

Jack Blandy University of Oxford

Mark Senn University of Oxford

Nicholas Spencer University of Oxford

Simon Cassidy University of Oxford

Yue Wu University of Oxford

Jesus Prado-Gonjal University of Reading

John Lampkin University of Reading

Panagiotis Mangelis University of Reading

Paulo Sousa Carvalho Jr University of Sao Paulo

Anthony West University of Sheffield

Andrew Hector University of Southampton

Kripansindhu Sardar University of Southampton

Cameron Black University of St. Andrews

Charlotte Dixon University of St. Andrews

Finlay Morrison University of St. Andrews

Heather Greer University of St. Andrews

Iona Ross University of St. Andrews

Irene Munao University of St. Andrews

Jonathan Gardner University of St. Andrews

Julia Payne University of St. Andrews

Katherine Self University of St. Andrews

Kirsty McRoberts University of St. Andrews

Phil Lightfoot University of St. Andrews

Colin McKinstry University of Strathclyde

Craig McAnally University of Strathclyde

Edmund Cussen University of Strathclyde

Grant Stone University of Strathclyde

John Humphreys University of Strathclyde

Stuart Beveridge University of Strathclyde

Thomas Yip University of Strathclyde

Yashodhan Gokhale University of Strathclyde

Alexander Dunn University of Warwick

Daniel Cook University of Warwick

Luke Daniels University of Warwick

Richard Walton University of Warwick

82

RSC Solid State Chemistry Group Christmas Meeting

School of Chemistry, University of Glasgow

18th

– 19th

December 2014

Thursday 18th

December 2014

13:00 Welcome

Session 1, Chair: Prof John Evans, University of Durham

13:20 Plenary speaker: Prof Martin Jansen, Max Planck Institute for Solid State Research

“Materials discovery - from atomic energy landscapes to phase diagrams”

14:00 Irene Cascallana, University of Strathclyde, “Neutron studies of the fast ionic and high temperature phase of LiBH4 stabilised by

anion substitution”

14:15 Daniel Woodruff, University of Oxford, “Control of superconductivity in layered lithium iron selenide hydroxides Li1–xFex(OH)Fe1–ySe”

14:30 Hamish Yeung, National Institute for Materials Science, Tsukuba, “Everything Changes: Probing MOF Formation in a Model System”

14:45 Branton Campbell, Brigham Young University, “The prediction and experimental observation of compositional order in binary

platinum alloys “

15:00 Coffee break, Conference Room, School of Chemistry

Session 2, Chair: Dr Sian Dutton, University of Cambridge

15:30 Plenary speaker: Dr Ivana Evans, University of Durham

“Oxide Ion Conductors for Energy Applications: Twists and Hops in the Solid State”

16:10 Craig Bull, ISIS Neutron and Muon facility, “High-pressure, high-temperature phase diagram of elpasolite La2NiMnO6, a neutron

powder diffraction study”

16:25 Emily Glover, University College London, “Effect of codopants on electronic structure of rhodium doped TiO2 & SrTiO3 single

crystals”

16: 40 Joachim Breternitz, University of Glasgow, “Cubic [Cu(NH3)6-x]Cl2 – Loss of Jahn-Teller distortion through NH3 deficiency”

16:55 Mark de Vries, University of Edinburgh, “Tungsten-bronze-like tungstate double perovskites”

17:10 AGM

18:00 Poster presentations and City of Glasgow wine reception, followed by dinner at the Hilton Grosvenor hotel

Friday 19th

December 2014

Session 3, Chair: Prof J. Paul Attfield, University of Edinburgh

9:00 Plenary speaker: Prof Nicola Spaldin, ETH Zürich

“From Solid State Chemistry to Cosmology: Studying the early universe under the microscope”

9:40 Chris Eames, University of Bath, “Ion Conduction Mechanisms in Perovskite-based Solar Cell Materials”

9:55 Laura Vera Stimpson, University of Kent, “Structural and Magnetic properties of Ca2Mn3O8”

10:10 Jonathan Gardner, University of St. Andrews, “A-site cation size effect in unfilled ferroelectric tetragonal tungsten bronzes”

10:25 Eve Wildman, University of Aberdeen, “Colossal Magnetoresistance and Magnetic Ordering in Novel Mn2+

Pnictides”

10:40 Stephen Wood, University of Bath, “Beyond Lithium-ion: Insights into Novel Phosphate Materials for Sodium-ion Batteries”

10:55 Coffee break, Woolfson Medical Building Atrium

Session 4, Chair: Dr Isaac Abrahams, Queen Mary University of London

11:30 Plenary speaker: Dr Matt Tucker, ISIS Neutron and Muon facility

“RMCProfile: a step towards complex modelling”

12:10 Kripansindhu Sardar, University of Southampton, “Mesoporous silicon nitride and silicon–transition metal nitride composites for

heterogeneous catalysis”

12:25 Luke Daniels, University of Warwick, “Total scattering studies of disordered Bi-Fe-Mn pyrochlore oxides from hydrothermal

synthesis”

12:40 Thomas Ashton, University of Glasgow, “Local structure investigations of nanomaterials for Li-ion battery applications”

12:55 Fiona Coomer, ISIS Neutron and Muon facility, “Using µSR to investigate solid state materials”

1:10 Yue Wu, University of Oxford, “In the Right Place at the Right Time: In-Situ Observation of Materials Formation”

1:25 Prize awards and closing comments