MATERIALSMATERIALS

PHYSICS RESEARCH PHYSICS RESEARCH

INSTITUTEINSTITUTE

WITS UNIVERSITYWITS UNIVERSITY

 

  

 

 

 

       

 

  

 

 

 

       

Materials research in a country whose main economy is based on ….Minerals!!!

Some History…

The establishment of the CSIR ~1950.

Prof. Nabarro comes to South Africa – Wits

The present Materials Physics Research Institute …Prof FRN Nabarro as Director. ….` originally the mechanical properties of metals, crystallography and electron microscopy, expanded to encompass nuclear magnetic and electron spin resonance, low temperature physics, optical spectroscopy and Mössbauer spectroscopy.

Theoretical solid state physics….

New developments which included ultra-low temperature physics, Brillouin and Raman laser spectroscopy and photoluminescence, theoretical studies of phonons and ultrasound, computational physics, non-equilibrium thermodynamics, magnetism, high pressure physics and …nano-materials.

Nuclear Sciences and Ion Beam Analysis (Channeling, RBS, PIXE, ERDA, TDPAD, NRA) – Ion Implantation – Diamond Physics

Materials Science and Engineering has been identified as a University Research

Thrust and Materials Science as a Faculty of Science Research Thrust.

Centre of Excellence (CoE) for Strong Materials

Members of the MPRI:

Prof. S. BhattacharyyaProf. J.D. Comins FRSSAf MASSAf Prof. T. Derry

Dr. R. M. ErasmusProf. A.G. Every FRSSAf MASSAfProf. J M KeartlandDr B A Mathe Dr M MujajiProf. D NaidooDr S.R. Naidoo Prof. E Sideras-Haddad (Director)Dr Daniel Wamwangi

Associates: Professor M J R Hoch FRSSAf MASSAf

Profesor D S McLachlan FRSSAfDr Z Chiguvare Dr S ShrivastavaDr B. Mwakikunga (CSIR)

MPRI Research Activities •Electronic Structure •Phase Transitions in Solids•Magnetic Properties•Transport properties (at millikelvin temperatures and high magnetic field and frequencies)•Elastic properties•Dynamic properties•Optical properties•Structure and Defects in Solids•Metallic Corrosion•Nanoscale Physics (nano-electronics, growth of nano-materials)•Thin film preparation and Crystal growth•Dielectric properties of composites•Crystal dislocations•Extended non-equilibrium thermodynamics•Interfaces and Interfacial Segregation in Solids•Mechanical Properties – fracture, hardness, elastic-plastic properties •Diamond Physics•Theoretical studies of phonons and ultrasound

5-Years Review: 2010-2014

165 International Publications in DoE Recognised Journals

MSc Students 24PhD Students 28 Total Postgraduate Students: 52

Experimental Facilities at the MPRI

Prof S BhattacharyyaEquipment for Quantum Transport measurementsCryogen-free completely automated physical property measurement system

Experiments and Research Facilities:

(i)Transport property measurements (Cryogenic VTI) 350 K - 0.3 K, and field up to 12 T(ii)Synthesis of nanocrystalline diamond films (Hot-filament CVD), multi-layered carbon thin films, carbon nanotubes and nanowires by pulsed laser ablation assisted CVD(iii) Characterization of Magnetic properties in low-dimensional carbon 0-12 T (VSM)

(iv) Impedance measurement up to 67 GHz in the temperature range 400 K to 4 K and magnetic fields up to 3 T(v) Microscopy/spectroscopy (SEM/AFM/STM/Optical/Raman)(vi) Combined SEM and AFM study(vii) Fabrication of nanoelectronic devices by e-beam lithography(viii) Nano-manipulation and in situ transport property measurements

•Lasers: S-P 8W argon ion laser; S-P 5W Krypton ion laser; S-P Tunable dye laser pumped by S-P 15W argon ion laser.

•Detectors: Liquid nitrogen cooled CCD; photomultiplier.

•Confocal Raman microscope with a computer controlled scanning stage for 2- and 3-D regions.

•Miniature low and high temperature microscope stages

•Furnace and low temperature cryostat.(4 - 1800 K)

•Electrochemical cell for temperature dependent corrosion studies with in-situ Raman studies.

•Diamond anvil cell for high pressure studies.

Prof J D Comins – R. ErasmusRaman and Photoluminescence Spectroscopy

Prof. D. Comins – B. MatheBrillouin Scattering Spectroscopy

Brillouin laser light scattering determines the elastic properties of materials in bulk form, thin films and coatings as a function of temperature, pressure, micro-structure, composition strain.

In order to determine the frequency spectrum of the scattered light, a high resolution and contrast pass interferometer is used.

The high precision interferometer mirrors are electronically stabilised on an electronically controlled anti-vibration stage.

Surface Brillouin scattering studies at high pressure have been carried out using a gem-anvil cell

Spectrophotometer

Cary 500 double beam spectrophotometer.Wavelength range 185 nm to 3 μm.

Studies of optical absorption, specular and diffuse reflectance of materials.

Studies of defects as a function of temperature using special cryostats and heating stages.

Deena Naidoo: Mössbauer Spectroscopy

57Fe and 197Au (gold) Mössbauer spectroscopy.

Cryogenic facilities for Mössbauer spectroscopy experiments down to 4 K.

Beamline

(57Mn+/119In* ions)

 

Implantation

Chamber

 

Mössbauer Drive

 

ISOLDE - CERN

A beam of radioactive 57Mn+ ions (half-life = 1.5 min) is produced at ISOLDE using 1.4 GeV proton-induced fission in a UC2 target. Beams of 57Mn+ are accelerated to between 40 and 60 keV and implanted into the samples.

Dr. J. Keartland:Magnetic resonance spectrometers: EPR and

NMR

Bruker Electron Magnetic Resonance

Spectrometer operable in both ContinuousWave and Pulsed modes. A Continuous Flow Cryostat enables experiments to be done in the range 2 K to 300 K. The spectrometer is being used to characterize diamonds and nanomaterials.

Pulsed Nuclear Magnetic/QuadrupoleResonance (NMR/NQR) Spectrometer.

Frequency range: 1 MHz to 200 MHz. Used to probe materials with a large range ofnuclei. In the picture shown it is operatingin zero field mode (a Nuclear QuadrupoleExperiment). A continuous flow cryostat allows for low temperature investigations.

Dr Marjorie MujajiEquipment for site-selective laser spectroscopy

- 8 K closed cycle cryostat- dye laser range 630 – 660 nm with DCM dye- double-grating scanning spectrometer 350 – 900 nm - 15W argon ion laser- cooled photon counter and photon counting electronics

Atomic Force Microscopy / Scanning Tunneling Microscopy

Various techniques are available with these two instruments:

(i) Atomic force microscope(ii) Scanning tunnelling microscope(iii) Lateral force microscope(iv) Force modulation and Phase modulation microscope(v) Magnetic force microscope(vi) Electric-field gradient microscope(vii) Scanning capacitance microscope

ACCELERATOR MASS SPECTROMETRY - AMSACCELERATOR MASS SPECTROMETRY - AMSMeasurements of isotopic ratios Measurements of isotopic ratios

As low as …. 10As low as …. 10-15 -15 !!! !!!

10Be, 14C, 27Al, 36Cl, 41Ca …..Actinides

Ion ImplantationIon ImplantationiThemba LABS / WITSiThemba LABS / WITS

• The future of materials research is unlimited: New terrific opportunities in novel materials enabled by our recent ability to manipulate matter at the atomic and molecular scales. 

• The birth of nanomaterials and nanoscience

• This size scale, which is about the same as that of biological structures, opens up a whole new world at the interface of materials and life sciences. 

MRAM chips represent one class of spintronics, in which the spins of large numbers of electrons are aligned the same way, as with a collection of toy tops all spinning clockwise on the floor.

These so-called spin-polarized electrons typically flow through some part of the device, forming a spin-polarized current like a polarized beam of light.

A second class of spintronics: Quantum Spintronics, manipulation of individual electrons to exploit the quantum properties of spin.

Quantum Spintronics could provide a practical way to carry out quantum information processing, which replaces the definite 0s and 1s of ordinary computing with quantum bits, or qubits, capable of being 0 and 1 simultaneously, a condition called a quantum superposition.