Conductivity study by complex impedance spectroscopy … · Conductivity study by complex impedance ... cell parameters were reﬁned using Celref 3.0 program ... Conductivity study

Arabian Journal of Chemistry (2015) xxx, xxx–xxx

King Saud University

Arabian Journal of Chemistry

www.ksu.edu.sawww.sciencedirect.com

REVIEW

Conductivity study by complex impedance

spectroscopy of Na3Nb4As3O19

* Corresponding author at: Laboratoire de Materiaux et

Cristallochimie, Faculte des Sciences de Tunis, Universite de Tunis

El Manar, 2092 El Manar II, Tunis, Tunisia.

E-mail address: [email protected] (S.F. Cherif).

Peer review under responsibility of King Saud University.

Production and hosting by Elsevier

http://dx.doi.org/10.1016/j.arabjc.2015.09.0011878-5352 � 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Please cite this article in press as: Cherif, S.F. et al., Conductivity study by complex impedance spectroscopy of Na3Nb4As3O193Nb4As3O19 –>. Arabian JoChemistry (2015), http://dx.doi.org/10.1016/j.arabjc.2015.09.001

Saıda Fatma Cherif a,b,*, Mohamed Faouzi Zid a, Ahmed Driss a

aLaboratoire de Materiaux et Cristallochimie, Faculte des Sciences de Tunis, Universite de Tunis El Manar, 2092 El Manar II,Tunis, Tunisiab Institut Preparatoire aux Etudes d’Ingenieurs – El Manar, Universite de Tunis El Manar, 2092 El Manar II, Tunis, Tunisia

Received 7 October 2014; accepted 7 September 2015

KEYWORDS

Three-dimensional frame-

work;

IR spectroscopy;

CI spectroscopy;

Ionic conductivity

Abstract Crystals of Na3Nb4As3O19 were synthesized by a solid-state reaction. It crystallizes in the

orthorhombic system, space group C2221 with a= 13.014(2) A, b= 24.170(3) A and c = 5.0880

(9) A. The structure can be described as a three-dimensional anionic framework containing two

kinds of tunnels parallel to [001] direction where Na+ cations are located. The ionic conductivity

was measured, on pellets of polycrystalline powders, between 573 and 893 K in the frequency range

0.01–13000 kHz through the complex impedance method. A correlation between electrical and

structural properties was also discussed.� 2015 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. This is an

open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

2. Experimental section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002.1. Polycrystalline powder synthesis of Na3Nb4As3O19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 002.2. Infrared spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

2.3. Ionic conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003. Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

3.1. Crystal structure and refinement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

urnal of

http://creativecommons.org/licenses/by-nc-nd/4.0/

mailto:[email protected]

http://dx.doi.org/10.1016/j.arabjc.2015.09.001


http://www.sciencedirect.com/science/journal/18785352


http://creativecommons.org/licenses/by-nc-nd/4.0/


2 S.F. Cherif et al.

3.2. Description of the structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

3.3. Infrared spectroscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003.4. Ionic conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 003.5. Correlation between electrical and structural properties of Na3Nb4As3O19 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

4. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 00

1. Introduction

The synthesis of compounds that contain monovalent cationsand those with tunnel or layer structures is of potential interestdue to their remarkable ionic conductivity (Daidouh et al.,

1999, 1997; Masquelier et al., 1995; Marzouki et al., 2014;Hajji and Zid, 2012; Frigui et al., 2010, 2011). In order to syn-thesize compounds of this type, we have investigated A–Nb–

As–O system (A = monovalent ion). In a previous work, wehave isolated a few novel mixed oxides (Cherif et al., 2011a,b, 2012a,b). Among these compounds, there are those which

exhibit a tunnel structure. Other cases such as K8Nb7As7O39

exhibit a layer structure where potassium cations are locatedin interlayer space (Cherif et al., 2012b).

The purpose of the present paper is to investigate the elec-

trical properties of Na3Nb4As3O19 and to establish correlationbetween its structure and physical properties.

2. Experimental section

2.1. Polycrystalline powder synthesis of Na3Nb4As3O19

All chemicals were commercially available andwere usedwithoutanypurification.A polycrystalline powder ofNa3Nb4As3O19was

synthesized by a solid-state reaction method from a stoichiomet-ric mixture of Na2CO3, As2O5 and Nb2O5. Starting materialswere mixed and ground together in an agate mortar and heated

progressively to 800 �C in porcelain crucible with intermittentcooling and re-grindings.

The powder was analyzed by X-ray powder diffraction,

using a PAN-analytical X’Pert PRO X-ray diffractometerequipped with copper anticathode (kKa = 1.5406 A). The unitcell parameters were refined using Celref 3.0 program(Altermatt and Brown, 1987) and calculated to be as:

a= 13.015(2) A, b = 24.175(4) A and c= 5.0857(1) A. The

Figure 1 Calculated and experimental powder X-ray diffraction

patterns of Na3Nb4As3O19.

Please cite this article in press as: Cherif, S.F. et al., Conductivity study by complexChemistry (2015), http://dx.doi.org/10.1016/j.arabjc.2015.09.001

powder X-ray diffraction pattern was in agreement with

single-crystal structure (Cherif et al., 2012a) (Fig. 1).

2.2. Infrared spectroscopy

The infrared spectrum of Na3Nb4As3O19 was carried out on aPerkin–Elmer FTIR Paragon 1000 PC spectrometer. Thesample was mixed with dried KBr.

2.3. Ionic conductivity

The electrical properties of the title compound have beeninvestigated on a polycrystalline sample using complex

impedance spectroscopy (CIS).Measurements were carried out in a Hewlett-Packard

4192-A automatic bridge monitored by a HP microcomputer.

The frequency/temperature ranges are 0.01–13,000 kHz/300–620 �C, respectively. Pellet of 13 mm diameter and1.66 mm thickness was prepared by pressing the powder

sample at 12 tones. Then the pellets were heated at 500 �Cfor 12 h in order to improve continuity between the grains.Silver electrodes were painted in the two faces of the pellets

with a silver paste to ensure good electrical contact.Correlation between the sample electrical behavior and its

microstructure is also discussed.

3. Results and discussion

3.1. Crystal structure and refinement

A suitable colorless single crystal with (0.35 � 0.25 � 0.16)mm3 dimensions was selected for the structure determination

and refinement. The data were collected on an Enraf-NoniusCAD-4 automatic four-circle diffractometer using Mo Karadiation (k= 0.71073 A) at room temperature. The unit-cell

Table 1 Parameters and final reliability factors of crystal

structure of the Na3Nb4As3O19 compound.

Crystal system Orthorhombic

Space group C2221Cell parameters a = 13.014(2) A

b = 24.170(3) A

c = 5.0880(9) A

Reflections collected 2166

Independent reflections 1757

Rint 0.041

R(F) 0.029

xR(F2) 0.076

impedance spectroscopy of Na3Nb4As3O193Nb4As3O19 –>. Arabian Journal of


Figure 2 Representation of: (a) infinite chains [Nb12O10]1 and (b) infinite ribbons [Nb4O18]1 in Na3Nb4As3O19.

Figure 3 Representation of the junction between chains and

ribbons in Na3Nb4As3O19.

Figure 4 Projection of the structure of Na3Nb4As3O19 along c

axis showing tunnels where Na+ cations are located.

1200 1000 800 600 4000,6

0,7

0,8

0,9

1,0

657

Tran

smitt

ance

(%)

Wave number (cm-1)

424

482

536

761856908

991 514

Figure 5 IR spectrum of Na3Nb4As3O19.

Conductivity study of Na3Nb4As3O19 3

parameters were determined and refined using a least-squaresmethod based upon 25 reflections in the range 10–15�. Theexperimental values, the final structure refinements and theconditions of intensities collection are detailed in previouswork (Cherif et al., 2012a,b).

The essential structural data are shown in Table 1.


3.2. Description of the structure

The structure of Na3Nb4As3O19 can be described from NbO6

octahedra and AsO4 tetrahedron sharing vertices. In the anio-nic framework, Nb1O6 octahedra form by sharing vertices infi-

nite chains [Nb12O10]1 running along [001] (Fig. 2a). Nb2O6

and Nb3O6 octahedra are connected by vertices to form infiniteribbons [Nb4O18]1 (Fig. 2b). The junction of these ribbons

and chains is assured by vertices via AsO4 tetrahedron(Fig. 3). It results in a three-dimensional framework withtwo kinds of tunnels parallel to the [001] direction whereNa+ cations are located (Fig. 4).

3.3. Infrared spectroscopy

To investigate the coordination environment of Na3Nb4As3-

O19, the infrared spectroscopy was carried out in the range1200–300 cm�1 and the obtained spectrum is shown in Fig. 5.

The assignment of the different vibrational bands of NbO6

and AsO4 groups based on those found in the literature (BenAmor et al., 2008; Nakamoto, 1978; Bouzemi Friaa et al.,2003; Ouerfelli et al., 2007a,b), is shown in Table 2.

3.4. Ionic conductivity

Fig. 6 shows the complex impedance spectra, Nyquist plots,reflecting the variation of the imaginary part of the complex



Table 2 Assignment of vibration fre-

quencies in Na3Nb4As3O19.

Wave number (cm�1) Assignment

424 m4(AsO4)

482 m4(NbO6)

514

536

657 m2(NbO6)

761 m3(NbO6)

856 m1(AsO4)

908 m3(AsO4)

991

Figure 7 (a) The ln(rT) versus 104/T plot. (b) The ln(fmax) versus

104/T plot, where fmax is the Z00max peak frequency.


impedance (�Z00) versus its real part (Z0) at various tempera-tures and a wide range of frequency. The impedance spectra

are characterized by the appearance of a single semicirculararc with their centers below the real axis. The measuredimpedance can be modeled as equivalent electrical circuits

comprising of a parallel combination of bulk resistance andCPE; which is the non-ideal capacitor usually known asconstant phase element (Anantha and Hariharan, 2005).

For each temperature, we determine the value of Z byZView program (ZView Version 3.1c, 1990–1997). The ionicconductivity as function of the temperature has been obtainedfrom the values of intercept of the extrapolated high-frequency

semicircles with the real axis. As a consequence, the value ofthe conductivity r governed by the relationship (1) is calcu-lated as follows:

0 20000 40000 60000 800000

10000

20000

30000

40000

460°C 440°C420°C-Z

'' (o

hm)

Z' (ohm)

Z' (ohm)0 1000 2000 3000 4000 5000

0

500

1000

1500

2000

2500

580°C 560°C 540°C-Z''

(ohm

)

0 60000 120000 1800000

30000

60000

90000

340°C320°C

300°C

-Z''

(ohm

)

Z' (ohm)

Figure 6 Complex impedance spectrum of Na3Nb4


r ¼ ðe=sÞ=Z ðX�1 cm�1Þ ð1ÞThe conductivity variation indicates an increase in conduc-

tivity with rise in temperature with a typical Arrhenius-typebehavior: linear dependence of thermal conductivity logarithmln(rT) versus 104/T (K�1) (Fig. 7a). This type of temperature

dependence of the conductivity indicates that the electricalconduction in the materials is a thermally activated process.It can be explained in accordance with the expression (2) as

follows:

0 40000 80000 1200000

20000

40000

60000

400°C380°C

360°C-Z''

(ohm

)

Z' (ohm)

0 5000 10000 15000 200000

2500

5000

7500

10000

520°C 500°C480°C-Z

'' (o

hm)

Z' (ohm)

0 500 1000 1500 20000

250

500

750

1000

620°C610°C

600°C

-Z''

(ohm

)

Z' (ohm)

As3O19 over temperature range 300 and 620 �C.



Figure 8 Variation of imaginary part of impedance (�Z00) with frequency at various temperatures.

Figure 9 A zoom of the differential scanning calorimetry curve

of Na3Nb4As3O19.

Figure 10 Dimensions of the large tunnel in Na3Nb4As3O19

structure.

Figure 11 Dimensions of the hexagonal tunnel in Na3Nb4As3-

O19 structure.



rT ¼ A0 expð�Ea=kTÞ ð2Þ

where A0 is the pre-exponential factor, Ea is the activationenergy, T is the absolute temperature and k is the Boltzmannconstant.



Table 3 Occupancies of Na+ cations.

Atoms x y z Occupancies Wyckoff

Na1 0.2677(4) 1/2 0 0.937(16) 4a

Na2 0.0494(12) 1/2 1/2 0.68(3) 4a

Na3 0.184(4) 1/2 1/2 0.092(18) 4a

Na4 0.105(7) 1/2 1/2 0.11(3) 4a

Na5 0.771(3) 0.7465(10) 0.753(13) 0.12(2) 8c

Na6 0.742(4) 0.7414(15) 0.629(18) 0.11(3) 8c

Na7 0.7659(13) 0.7594(7) 0.006(11) 0.191(16) 8c

Na8 0.7726(19) 0.7525(11) 0.892(12) 0.17(2) 8c


Fig. 8 shows the variation of the imaginary part of impe-dance with frequency (loss spectra) at different temperatures.

The spectra are characterized by the presence of peaks at aparticular frequency. As temperature increases the magnitudeof Z00 peak maxima decreases and the peak frequency shifts

to higher values. These results suggest the presence of electricalrelaxation in the material, which depends on temperature(Kumer and Manna, 2008). The variation of peak frequency,

fmax as function of temperature which obeys to Arrheniusrelation (3) is shown in Fig. 7b.

fmax ¼ f0 expð�Ef=kTÞ ð3ÞThe activation energy corresponding to electrical relaxation

has been calculated to be Ea(1) = 0.98 eV at high temperaturesand Ea(2) = 0.35 eV at low temperatures, which is almost

equal to those found from relation (2): Ea(1) = 0.94 eV andEa(2) = 0.39 eV.

3.5. Correlation between electrical and structural properties ofNa3Nb4As3O19

At 440 �C, we observe the change of the slope in the plot of ln(rT) against reciprocal temperature (Fig. 6a) which is due to

Table 4 Conductivity r (X�1 cm�1) and conduction activation ener

Compound Temperature range (K) Ea (e

Low ionic conductors

Na3Nb4As3O19 573–713 0.39

KFeAs2O7 558–668 0.47

Mild ionic conductors

NaCa1.5(NbO)2O2(AsO4)2 900–963 2.15

K3Cr3(AsO4)4 563–703 1.21

Ag0.62K0.38Nb4AsO13 603–883 0.807

Ag4Co7(AsO4)6 403–483 0.45

NaCa1.5(NbO)2O2(AsO4)2 703–900 1.14

Na0.5K0.65Mn3.43(AsO4)3 493–673 0.762

KMn6(As2O7)2(As3O10) 663–843 1.11

Good ionic conductors

Ag12.4Na1.6Mo18As4O71 448–693 0.763

TlFe0.22Al0.78As2O7 623–808 0.656

Li3Sc2(AsO4)3 400–600 0.910

Na3Nb4As3O19 713–893 0.94

Very good ionic conductors

Li3Fe2(AsO4)3 400–600 0.710

Na3Sc2(AsO4)3 400–600 0.460


transition phase or the existence of two mechanisms of ionicconductivity. To distinguish between these two possibilities,

Differential Scanning Calorimetry (DSC) analysis of Na3Nb4-As3O19 has been conducted over the temperature range 25–485 �C. A zoom of the thermal analysis results in the range

400–485 �C is shown in Fig. 9.At 440 �C, DSC thermogram does not present any phase

transition or other thermal phenomenon. This result con-

firms the existence of two mechanisms of ionic conductivitygoverned by the crystallographic structure.

In fact, according to the data of the structural study of Na3-Nb4As3O19, there are two kinds of tunnels where Na+ cations

are located. Their section dimensions are illustrated in Figs. 10and 11.

The first type of tunnels is large (Fig. 10) with maximum

cross equal to 13.014 A containing a bottleneck of smallwidth equal to 4.705 A which is inferior to 2(rO2- + rNa+) =2(1.38 + 1.12) = 5 A according to Shannon (1976).

However, the second type of tunnels (Fig. 11) has hexago-nal section. The dimensions of these tunnels vary from 6.354 to9.390 A. Both of them are longer than twice the sum of rayrO2- = 1.38 A and rNa+ = 1.02 A according to Shannon

(1976).

gy Ea (eV) of previous works.

V) r (X�1 cm�1) Reference

r733K = 2.68 � 10�6

This work

r668K = 0.28 � 10�6 Ouerfelli et al. (2007a,b)

r963K = 9.73 � 10�5 Ben Amor et al. (2008)

r703K = 4.61 � 10�5 Bouzemi Friaa et al. (2003)

r883K = 3.87 � 10�5 Cherif et al. (2011)

r483K = 3.3 � 10�5 Marzouki et al. (2014)

r900K = 1.13 � 10�5 Ben Amor et al. (2008)

r673K = 0.89 � 10�5 Frigui et al. (2011)

r843K = 0.65 � 10�5 Frigui et al. (2010)

r713K = 4.66 � 10�4 Hajji and Zid (2012)

r808K = 3.45 � 10�4 Ouerfelli et al. (2007a,b)

r600K = 1.40 � 10�3 Goodenoough et al. (1976)

r893K = 1.15 � 10�4

This work






Adding to this, the presence of Na+ cations with a partialoccupancy facilitates their mobility. We report in Table 3 theoccupancies of these cations.

These geometric factors are causing an ion mobility reach-ing 1.15 � 10�4 X�1 cm�1 at 893 K and 2.68 � 10�6 X�1 cm�1

at 733 K. These values, compared to those found in other com-

pounds, enable us to conclude that our compound can beplaced in the family of low ionic conductors at lowtemperatures and the family of good ionic conductors at high

temperatures (Table 4).

4. Conclusion

Crystals of Na3Nb4As3O19 were obtained by a solid-statereaction. Different characterization techniques have been used:infrared spectroscopy, powder X-ray diffraction and ionic

conductivity. The structure of this material has an open frame-work delimiting two kinds of tunnels parallel to [001] whereNa+ cations are located. Ionic conductivity study versustemperature is undertaken. It reveals that this material can

be classified as low ionic conductor at low temperatures andas good ionic conductor at high temperatures.

Acknowledgment

The authors gratefully acknowledge the financial support

of Ministry of Higher Education, Scientific Research andTechnology of Tunisia.

References

Anantha, P.S., Hariharan, K., 2005. Ac conductivity analysis and

dielectric relaxation behaviour of NaNO3–Al2O3 composite. Mater.

Sci. Eng. B 121, 12–19.

Ben Amor, R., Guesmi, A., Mazza, D., Zid, M.F., 2008.

Etudes physico-chimiques des arseniates de niobium Ag3Nb

(NbO)2O4(AsO4)2 et NaCa1.5(NbO)2O2(AsO4)2, simulation des

chemins de conduction ionique. J. de la Societe Chimique de

Tunisie 10, 83–92.

Bouzemi Friaa, B., Boughzala, H., Jouini, T., 2003. Tripotassium

trichromium (III) tetraarsenate K3Cr3(AsO4)4: synthesis, structural

study, IR spectroscopy characterization and ionic behavior. J. Solid

State Chem. 173, 273–279.

Altermatt, Brown, 1987. Celref version 3.0. Acta Cryst., Sect. A 34,

125–130.

Cherif, S.F., Ben Amor, F., Zid, M.F., Driss, A., Madani, A., 2011b.

Synthesis, structural study, IR spectroscopy characterization and

ionic behavior of Ag0.62K0.38Nb4AsO13. J. de la Societe Chimique

de Tunisie 13, 179–190.


Cherif, S.F., Hizaoui, K., Zid, M.F., Driss, A., 2012a. Non-cen-

trosymmetric Na3Nb4As3O19. Acta Cryst., Sect. E 68, i25–i26.

Cherif, S.F., Zid, M.F., Driss, A., 2011a. K0.12Na0.54Ag0.34Nb4O9

AsO4. Acta Cryst., Sect. E 67, i10–i11.

Cherif, S.F., Zid, M.F., Driss, A., 2012b. Synthesis, crystal structure

and properties of a new compound, K8Nb7As7O39. Jordan

J. Chem. 7, 401–412.

Daidouh, A., Pico, C., Veiga, M.L., 1999. Structure features and ionic

conductivity of the AM4(PO4)3 orthophosphates: (A = Na, K, Rb;

M= Ni, Mn). Solid State Ionics 124, 109–117.

Daidouh, A., Veiga, M.L., Pico, C., 1997. Structure characterization

and ionic conductivity of Ag2VP2O8. J. Solid State Chem. 130,

28–34.

Frigui, W., Ben Amor, F., Zid, M.F., Madani, A., Driss, A., 2011.

Synthesis and physic-chemical study of Na0.5K0.65Mn3.43(AsO4)3compound. Jordan J. Chem. 6, 295–305.

Frigui, W., Falah, C., Boughzala, H., Zid, M.F., Driss, A., 2010.

Synthese et etude physic-chimique du materiau KMn6(As2O7)2(As3O10). J. de la Societe Chimique de Tunisie 12, 179–188.

Goodenoough, J.B., Hong, H.Y.P., Kafals, J.A., 1976. Fast Na+ ion

transport in skeleton structures. Mater. Res. Bull. 11, 203–220.

Hajji, M., Zid, M.F., 2012. Synthesis, structure and ionic conductivity

of the molybdenum arsenate: Ag12.4Na1.6Mo18As4O71. Solid State

Sci. 14, 1349–1354.

Kumer, A., Manna, I., 2008. Ionic conductivity and electrical

relaxation of nanocrystalline scandia-stabilized c-zirconia using

complex impedance analysis. Physica B 403, 2298–2305.

Marzouki, R., Guesmi, A., Georges, S., Zid, M.F., Driss, A., 2014.

Structure, sintering and electrical properties of new ionic conductor

Ag4Co7(AsO4)6. J. Alloys Compd. 586, 74–79.

Masquelier, C., d’Yvoire, F., Collin, G.J., 1995. Crystal structure of

Na7Fe4(AsO4)6 and a-Na3Al2(AsO4)3, two sodium ion conductors

structurally related to II-Na3Fe2(AsO4)3. J. Solid State Chem. 118,

33–42.

Nakamoto, K., 1978. Infrared and Raman Spectra of Inorganic and

Coordination Compounds, third ed. Wiley-Inter-Science, New

York.

Ouerfelli, N., Guesmi, A., Mazza, D., Madani, A., Zid, M.F., Driss,

A., 2007b. Synthesis, crystal structure and mono-dimensional

thallium ion conduction of TlFe0.22Al0.78As2O7. J. Solid State

Chem. 180, 1224–1229.

Ouerfelli, N., Guesmi, A., Molinie, P., Mazza, D., Zid, M.F., Driss,

A., 2007a. The iron potassium diarsenate KFeAs2O7 structural,

electrical and magnetic behaviors. J. Solid State Chem. 180, 2942–

2949.

Shannon, R.D., 1976. Revised effective ionic radii and systematic

studies of interatomic distances in halides and chalcogenides. Acta

Cryst., Sect. A 32, 751–764.

ZView Version 3.1c Scribner Associates, Inc., Written by Derek

Johnson, 1990–1997.


http://refhub.elsevier.com/S1878-5352(15)00287-7/h0005




















































































































































Documents

Conductivity study by complex impedance spectroscopy … · Conductivity study by complex impedance ... cell parameters were reﬁned using Celref 3.0 program ... Conductivity study