Na/Li substitution effect on the structural, electrical and magnetic properties of LiCr(MoO4)2 and β-Li0.87Na0.13Cr(MoO4)2

JOURNAL OF ALLOYS AND COMPOUNDS

卷:854

Article

Sonni, Manel^1,2  Zid, Mohamed Faouzi¹  Hlil, El Kebir³  Zaidat, Kader⁴  Rossignol, Cecile²  Obbade, Said² 

[1] Fac Sci Tunisia, Lab Mat Crystallog & Appl Thermodynam, Tunis, Tunisia

[2] Univ Savoie Mont Blanc, Univ Grenoble Alpes, CNRS, Grenoble INP,LEPMI, F-38000 Grenoble, France

[3] Grenoble Alpes Univ, Neel Inst, MCBT UPR CNRS, F-38000 Grenoble, France

[4] Univ Grenoble Alpes, Grenoble INP, SIMAP UMR CNRS, F-38000 Grenoble, France

关键词: Bi-molybdate;    Crystal-structure;    X-ray diffraction;    Impedance spectroscopy;    Ions pathway simulation;    Magnetic properties;    Thermal expansion;   

DOI  :  10.1016/j.jallcom.2020.154740

来源: Elsevier

【 摘 要 】

The novel bi-molybdate beta-Li0.87Na0.13Cr(MoO4)(2) was prepared by solid state reaction route. Single crystal X-ray diffraction experiment revealed that the compound crystallizes in the triclinic system, in P -1 space group with a = 6.715 (2), b = 7.160 (3), c = 7.237 (1) angstrom, alpha = 91.16 degrees (3), beta = 110.59 degrees (2), gamma = 105.54 degrees (3). Its crystal structure is isotypic to LiCr(MoO4)(2) which has interesting magnetic and electrochemical properties [1-3]. Bond valence sum (BVS) and charge distribution (CHARDI) validation tools supported the structural model. The electrical properties were systematically studied by impedance spectroscopy. The ionic conductivity measurements are performed on pellets of 82% and 87% relative density for LiCr(MoO4)(2) and beta-Li0.87Na0.13Cr(MoO4)(2) respectively. AC impedance spectroscopy studies show that the highest overall conductivity is sigma(326 degrees C) = 7.86 x 10(-7) S cm(-1) Probable diffusion pathways of Li+ ions in the both structures were simulated using the bond valence sum BVS maps method. This analysis shows that the ionic transport in these materials is essentially due to simple hopping of Li+ ions parallel to (101) plane. For beta-Li0.87Na0.13Cr(MoO4)(2) compound, the in-situ High Temperature X-Ray Diffraction (HTXRD), in the temperature range from 25 to 650 degrees C, were also performed and Unit-cell thermal expansion has been discussed. The magnetic study show that these compounds present an antiferromagnetic order below the temperatures T-N = 16 and 30 K for LiCr(MoO4)(2) and beta-Li0.87Na0.13Cr(MoO4)(2) respectively. (C) 2020 Elsevier B.V. All rights reserved.

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