Electrical properties and alkali-pathways simulation of new mixed conductor Na4Li0.62Co5.67Al0.71(AsO4)6

Abstract

Polycrystalline sodium lithium-cobalt-aluminum arsenate, Na4Li0.62Co5.67Al0.71(AsO4)6, was synthesized by solid state reaction route and characterized by infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The title material is a member of β-Xenophyllite family which show 3D anionic framework with interconnecting tunnels where alkali-ion are located. Dense ceramic with relative density of 97% is obtained after planetary grinding of the synthesized powder followed by optimal sintering at 1113 K. The effect of grinding on microstructure of sample is controlled by Scanning Electron Microscope (SEM). The electrical study using impedance spectroscopy, in the 443-773 K temperature interval, show interesting electrical performance of the dense ceramic: σ 433K = 1.41 10-5 Scm-1 and the activation energy Ea = 0.449 eV. The alkali migration pathways in the anionic framework were simulated using Bond Valence Site Energy (BVSE) model to correlate structure with electrical properties of the studied material. The calculation results were compared to other β-Xenophyllite materials.