Synthesis and characterization of orthovanadates compounds Li(1−x) NaxCdVO4 (x = 0, 0.25)

Orthovanadates LiCdVO4 and Li0.75Na0.25CdVO4 compounds have been obtained by the conventional solid-state reaction and characterized by X-ray powder diffraction. The crystal structure determination, of both samples, indicates that they are isostructural. The following crystal data were obtained: orthorhombic, Cmcm, Z = 4, (a = 5.924(1) Å, b = 8.980 (2) Å, c = 6.504(1) Å and V = 346.064(1) Å3) for LiCdVO4 and (a = 5.899(1) Å, b = 9.039(2) Å, c = 6.629(1) Å and V = 352.878(1) Å3) for Li0.75Na0.25CdVO4. Impedance spectroscopy measurements of LiCdVO4 and Li0.75Na0.25CdVO4 were conducted in the frequency and temperature range (209 Hz-1 MHz) and (582 K-709 K), respectively. Besides, the impedance spectra are well fitted to an equivalent circuit consisting of series combination of grains and grains boundaries. It was found that the non-overlapping small polaron tunneling (NSPT) model is suitable to describe the conduction mechanism in these two compounds.