Preparation and characterization of LiFe1/2Ni1/2VO4

A layered ceramic oxide, LiFe1/2Ni1/2VO4 has been prepared using solid-state reaction technique. The preparation conditions have been optimized using thermogravimmetric analysis (TGA) studies. The formation of the material sample under the reported condition has been confirmed by X-ray diffraction (XRD) analysis. XRD analysis indicates the crystal structure to be orthorhombic with lattice parameter: a = 3.5637 Å, b = 17.7486 Å, c = 12.2884 Å. The phase morphology and surface properties studied using scanning electron microscopy (SEM), suggest a polycrystalline texture with reasonable number of the voids. Complex impedance analysis of the sample has indicated: (i) conduction due to bulk contribution at T ≤ 200 °C, (ii) the presence of grain boundary effects at T ≥ 200 °C, (iii) negative temperature coefficient of resistance (NTCR) behaviour and (iv) evidence of temperature dependent electrical relaxation phenomena in the sample. The DC conductivity (σDC) shows typical Arrhenius behaviour when observed as a function of the temperature. The activation energy value has been estimated to be 0.42 eV. σDC, as evaluated from complex impedance spectrum, shows a jump of nearly ∼4 orders of magnitude in the value at higher temperature when compared to that of the room temperature value. AC conductivity spectrum obeys Jonscher's universal power law. The results of σAC as a function of frequency are also discussed.