Solution combustion synthesis and electrical conductivity studies of nanocrystalline Li2NiZrO4 material

Li2NiZrO4 nanocrystalline material is synthesized by solution combustion technique. It is a new class of lithium rich transition metal oxides, namely, Li2MXO4 (M = Ni, Mg, Mn, Fe, Co, Cu and Zn; X= Zr, Hf), used as electrode for the lithium ion secondary batteries. Solution combustion synthesis is a novel technique for preparation of nanocrystalline materials. In this study citric acid is used as a fuel; which forms citrate complexes with metal ions. pH of the homogenous solution is maintained above 8 for avoiding precipitate formation thus for maintaining stoichiometry of compound. Gel obtained after evaporation of homogenous solution of nitrates. This material was treated thermally at 900 deg C for 6h in air. The heat treating procedure was estimated utilizing the thermogravimetric (TG) analysis. The sintered powder was consisting of single phase of Li2NiZrO4 which was confirmed by X-Ray Diffraction (XRD) and the average crystallite size is calculated from the Scherrer formula is 53 nm. Electrical properties of nanocrystalline size material are studied over wide range of temperature and frequency. The electrochemical studies were done by Broad Dielectric Spectroscopy (BDS). Dielectric Spectroscopy tool is used to obtain equivalent circuit, thus separating grain-interior and grain-boundary elements. The activation energies for dc conduction and hopping frequency are calculated from the Arrhenius plot and results will be discussed later. (author)