Study on effect of substitution on conductivity and phase transition in oxide ion conductors

Abstract

Fuel cells represent a promising and viable alternate for large scale generation of electricity. Solid oxide fuel cell (SOFC) is the most advance field in the science of fuel cell due to their high efficiency than other type of fuel cells. The obstacle in the commercialization of SOFCs is their high operating temperature. Solid electrolyte is the most important part of SOFC and many efforts have been carried out to develop a suitable electrolyte, with higher ionic conductivity in intermediate temperature range (400-700°C). Several electrolyte materials have been studied and it was found that the BIMEVOX (doped bismuth vanadates) family of oxide-ion conductors show higher conductivity at intermediate temperatures when doped with various aliovalent cations. So this family of oxide-ion conductors can be used in many technological applications like oxygen sensors, air separators and solid oxide fuel cells (SOFCs) etc. The objective of the present work entitled Study on effect of substitution on conductivity and phase transition in oxide ion conductors is to demonstrate the superiority of the bismuth vanadate based solid electrolytes as compared to commonly used electrolyte materials like Yttria stabilized zirconia, doped ceria and lanthanum gallates etc. In this study we prepared four new electrolytes namely BICAVOX, BIBAVOX, BISNVOX and BIMNVOX solid solutions by doping on thevanadium site by conventional solid state reactions. The structural properties, phase transitions and oxide-ion conductivity were calculated by using different techniques like FT-IR spectroscopy, Differential Thermal Analysis, X-ray Diffraction Analysis and AC Impedance Spectroscopy.