Gd0.05 Bi0.15 M0.05 Ce0.75 O2 solid solutions for IT-SOFC electrolyte application

Abstract

A large part of the world’s energy demand is met by fossil fuels. Fossil fuels are limited sources and they cause environmental pollution. Among the alternative energy sources, solid oxide fuel cells (SOFCs) attract attention. Ceria doped with heterovalent cations, such as rare earth and alkaline earth ions, have been extensively studied as the most promising electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFC). As well known, phase purity and relative density are important factors for obtaining high performance doped ceria electrolytes. The nanocrystalline powders of Gd-Bi-M-Ce-O (M = Cu, Zr, Ni, Co, Mn) solid solutions with the size of about 10 nm were used as precursors to ceramics formation, sintered at 750°C in air, for the application of these materials as a perspective electrolyte for IT-SOFC. Crystal structures and morphologies of these products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The electrical conductivity was measured by AC impedance spectroscopy in the temperature range of 450 – 750°C in air. It was showed that Gd0.05 Bi0.15 Mn0.05 Ce0.75 O2 ceramics is the perspective electrolyte and has the conductivity of 8 ·10−3 S/cm. Ceria doped with these oxides have a high ionic conductivity by the formation of oxygen ion vacancy due to the substitution of Ce4+ with other cations.