Thermal stability, oxygen non-stoichiometry, electrical conductivity and diffusion characteristics of PrNi0.4Fe0.6O3−δ, a potential cathode material for IT-SOFCs

The potential use of a double B mixed-perovskite as a promising cathode material in intermediate temperature solid oxide fuel cells (IT-SOFCs) has been anticipated as a result of this work. A thorough investigation of some important parameters like thermal stability, thermal expansion, oxygen non-stoichiometry, electrical conductivity and diffusion characteristics of the PrNi0.6Fe0.4O3−δ ceramic sample have been investigated as functions of temperature (20–1000 °C) and oxygen partial pressure (0.6–21,000 Pa). According to the measurements, the composition was phase stable at pO2 > 1 Pa up to 1000 °C and shows p-type semiconductivity with a low conductivity versus pO2 dependence.The perovskite has been found to have comparable thermal expansion coefficients with those of commonly used solid electrolytes like CeO2 and ZrO2 based oxides. In case of the chemical diffusion experiments higher oxygen diffusion mobility observed during reduction processes in comparison with those during oxidation have been explained by the already known formation of neutral defect clusters.

A typical exponential decay curve of the relative conductivity with time during stepwise change in temperature at constant oxygen concentration in gas phase (experimental curve and a perfect model fit).Figure optionsDownload as PowerPoint slide