Phase Stability of The Mixed-Conducting Sr-Fe-Co-O System

Mixed-conducting ceramic oxides have potential uses in high-temperature electrochemical applications such as solid oxide fuel cells, batteries, sensors, and oxygen-permeable membranes. The Sr-Fe-Co-O system combines high electronic/ionic conductivity with appreciable oxygen permeability at elevated temperatures. Dense ceramic membranes made of this material can be used to separate high-purity oxygen from air without the need for external electrical circuitry, or to partially oxidize methane to produce syngas. Samples of Sr 2 Fe 3-x Co x O y (with x = 0,0.6,1.0, and 1.4) were prepared by solid-state reaction method in atmospheres with various oxygen partial pressures (pO 2 ) and were characterized by X-ray diffraction, scanning electron microscopy, and electrical conductivity testing. Phase components of the sample are dependent on cobalt concentration and pO 2 . Electrical conductivity increases with increasing temperature and cobalt content in the material.