Oxygen deficiency and phase transitions in SrCo1– x – y Fe x Cr y O3– δ (x=0.10–0.40, y=0–0.05)

Abstract

Oxygen-deficient phases based on perovskite-like strontium cobaltites-ferrites are promising mixed conductors for high-temperature electrochemical applications. The p(O2)-T-δ diagrams for the oxide systems SrCo1–x–yFexCryO3–δ (x=0.10–0.40; y=0–0.05) were studied at 500–1000 °C in the oxygen pressure range from 10–5 to 0.21 atm using the coulometric titration technique and thermogravimetric analysis. Stability limits of the cubic perovskite phases having a high oxygen ionic conductivity were evaluated as functions of temperature, oxygen partial pressure and oxygen nonstoichiometry. It was found that doping with chromium and increasing the iron content in SrCo(Fe,Cr)O3–δ both lead to a considerable enlargement of the cubic perovskite phase existence domain towards lower temperatures and reduced oxygen pressures.