The effect of Zr-substitution in La1‐xSrxCo0.2M0.6Zr0.2O3‐δ (M = Fe, Mn) on the crystal structure, thermal expansion and electronic transport properties

The effect of Zr-substitution on the evolution of crystal structure, thermal expansion and the electronic transport properties is reported for La1‐xSrxCo0.2Fe0.6Zr0.2O3‐δ (0.1 ≤ x ≤ 1.0) and La1‐xSrxCo0.2Mn0.6Zr0.2O3-δ (x = 0.1, 0.2, 0.25, 0.3). La1‐xSrxCo0.2Fe0.6Zr0.2O3‐δ was found to be single-phase for the compositions investigated. The electrical conductivity of La1‐xSrxCo0.2Fe0.6Zr0.2O3‐δ demonstrated a maximum for x = 0.5, while the area specific resistance was shown to decrease significantly with increasing Sr-content due to an increased concentration of oxygen vacancies. No signs of oxygen vacancy ordering were observed. The area specific resistance of La0.3Sr0.7Co0.2Fe0.6Zr0.2O3‐δ at 600 °C is close to an order of magnitude lower than reported values for La0.4Sr0.6Co0.2Fe0.8O3‐δ. The series La1‐xSrxCo0.2Mn0.6Zr0.2O3‐δ was found as multiphase materials. The stability of both series is discussed with respect to the red-ox properties of the transition metals.