Thermal and chemical expansion properties of La0.2Sr0.8Fe0.55Ti0.45O3−x

The thermal and chemical expansion coefficients for La0.2Sr0.8Fe0.55Ti0.45O3−x were measured at 800 ≤ T ≤ 1200 °C and at ∼1 × 10− 15 ≤ pO2 ≤ 0.21 atm. Measurements of the total expansion coefficient in air, on heating and cooling between room temperature and 1200 °C, are reproducible. The average thermal expansion coefficient of La0.2Sr0.8Fe0.55Ti0.45O3−x is 9.3 ± 1.1 × 10− 6 K− 1 over the whole temperature range, similar to the values reported for other titanium substituted perovskites and yttria-stabilized zirconia. The chemical expansion coefficients measured at 800 °C vary linearly with the degree of oxygen non-stoichiometry. At higher temperatures, the chemical expansion shows a pronounced non-linear dependence on stoichiometry. At oxygen partial pressures below ∼10− 6 atm, the expansion shows evidence of the slow kinetic behavior previously observed in stoichiometry and conductivity measurements.