Structural stability of SrCo1-xFexO3-δ solid solutions

SrCo1-xFexO3-delta solid solutions with 0.3 <= x <= 0.9 are shown to have the cubic perovskite structure. The unit-cell parameter and volume of the solid solutions are nonmonotonic functions of Fe content, with a minimum at x = 0.4. Dilatometric data are used to determine the thermal expansion coefficients of the solid solutions. At low oxygen partial pressures (po(2) <= 40 Pa), the high-temperature, disordered perovskite phase exists between 850 and 1000 degrees C, which is the optimal temperature range for the effective use of SrCo1-xFexO3-delta ceramics as oxygen membranes in oxygen partial pressure gradients of 10(4)-10(5)/10-100 Pa.