High-temperature phase equilibria in the oxide systems SrFe1−xGaxO2.5–SrFe1−xGaxO3 (image, 0.1, 0.2)

X-ray powder diffraction, Raman scattering, equilibrium oxygen content and conductivity data are combined to construct high-temperature phase diagrams (T vs. δ) for the oxide systems SrFe1−xGaxO2.5–SrFe1−xGaxO3, where image, 0.1, and 0.2. Depending on oxygen content and gallium doping, three different structural types are shown to exist at high temperatures including cubic perovskite-, cubic brownmillerite-, and orthorhombic brownmillerite-type structures. Substitution of gallium for iron is shown to extend the oxygen content and temperature limits where the cubic brownmillerite-type phase is stable.