Novel complex oxides Sr2Ga1+x In1-x O 5, x=0.0-0.2 with brownmillerite-type structure were prepared in air at T=1,273 K, 24 h. Study of the crystal structure of Sr2Ga 1.1In0.9O5 refined using X-ray powder diffraction data (S.G. Icmm, a=5.9694(1) Å, b=15.2091(3) Å, c=5.7122(1) Å, χ 2=2.48, R F 2 =0.0504, R p=0.0458) revealed ordering of Ga3+ and In3+ cations over tetrahedral and octahedral positions, respectively. A partial replacement of Sr2+ by La3+ according to formula Sr1-y La y Ga0.5In 0.5O2.5+y/2, leads to the formation of a cubic perovskite (a=4.0291(5) Å) for y=0.3. No ordering of oxygen vacancies or cations was observed in Sr0.7La0.3Ga0.5In 0.5O2.65 as revealed by electron diffraction study. The trace diffusion coefficient (D T) of oxygen for cubic perovskite Sr0.7La0.3Ga0.5In0.5O 2.65 is in the range 2.0×10-9-6.3×10 -8 cm2/s with activation energy 1.4(1)eV as determined by isotopic exchange depth profile technique using secondary ion mass spectrometry at 973-1,223 K. These values are close to those reported for Ca-doped ZrO 2. High-temperature electrical conductivity of Sr 0.7La0.3Ga0.5In0.5O2.65 studied by AC impedance was found to be nearly independent on oxygen partial pressure. Calculated values of activation energy at T<1,073 K for hole and oxide-ion conductivities are 0.96 and 1.10 eV, respectively.
- Crystal structure
- High-temperature conductivity
- Oxygen diffusion
- Thermal expansion