La2CoTi0.7Mg0.3O6 (LCTM) material has been prepared at 1473 K for 24 h in air. X-ray powder diffraction study has revealed that it contains two orthorhombic perovskite phases (in a ratio ~1:4) with close unit cell parameters. Annealing of LCTM in reducing (Ar/H2, 8%) atmosphere at 1173 K for 12 h has resulted in the preparation of a single-phase material containing the GdFeO3-type perovskite phase with the unit cell parameters of a = 5.5631(3) Å, b = 5.5462(3) Å, c = 7.8522(5) Å. LCTM material exhibits a reversible transformation of a mixture of two perovskite phases with close cation content in air and a single perovskite phase in a reducing atmosphere. Both as-prepared and reduced LCTM samples have been studied by thermogravimetric analysis and dilatometry in air and Ar/H2 (8%). No chemical interaction between the as-prepared LCTM and standard electrolyte materials for SOFC like GDC and YSZ has been observed up to 1273 K. High-temperature electrical conductivity of the as-prepared LCTM at variable oxygen partial pressure (10−4-0.21 atm) showed weak dependence over pO2 with Ea = 0.48 ± 0.01 eV. AC impedance study of the symmetrical cells LCTM/GDC/LCTM has revealed ASR value at 1173 K of ~8.1 ± 0.1 Ω∙cm2 in air and 0.24 ± 0.05 Ω∙cm2 in a reducing atmosphere. These results allow to consider LCTM as a promising electrode material for a symmetrical SOFC.
- High-temperature electrical conductivity
- Symmetrical solid oxide fuel cell
- Thermal expansion