Crystal Structure and Physicochemical Properties of Solid Solutions Ba0.5Sm0.5Fe1–yMnyO3–δ

Based on the results of XRD analysis of samples with the general formula Ba0.5Sm0.5Fe1–yMnyO3–δ, obtained using glycerol-nitrate technique with subsequent annealing at 1300°C in air, it was established that the homogeneity range of solid solutions with a cubic structure (space group Pm3̄m ) is in the interval 0.15 ≤ y ≤ 0.45. It is shown that the unit cell parameters of Ba0.5Sm0.5Fe1–yMnyO3–δ decrease with increasing manganese content. The oxygen deficiency (δ) in air at room temperature at a low manganese content (y = 0.15), determined by the iodometric titration method, does not exceed 0.1, and the oxygen content in oxides with y = 0.25 and 0.45 is close to stoichiometric. The linear thermal expansion coefficients (LTEC) of Ba0.5Sm0.5Fe1–yMnyO3–δ, obtained from dilatometric measurements, are in the range of (12.7–14.2) × 10–6 K–1 and are comparable with the LTEC of widely used electrolytes based on cerium oxide and zirconium oxide. It is shown that the relative thermal expansion of Ba0.5Sm0.5Fe1–yMnyO3–δ decreases with increasing manganese content. The temperature dependences of the total electrical conductivity of Ba0.5Sm0.5Fe1–yMnyO3–δ (y = 0.15, 0.35) have a maximum. The increase in electrical conductivity in the low-temperature region is explained by the increase in the mobility of charge carriers. The decrease in electrical conductivity in the high-temperature region is due to a decrease in the concentration of charge carriers (holes), which is associated with an increase in oxygen deficiency.