Thermal Expansion and Conductivity of Sm0.9Ca1.1Fe1 – yCoyO4 – δ Solid Solutions

Abstract

Complex oxides Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are synthesized in air at 1100°С using the glycerol-nitrate technique. The temperature dependences of the total electrical conductivity, Seebeck coefficient, and thermal expansion of the compositions Sm0.9Ca1.1Fe1 − yCoyO4 − δ (y = 0, 0.7) are studied in the 25–1100°C temperature range and at $${{P}_{{{{{\text{O}}}_{2}}}}} = 0.21$$ atm. The average TEC values are calculated over linear sections of the ΔL/L = f(T) dependences. It is shown that the considered samples possess semiconductor-type conductivity. An increase in the concentration of cobalt raises the total electrical conductivity of Sm0.9Ca1.1Fe1 − yCoyO4 − δ. The activation energy of conductivity is calculated from the dependences of the total electrical conductivity of oxides in Arrhenius coordinates. It is found that the temperature dependence of the Seebeck coefficient for Sm0.9Ca1.1FeO4 − δ has positive values in the range of 25–1100°C, testifying to the predominance of hole conductivity.