Structure, Linear Thermal Expansion Coefficient, and Electrical Conductivity of Y0.9Ca0.1Cr1 – уCoуO3 (у = 0–0.9) Perovskites

Resumo

The structure, thermal expansion coefficient, and electrical conductivity of Y_0.9Ca_0.1Cr_1 – уCo_уO₃ (у = 0–0.9) compounds with the perovskite structure have been investigated in air in the temperature range of 100–1000°С. The linear thermal expansion coefficient of Y_1 – хCa_хCr_1 – уCo_уO₃ lies in the range of (8.77–16.1) × 10^–6 K^–1. The maximum electrical conductivity is attained for the Y_0.9Ca_0.1Cr_0.6Co_0.4O₃ composition. It is shown that the electrical conductivity at low (25–270°С) temperatures and weak substitution of cobalt for chromium is mainly due to the hopping of one electron hole from Cr⁴⁺ to Cr³⁺. At high (565–1000°С) temperatures and cobalt contents, this conductivity mechanism is supplemented with the conductivity caused by the hopping of an electron hole from Cо³⁺ to Cо²⁺.