High Temperature Thermoelectric Properties of Ca_1-xDy_xMnO_2.98 (0≤x≤0.2)

Abstract

High temperature thermoelectric properties of Ca_1-xDy_xMnO_2.98 (x=0, 0.05, 0.10, 0.15, 0.20) have been measured in the temperature range from 300 to 1273K. Ca_1-xDy_xMnO_2.98 (x=0.10, 0.15, 0.20) exhibited the metal-insulator transition in the relation between electrical resistivity and temperature, and the transition temperature increased with increasing x. Electrical resistivity in the metallic region decreased with increasing x content, reflecting the increase of Mn³⁺ ions, and the absolute value of Seebeck coefficient (α) also decreased. Thermal conductivity (λ) did not considerably change with increasing x content. Among substituted CaMnO₃, the highest figure of merit of Z=1.05×10^-4K^-1 was obtained for x=0.05 and 0.10 at 773K, while a Z=1.63×10^-4K^-1 was obtained for x=0.20 at 1273K.