Cu Doping Effect on Electrical Resistivity and Seebeck Coefficient of Perovskite-Type LaFeO₃ Ceramics

Perovskite-type LaFe_1-xCu_xO₃ (x=0.10, 0.14, 0.18) solid solution is prepared with the conventional solid-state reaction technique. The electrical resistivity and the Seebeck coefficient are measured in the temperature range 473-1073K to elucidate the Cu doping effect on the thermoelectric properties of the LaFeO₃. The electrical resisitivity of LaFe_1-xCu_xO₃ shows semiconducting behavior. The temperature dependence of the electrical resistivity indicates that the adiabatic small-polaron hopping mechanism is dominant for their electric transportations. The activation energy decreases with the increasing Cu content as well as the increasing temperature. The Seebeck coefficient changes from a negative value to a positive value around 510K, and increases with rising temperature up to 710K, then becomes saturated around 200μV/K. The Seebeck coefficient decreases with the substitution of Cu atoms in the temperature range of 573-1073K, while the electrical resistivity decreases with the substitution of Cu atoms in the whole measured temperature. Overall the power factor increases with rising temperature, and the highest value of power factor is 54μW/K²m for x=0.10 of Cu doping.