Preparation and Characterization of LaCu_1-xM_xO₃(M=Fe, Ni)

Abstract

The perovskite solid solutions, LaFe_1-xCu_xO₃ and LaFe_1-xCu_xO_3-z were prepared under high oxygen pressure and the phase relations and electrical properties were investigated. In the system of LaFe_1-xCu_xO₃, orthorhombic type LaFeO₃ changed to rhombohedral type LaCuO₃ at x=0.6. The electricresistivity of the rhombohedral phase was lower 2 or 3 order in the magnitude than that of the orthorhombic one. In LaFe_1-xCu_xO₃, the oxygen nonstoichiometric samples showed the rhombohedral structure in all x range with metallic conductivity and Pauli paramagnetism. The Seebeck coefficient measurement showed the dominant carriers for x <0.8 are electron, and hole for x>0.8. The perovskite LaFe_1-xCu_xO_3-z is able to have a large amount of oxygen vacancy, where a cubic perovskite like phase having the disordered arrangement is realized.