Effects of chemical stability of heterogeneous oxides on transport properties of La0.67Ca0.33MnO3

Abstract

Two kinds of composites of La 0.67 Ca 0.33 MnO 3 /ZrO 2 and La 0.67 Ca 0.33 MnO 3 /YSZ have been investigated, in which the heterogeneous oxide YSZ represents yttria-stabilized zirconia (8 mol% Y 2 O 3 + 92 mol% ZrO 2 ). Their transport properties are measured in a temperature range of 10–300 K and a magnetic field range of 0–3 T. With increase in ZrO 2 doping level for the range of 0–2%, the metal–insulator transition temperature, T P , decreases, but T P increases with the doping level increase further for higher than 2%. Meanwhile, in the composite of La 0.67 Ca 0.33 MnO 3 /ZrO 2 , besides the intrinsic metal–insulator (ferromagnetic–paramagnetic) transition, a new kink and a widen transition temperature region are observed both in the temperature dependence of resistivity and magnetization curves. Compared to pure La 0.67 Ca 0.33 MnO 3 and the composite of La 0.67 Ca 0.33 MnO 3 /YSZ, we assume that the different effects between ZrO 2 and YSZ on transport behavior of La 0.67 Ca 0.33 MnO 3 result mainly from their different chemical stability.