Effect of Co3+ substitution on the structure and magnetic properties of La0.6Ca0.4MnO3

Abstract

The effect of cobalt doping on the structure and magnetic properties of polycrystalline La0.6Ca0.4Mn1−x Co x O3 (0 ≤ x≤0.3) has been studied. X-ray powder diffraction and magnetization measurements have been performed. A high-crystallized La0.6Ca0.4Mn1−x Co x O3 with an orthorhombic structure is obtained when the precursor is calcined at 900 °C in air for 3 h. Different amounts of Co3+ ion doping do not lead to the formation of another phase except diffraction peaks shifts slightly. With increase in Co3+ doping from x = 0, 0.1, 0.2, to 0.3, lattice parameters (b value) increase at first, then decrease. Magnetic characterization indicates that specific magnetization of La0.6Ca0.4Mn1−x Co x O3 decreases with the increase of Co3+ additional amount; substitution of Mn by Co3+ ion can markedly increase the coercive field of La0.6Ca0.4Mn1−x Co x O3, attributed that Co3+ doping can decrease Mn3+/Mn4+ ratio in La0.6Ca0.4Mn1−x Co x O3. La0.6Ca0.4Mn0.7Co0.3O3 at 100 K had the highest coercive field value, 1889.7 Oe. The coercive field of La0.6Ca0.4Mn1−x Co x O3 is between 35.1 and 114.7 Oe, even at 200 K, indicating that La0.6Ca0.4MnO3 and doped Co3+ La0.6Ca0.4Mn1−x Co x O3 continue being ferromagnetic at 200 K.