Nickel effects on the structure, electrical and magnetic properties of La 0.7Ca 0.3Mn 1−xNi xO 3 ( x=0–0.05) manganite oxide

Abstract

We have investigated the structure, the magnetic and the electrical properties of Ni-doped La 0.7Ca 0.3Mn 1− x Ni x O 3 CMR system. From M–T curve, we determined the Curie temperature, where the magnetization value decreases abruptly. Curie temperatures of 250 K for La 0.7Ca 0.3MnO 3, 290 K for La 0.7Ca 0.3Mn 0.99Ni 0.01O 3, 280 K for La 0.7Ca 0.3Mn 0.97Ni 0.03O 3 and 260 K for La 0.7Ca 0.3Mn 0.95Ni 0.05O 3 were obtained. The amount of nickel increased, the Curie temperature decreased. It is considered that the decrement of magnetic order by decreasing of Mn 3+ and lattice distortion. In case of unsubstituted pellet, maximum magneto resistance (MR) ratio and metal semiconductor transition temperature appeared at 200 K. MR ratio tended to increase with temperature up to Curie temperature and showed the maximum values around Curie temperature. In addition, La 0.7Ca 0.3Mn 0.99Ni 0.01O 3 showed the highest MR ratio because it showed the highest Curie temperature. MR ratios of two pellets were 33% at 180 K for La 0.7Ca 0.3MnO 3 and 45% at 260 K for La 0.7Ca 0.3Mn 0.99Ni 0.01O 3.