Magneto-caloric properties of La_(0.7)Ca_(0.3)(Ni_(1-x)Mn_x)O_3 compounds

摘要

The magneto-caloric effect and the magnetization behavior have been analyzed in the La_(0. 7)-Ca_(0. 3)(Ni_(1-x)Mn_x)O_3 (x = 0. 85, 0. 88, 0. 91, 0. 94, 0. 97, 1. 00) compound. Samples were prepared by using a standard solid-state reaction in a stream of 5% H_2/Ar gas. X-ray diffraction patterns revealed that all the samples had a single phase with an orthorhombic structure. The Curie temperature increased from 175 K to 269 K with increasing Mn concentration. The values of magnetic entropy change, ΔS_M are also increased from 1. 20 to 5. 64 J/kg K with increasing of Mn content. The enhancement of the magnetic entropy change is believed to be due to the occurrence of the strong magnetic ordering between Mn-Mn atoms. The interesting features of this compound make it a competitive candidate as a working material in magnetic refrigeration applications.