Magnetic properties and magnetic-entropy change of MnFeP_(0.5)As_(0.5-x)Si_x(x= 0-0.3) compounds

摘要

The effects of Si substitution for As on the magnetic and magnetocaloric properties of MnFeP_(0.5)As_(0.5-x)Si_x compounds have been investigated. The Si-substituted compounds MnFeP_(0.5)As_(0.5-x)Si_x with x=0, 0.1, 0.2, and 0.3 have been prepared by high-energy ball milling and solid-state reaction. X-ray diffraction shows that all the MnFeP_(0.5)As_(0.5-x)Si_x compounds crystallize in the Fe_2P-type structure. Magnetic measurements show that the compounds are ferromagnetic with a nonlinear dependence of T_C on Si content. All compounds exhibit a field-induced first-order magnetic phase transition. The magnetic-entropy change is derived from the magnetization data by using the Maxwell relations. The maximum magnetic-entropy change observed in this system reaches about 32 J/kg K for a field change from 0 to 2 T for x=0.2, at temperature around 294 K.