Magnetic properties and magnetic-entropy change of MnFeP0.5As0.5-xSix(x=0-0.3) compounds

The effects of Si substitution for As on the magnetic and magnetocaloric properties of MnFeP0.5As0.5-xSix compounds have been investigated. The Si-substituted compounds MnFeP0.5As0.5-xSix 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 MnFeP0.5As0.5-xSix compounds crystallize in the Fe2P-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. (C) 2006 American Institute of Physics.