Magnetic properties and magnetocaloric effects of Gd–Mn–Si ribbons in amorphous and crystalline states

Abstract

The amorphous Gd65Mn35−xSix (x=5 and 10) ribbons were prepared by melt-spinning. The nanocrystalline Gd65Mn25Si10 alloy consisting of a main hexagonal α-Gd(Mn) phase and a small amount minor phases was also obtained by annealing the amorphous ribbons. The magnetic properties and magnetocaloric effects of these alloys were investigated. The maximum magnetic entropy changes for the amorphous alloys with x=5 and 10 are 4.6 and 4.7Jkg−1K−1, respectively, for a magnetic field change from 0 to 5T. All these amorphous alloys have a broad temperature range of the magnetic-entropy peak, resulting in large refrigeration capacities, 625 and 660J/kg for x=5 and 10, respectively. For the crystallized Gd65Mn25Si10 alloy, a relative large magnetic entropy change (∼4.6J/kg−1K−1) and refrigeration capacity (249J/kg) under a field change of 0–5T is obtained. The large refrigeration capacity and the absence of thermal/magnetic hysteresis losses indicate that the amorphous Gd65Mn35−xSix alloys are good candidates for working in active magnetic refrigeration at the temperature range of 125–275K.