Tuning transition temperature of magnetocaloric Mn1.8Fe0.2(P0.59Si0.41)x alloys for cryogenic magnetic refrigeration

Giant magnetocaloric effect in Mn1.8Fe0.2(P0.59Si0.41)x ( x = 1.00, 1.01, 1.02, 1.03, 1.04) alloys is assessed for cryogenic temperature applications. We found that the Curie temperature can be tuned from. 300 K to 99 K by increase of Mn/Fe and P/Si ratios. We systematically optimized metal/non-metal ratio and homogenization condition to maximize the volume fraction of the Fe2P-type phase. A giant isothermal magnetic entropy changes of 10.6 and 14.0 J/kgK under a magnetic field of 2.0 and 5.0 T is obtained at 117.0 K for Mn1.8Fe0.2(P0.59Si0.41)1.03 alloy. This work demonstrates low-cost Mn-Fe-P-Si alloys with giant MCE are competitive candidates compare to the rare-earth-containing magnetocaloric compounds for cryogenic applications.