Effect of Carbon Doping on the Structure and Magnetocaloric Properties of Mn1.15Fe0.80P0.50Si0.50 Compounds

The Mn1.15Fe0.80P0.50Si0.50Cx compounds with x = 0, 0.01, 0.03, and 0.05 were prepared by twice solid-phase sintering and we investigated the changes of the structure and magnetocaloric properties by C doping. All samples are found to show Fe2P-type structure with minor impurity phase and some carbon atoms enter into Fe2P-type main phase and occupy the interstitial site. Carbon addition leads to an increase of the Curie temperature from 289 to 321 K and the thermal hysteresis has a reduction about 31.5%. All samples show distinct first-order magnetic transition. The peak value of magnetic entropy change and adiabatic temperature change is increased by 26% and 11% with addition of carbon under a low field of 0–2 T, respectively. The large magnetocaloric effect might be resulted from the latent heat of phase transition induced by temperature derived from calorimetric measurements. The results indicate that (Mn,Fe)2PSiC compound with large magnetocaloric effect is a good candidate for room temperature magnetic refrigeration.