Carbon doping in the Mn1.15Fe0.80P0.50Si0.50 materials: Structure, phase transition and magnetocaloric properties

Abstract

The Mn1.15Fe0.80P0.50-xSi0.50Cx materials with x = 0, 0.01, 0.03, 0.05 were prepared by arc-melting and subsequent sintering. The structure and magnetic characteristics for these compounds were examined by X-ray diffraction, vibrating sample magnetometer, differential scanning calorimetry and Raman spectrometry. The results indicate that all samples mainly form the Fe2P-type phase. The enlarged unit-cell volume of Fe2P phase and a few carbon content in impurity phases reveal that the carbon atoms should enter the Fe2P structure. With increasing carbon contents, the Curie temperature can be increased from 289 K to 347 K and the thermal hysteresis is significantly reduced by almost 50%, from 31.5 K to 15.8 K. Under a field of 1 T, the maximum magnetic entropy change and the peak value of adiabatic temperature change increases by 80% and 68% by adding carbon, respectively. This increased performance makes (Mn,Fe)2(P,Si,C) materials a great candidate for room-temperature magnetic refrigerant applications.