Magnetocaloric effect in the (Mn,Fe)2(P,Si) system: From bulk to nano

In the field of nanoscale magnetocaloric materials, novel concepts like micro-refrigerators, thermal switches, microfluidic pumps, energy harvesting devices and biomedical applications have been proposed. However, reports on (Mn,Fe)2(P,Si)-based which are one most promising bulk materials for solid-state magnetic refrigeration, rare. this study we synthesized nanoparticles, systematically investigated influence crystallite size microstructure giant effect. The results show that decreased saturation magnetization (Ms) is mainly attributed to increased concentration an atomically disordered shell, with a particle size, both hysteresis Tc reduced. addition, determined optimal temperature window annealing after synthesis 300–600 °C found gaseous nitriding can enhance Ms from 120 148 Am2kg?1 entropy change (?Sm) 0.8 1.2 Jkg?1K?1 in ??0H = 1 T. This improvement be synergetic effect nitration, effectively removes part defects inside particles. produced superparamagnetic particles probed by high-resolution transmission electron microscopy, Mössbauer spectra measurements. Our provide important insight into performance at nanoscale.