Here, we report particle size dependent hysteresis loss in La0.7Ce0.3Fe11.6Si1.4C0.2. Hysteresis loss was getting smaller with reducing the particle size. The reduced ratio can be as high as ∼61% as the sample is ground from bulk into small particles (20-50 μm). Such reduction can be ascribed to the notably increased surface area of sample and the partially removed internal strain and grain boundaries, other than nucleation factors and electronic band structure. Meanwhile, entropy change |ΔS| slightly decreases, but the effective refrigeration capacity shows an increase due to the notable reduction of hysteresis loss. Our investigations also reveal particle size limitation. When the size is below 10 μm (average ∼ 4 μm), the sample may lose its stability and the |ΔS| notably reduces.

Here, we report the co-substitution of Fe and Co for Ni atoms on metamagnetic behavior, martensitic transformation, and transport and magnetocaloric properties in Ni 45 (Co 1Àx Fe x) 5 Mn 36.6 In 13.4 (x ¼ 0$0.05) alloys. It is found that the introduction of Fe atoms stabilizes martensitic phase and shifts martensitic temperature (T M) to higher temperature. Meanwhile, the Curie temperature T C of parent phase notably decreases. Upon Fe doping, the low magnetization of martensitic phase keeps nearly unchanged while the magnetization of parent phase slightly decreases. As a result, the Fe-doped samples maintain strong metamagnetic behavior and show great MR and MCE in an extended temperature range around room temperature. The hysteresis loss is reduced upon Fe-doping, which leads to an enhancement of effective RC by 15%. V

Here, we choose La-Ce-Pr-Nd industrial mischmetal with low purity as raw material to prepare La(Fe,Si)13-based magnetocaloric material and its hydride. It is demonstrated that the introduced impurities in the starting materials do not impair the formation of NaZn13-type structure. The multi-replacement of La by magnetic atoms Ce,Pr,Nd enhances Curie temperature TC while keeps the strong itinerant electron metamagnetic behavior. As a result, good magnetocaloric (MCE) properties appear in La0.7(Ce,Pr,Nd)0.3Fe11.6Si1.4 (LRFS) compound. The incorporation of interstitial H atom remarkably reduces hysteresis loss while increases TC to 314 K. The effective refrigeration capacity after deducting hysteresis can be increased by ∼128% upon H doping.

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