Multilayered La_0.7Ce_0.3Fe_11.6Si_1.4/Fe composites and their hydrides for magnetic refrigeration near room temperature

Magnetocaloric composites with alternately stacked Fe layers and porous La_0.7Ce_0.3Fe_11.6Si_1.4 layers were prepared by powder metallurgy. Such a multilayered structure allows the composites to transfer heat faster in the parallel direction to Fe layers than the perpendicular one and maintain a mechanical stability during hydrogenation. Thermal conductivity differences between the two directions at 300 K are 4.1 W/m K for the La_0.7Ce_0.3Fe_11.6Si_1.4/Fe composites and 2.0 W/m K for their hydrides. The hydrides exhibit a large entropy change of 12.3 J/kg K and a temperature change of 2.1 K under a low magnetic field change of 1 T near 316 K. Besides, the temperature change of the hydrides remains almost constant during 10,000 continuous magnetic cycles. The highly anisotropic thermal conductivity, large magnetocaloric effect and good fatigue resistance make these multilayered composites potential candidates for the application as high-performance magnetic refrigerants.