Large magnetocaloric effects in NaZn13-type La(FexSi1−x)13 compounds and their hydrides composed of icosahedral clusters

Abstract

The magnetocaloric effects (MCEs) in cubic NaZn13-type La(FexSi1−x)13 compounds and their hydrides composed of icosahedral clusters have been investigated because these compounds exhibit the itinerant-electron metamagnetic (IEM) transition just above the Curie temperature Tc: The value of Tc can be increased continuously up to about 336 K by hydrogen absorption into the La(FexSi1−x)13 compounds. Therefore, the values of the isothermal magnetic entropy change ∆Sm and the indirectly estimated adiabatic temperature change ∆Tad due to the IEM transition become -31 J/kg K and 15.4 K, respectively, in the magnetic field change from 0 to 5 T at Tc = 287 K for the La(Fe0.90Si0.10)13H1.1 compound. The MCEs in the compounds having the IEM transition are much larger than thosein the compounds exhibiting the second-order magnetic transition at Tc: The direct measurement of the adiabatic temperature change has confirmed such a large value. Consequently, the La(FexSi1−x)13 compounds and their hydrides having the IEM transition are promising as high performance magnetic refrigerants working in a wide temperature range covering room temperature in relatively low magnetic fields.