Giant magnetic entropy change in hydrogenated La(Fe0.88Si0.12)13Hy compounds

A magnetic entropy change DeltaS(M) due to the itinerant-electron metamagnetic (IEM) transition was estimated to be -23 J/kg K around the Curie temperature for La(Fe0.88Si0.12)(13) in the magnetic field change front 0 to 5T. In order to control the Curie temperature while keeping such a large value of DeltaS(M), hydrogen absorption was carried out. La(Fe0.88Si0.12)(13)H-1.0 with T-C = 274 K shows a large DeltaS(M) due to the IEM transition around room temperature. The adiabatic temperature change DeltaT(ad) front 0 to 2 T is about 7 K, comparable to that of Gd-5(Ge0.5Si0.5)(4). By changing the hydrogen concentration. the Curie temperature can be controlled from 195 to 336 K. It should be noted that the magnitude of DeltaS(M) is almost the same after hydrogen absorption. Therefore, the hydrogenated La(Fe0.88Si0.12)(13)H-y compounds are promising magnetic refrigerants working in a wide range of temperature.