Study on the homogeneity of hydrogenation for LaFe11.5Si1.5 intermetallic compound

The homogeneity of hydrogen absorption for LaFe11.5Si1.5 intermetallic compound was investigated. The hydrides remained NaZn13-type structure when the hydrogenation temperature varied from 423 K to 923 K under 1 atm hydrogen atmosphere. The Differential Scanning calorimetric (DSC) measurements revealed slightly inhomogeneous distribution of hydrogen atoms in the hydrides hydrogenated at a low temperature. The activation before hydrogenating at a higher temperature could improve the homogeneity of hydrogen absorption. Uniform magnetic transition temperature, corresponding to the homogeneous hydrogen absorption, was observed by hydrogenating the compound at 823 K, or at 523 K after activation. The maximum magnetic entropy change ΔSM (ΔH=2 T) for the compound hydrogenated at 823 K is about 15.5 J/kg K with the latent heat of 5.12×103 J/kg during the phase transition