Hydrogen-induced amorphization and its effect on magnetic properties of the Laves-phase GdFe2 compound

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Abstract
The influence of hydrogenation on the structural change and magnetic properties of the Laves‐phase GdFe2 compound has been investigated. Crystalline c‐GdFe2 absorbs 4.4 hydrogen atoms per formula unit without any change in the crystal structure below 423 K. On the other hand, GdFe2 transforms to amorphous a‐GdFe2H3.6 by hydrogenation from 423 to 523 K, where the decomposition of GdFe2 into GdH2 and α‐Fe is prevented. The same amount of hydrogen (3.6 atoms per formula unit) dissolves in amorphous alloys produced by both hydrogenation and rapid quenching. Hydrogenation sharply reduces the Curie temperature of the crystalline alloy from 818 to 107 K, in contrast to the Curie temperature of 443 K for the hydrogen‐induced amorphous alloy. The temperature dependence of the magnetization of the hydrogen‐induced amorphous alloy is identical to that of the hydrogenated rapidly quenched amorphous alloy, suggesting similarity of their structures. The magnetization of the hydrogen‐induced amorphous alloy shows a broad peak around 300 K. Above 300 K the magnetization of the amorphous alloys is largely uninfluenced by hydrogen. Below the peak it is reduced by hydrogenation.