Abstract
Nanocrystalline Pd3Fe alloys with a grain size of 10 nm and 50 nm were pre-pared by dc-sputtering and ion-beam sputtering, respectively. The magnetic relaxation of hydrogen, i.e. the short-range diffusion of hydrogen, has been investi-gated. The sputter deposited films exhibit a broad relaxation spectrum, whereby the temperatures of the relaxation peaks depend on the hydrogen concentration. The topological and chemical environment of the hydrogen atoms is identified by their characteristic relaxation behaviour. In the nanocrystalline alloys hydrogen preferentially occupies sites within the grain boundaries. A comparison of these results with relaxation measurements of hydrogen in crystalline Pd3Fe alloys shows that the interstitial sites favoured by hydrogen are chemically surrounded by either one Fe and five Pd or two Fe and four Pd atoms. Furthermore, the sites are topologically disordered.