Anomalous small-angle X-ray scattering study of Tb_xCu_1-xand Gd_xCu_1-xamorphous alloys

Abstract

Anomalous small-angle X-ray scattering measurements were performed on as-sputtered TbxCu1-x (x=0.25 and 0.65) amorphous alloys below the Cu K edge and the Tb LIII edge, in order to determine the nature of the particles dispersed in the amorphous matrix. For technical reasons, measurements were also carried out on amorphous GdxCu1-x (x=0.29 and 0.7) and the isomorphous behaviours of the two alloys were checked. For the samples studied, the changes in the scattering ring intensity measured near both edges are consistent with the existence of rare-earth hydride particles, the associated decrease in the rare-earth concentration in the amorphous matrix being included in the anomalous scattering variations. From one sample to another, the hydride particles have radii of gyration ranging from 5 to 30 AA and occupy volume fractions from 5 to 20%. Their molecular volumes are close to that of the rare-earth trihydride (VREH3 approximately=40 AA3); some porosity in the hydride particles could explain the larger values (about 48 AA3) found in two samples.