PHOTOEMISSION INVESTIGATION OF THE ELECTRONIC-STRUCTURE CHANGES IN ZR-NI-CU METALLIC GLASSES UPON HYDROGENATION

The electronic density of states (DOS) in the valence band of Zr50Ni50 -xCux metallic glasses (x = 10, 15, 17, and 20) and their hydrides was investigated by means of ultraviolet photoemission spectroscopy (UPS) . In the spectra, one could distinguish Cu-, Ni-, and Zr-derived state s both before and after hydrogenation. It was found that hydrogen mark edly modified the states mainly in the region of Cu-derived states whe reas the Ni- and Zr-derived states were affected to a lesser extent or in a different way by hydrogen. The effect of hydrogenation on the Cu -derived 3d valence-band states was ascribed to a hydrogen-induced pha se separation as a result of which the Zr-Ni-Cu metallic glass transfo rmed into a nanoscale mixture of Cu-rich clusters and copper-depleted Zr-Ni-Cu-H glassy hydride regions.