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Amorphous and crystallized Ni84Y8Kr8 samples have been examined by the small angle X-ray scattering technique. The size of Kr bubbles in the amorphous sample was estimated to be about 20 Å. The size increased with increasing annealing temperature and annealing time.

The structural studies of amorphous Ni84Y8Kr8 alloy have been performed by means of X-ray diffraction combined with DTA/TG, TEM and SEM experiments. The local structure of this amorphous alloy appears to be well represented by a mixture of noncrystalline microstructures with short-range interatomic distances similar to crystalline Ni9.4Y, Ni and Kr. The X-ray diffraction pattern at 300°C demonstrated the occurrence of crystallization. Initially, the diffraction peaks can be indexed as a mixture of Ni9.4Y and Ni phases, and Ni9.4Y decomposes into Ni and Ni5Y at higher temperatures. X-ray diffraction measurements exhibit the formation of solid fcc Kr bubbles or precipitates above 540°C. The rapid release of Kr does not occur below 700°C.

The electronic structure of amorphous germanium (a-Ge) is considered using a tight-binding scheme with all first-neighbor couplings in a continuous random network. The dihedral-angle and bond-angle disorders are found to be important a t the valence-band-edge and responsible for the observed features near the top of the valence band. A t the top of the valence band of a-Ge a tail of localized states e 0.4 eV in width is found.Es wird die elektronische Struktur von amorphem Germanium (a-Ge) mit einem ,,tight-binding"-Schema mit allen Kopplungen nachster Nachbarn in einem kontinuierlichen statistischen Netzwerkmodell untersucht. Es wird gefunden, da13 die Dihedralwinkel-und Bindungswinkelfehlordnungen an der Valenzbandkante wesentlich und fiir die beobachteten Einzelheiten in der Nahe des Valenzbandmaximums verantwortlicli sind. Es wird am Ma,ximum des Valenzbandes von a-Ge ein Auslaufer von lokalisierten Zustanden mit etwa 0,4 eV-Breite gefunden.