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Polycrystalline samples of the α-quartz phase of GeO2 (q-GeO2), recovered from peak shock compressions of 5, 6.8, and 10 GPa, have been examined by x-ray diffraction, thermoluminescence, and Raman techniques. The measurements show that q-GeO2 irreversibly amorphizes above 6.8 GPa. The estimates of the shear band temperature suggest that the mechanism of shock-induced amorphization in q-GeO2 is a solid-solid one, in contrast to that in SiO2 quartz which has both solid-solid and fusion-quenched components.

This article describes the design, development, and performance testing of a versatile ultrahigh vacuum (UHV) electron-beam deposition system for synthesis of thin films and multilayer structures. Initially, basic design norms required to achieve set objectives are discussed and then a brief description of the system is presented. The fabricated UHV chamber has a number of vacuum ports to accommodate various features and accessories needed to deposit and characterize good quality thin films and multilayer structures of different metals. To demonstrate the capabilities of the system, depositions of thin films and multilayer structures of different materials were carried out. Representative results of hard x-ray reflectivity measurements corresponding to Ni, Au, and Ag thin films and Nb/Si and Fe/Ni multilayer structures are given and discussed. Furthermore, the easy adaptability of the system in order to carry out other investigations related to thin films is also demonstrated by presenting our recent in situ experiments conducted on aging studies of discontinuous silver films deposited on glass substrates under UHV conditions.

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