Amorphous germanium (a-Ge) structure is known to show a complex behavior upon pressurization. Here an XAS experiment on a-Ge at high pressure and temperature is presented, which is aimed to investigate such behavior and verify the presence of "polyamorphism". High quality a-Ge EXAFS spectra (Ge Kedge) have been collected up to 8.3GPa. The data analysis, realized using the GNXAS package, gives precise values of the first neighbor bond lengths at various pressures. Two well defined behaviors of the a-Ge local atomic structure have been observed, depending on the sample temperature. At 475Ka-Ge starts to crystallize above 8GPa. On the other hand, at room temperature, the data seem to indicate the occurrence of a transition toward a different amorphous structure, well before the start of the process of crystallization.

Pressure induced phase transitions in amorphous Ge

DI CICCO, Andrea;
2005

Abstract

Amorphous germanium (a-Ge) structure is known to show a complex behavior upon pressurization. Here an XAS experiment on a-Ge at high pressure and temperature is presented, which is aimed to investigate such behavior and verify the presence of "polyamorphism". High quality a-Ge EXAFS spectra (Ge Kedge) have been collected up to 8.3GPa. The data analysis, realized using the GNXAS package, gives precise values of the first neighbor bond lengths at various pressures. Two well defined behaviors of the a-Ge local atomic structure have been observed, depending on the sample temperature. At 475Ka-Ge starts to crystallize above 8GPa. On the other hand, at room temperature, the data seem to indicate the occurrence of a transition toward a different amorphous structure, well before the start of the process of crystallization.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11581/237438
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