W0063

Polymorphism in Amorphous Materials: Effect of Pressure and Temperature. M. Grimsditch, Materials Science Division, Argonne National Laboratory, Argonne IL

The structural changes in amorphous materials produced by pressure or temperature are reflected in the vibrational properties. However, contrary to structural changes which are often hard to measure, the changes in vibrational properties are often substantial and can easily be detected. Raman and Brillouin scattering have been used to probe the irreversible changes induced in a-SiO ₂, a-GeO ₂ and a-B ₂O₃ by pressure and temperature. Although the observed irreversible modifications are ascribed to ‘polymorphic’ structural changes, the nature of the microscopic rearrangements can seldom be extracted from the vibrational data without extensive modeling. Work supported by the US DOE, BES.