Brillouin light scattering has been used to determine the high-frequency complex mechanical modulus of alkali tellurite liquids and glasses, as a function of the temperature. In order to adequately describe the temperature dependence of this modulus, a modified Maxwell model for linear viscoelastic systems was developed. Accordingly, the modulus comprises relaxational components and a temperature-dependent static modulus, the magnitudes of which are determined by the equilibrium volume fraction of kinetically arrested domains. In binary alkali tellurites the structure degrades with increasing temperature by means of the dissolution of network rings, which involves the conversion of (Formula presented) trigonal bipyramids into (Formula presented) trigonal pyramids. This decrease in network connectivity is believed to be responsible for the decrease in the elastic modulus and to cause the release of structural components into a viscoelastic state. At high temperatures structural dynamics can be described with a single relaxation time.
|Original language||English (US)|
|Number of pages||12|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jan 1 1998|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics