Universal behavior of internal friction in glasses below T : anharmonicity vs relaxation

TL;DR

This paper investigates the universal behavior of internal friction in glasses below their glass transition temperature, highlighting the roles of anharmonicity and relaxation processes across different materials.

Contribution

It provides a comparative analysis of internal friction at hypersonic frequencies, revealing universal features and the dominance of anharmonicity over relaxational processes at high temperatures.

Findings

Internal friction is weakly dependent on material at low temperatures.

Strong glasses exhibit a T-independent plateau in internal friction below Tg.

Fragile glasses show a nearly linear increase in internal friction with temperature.

Abstract

Comparison of the internal friction at hypersonic frequencies between a few K and the glass transition temperature Tg for various glasses brings out general features. At low temperature, internal friction is only weakly dependent on the material. At high temperature but still below Tg the internal friction for strong glasses shows a T-independent plateau in a very wide domain of temperature; in contrast, for fragile glass, a nearly linear variation of internal friction with T is observed. Anharmonicity appears dominant over thermally activated relaxational processes at high temperature.