On the increase of thermal conductivity in glasses above the plateau region

Abstract

Hopping of localized vibrational states in glassy systems via vibrational anharmonicity, C eff, provides an additional heat-carrying channel. The associated thermal conductivity, κ hop( T), increases linearly with increasing temperature T in the regime where vibrational lifetimes are reasonably long. Recent work of Yamaguchi et al. has shown that, for a- GeS 2, C eff for the strongly localized states associated with the Bose peak is at least 20 times larger than the acoustic anharmonicity C 111. Insertion of this value into the theoretical expression for κ hop( T), along with accepted values for the other parameters, yields a magnitude for κ( T) quite comparable to that found for network-forming glasses above the plateau temperature.