Connection between tunneling and localized configurational relaxations in glasses

Abstract

It is postulated that tunneling centers responsible for the low-temperature thermodynamic behavior of a glass are linked with those local regions where thermally excited orientational and/or translational diffusion occurs at T≤$T_g$ in an otherwise rigid glassy matrix. This postulate is tested by three sets of different experiments, namely, (i) physical aging, (ii) regions created in crystals by neutron irradiation, and (iii) regions created by addition of a second component to a glass, by using results from the literature. These results seem to confirm the postulate. The number of such local regions is ∼${10}^{16}$ per mole of a glass.