Thermal expansion of glasses at low temperatures
Gal'perin Yu. M. , Gurevich V. L. , Parshin D. A.
The thermal-expansion coefficient of a glass varies linearly with the temperature at low temperatures and is governed by the presence of two-level systems in the glass. The Gruneisen constant Γ is anomalously large (~ 102), because of the softness of the local atomic potentials in which the two-level systems occur. The primary component of the thermal-expansion coefficient is nonstationary, i.e., it depends on the experimental time t.