On the Debye-like behaviour of the specific heat of permanently densified silica glass

The aim of this work is to review the main results about the vibrational dynamics of glasses and to clarify the effect induced by changes of the mass density on their thermal properties. In particular, we present the temperature dependence of the specific heat of permanently densified silica glass in comparison to that of crystalline alpha-quartz. We propose a very simple and schematic model to interpret the experimental results.