Effect of thermal treatments on the low temperature specific heat of B2O3 and SiO2 glasses

Abstract
Specific heat measurements have been performed between 0.1 and 1 or 2 K on B2O3 and SiO2 glasses, which were stabilized near Tg by thermal treatments. Although permanent variations of the density up to two per-cent were obtained for B2O3, this induced only a slight modification of the specific heat related to the two-level systems