Temperature dependences of density of sodium borosilicate glasses in equilibrium states at temperatures below a vitrification temperature

The temperature dependences of the density and intensity of SAXRS of a variety of sodium borosilicate glasses in equilibrium states below vitrification temperature are obtained. The existence of a transition of the investigated supercooled liquids in a solid noncrystalline state was discovered that is similar to the one observed in the study of vitreous boron oxide and alkali-borate glasses. The temperature of the transition of supercooled liquids of the investigated compositions to a solid noncrystalline state is about 50°C below the vitrification temperatures determined by the SAXRS data. Thus, the transition occurs at a viscosity of 1014 P in borate and sodium borosilicate glasses.