Pressure dependence of density and structural relaxation of glass near the glass transition region

Abstract

AbstractA simplified and effective pressure cell together with an experimental procedure has been developed and applied to compress samples of SCHOTT N‐BK7® glass under static high pressures in a piston‐cylinder apparatus. Results from the density and volume recovery measurements show that, the glass samples were effectively densified in piston‐cylinder apparatus with the density at room temperature increasing linearly with frozen‐in pressure. To explain the experimental data, we developed a mathematical model based on a suggestion by Gupta (1988) with two internal parameters, named fictive temperature (Tf) and fictive pressure (Pf), which fits the experimental data well.