Investigation of polyamorphism in compressed BO glass by the direct measurement of the density

Brazhkin, V. V.*; Tsiok, O. B.*; Katayama, Yoshinori

Relative volume change of vitreous BO have been precisely measured by the strain-gauge technique at hydrostatic pressures up to 9 GPa. Smeared anomalies of compressibility (at P 0.5 GPa and P 5 GPa) and logarithmic relaxation of the glass density are observed. It has been revealed that there is a significant difference between the relaxed bulk modulus of glass obtained from the volume measurements and the unrelaxed modulus estimated from the Brillouin spectroscopic data. The basic features of the phase transitions in BO glass is revealed by the measurements of the relative volume change under compression together with the previous structure investigations and computer simulation results. Both direct and reverse transitions are smeared in pressure. The residual densification in glass is not associated with change in the short-range order.