Molecular dynamics simulation of permanent densification of fluorozirconate glass

Molecular dynamics simulations for a fluorozirconate glass (55ZrF4·17BaF2·5EuF3·23NaF in mol%) have been carried out to investigate the mechanism of a peculiar high-pressure behavior in the permanent densification of fluorozirconate glasses, which was recently found by experimental investigation. Experimental conditions in simulations are mimicked by compression of the glass at high temperature, quenching under constant pressures, and then decompression (release of pressure) at constant temperatures. The dependence of density on the quenching pressure exhibits a maximum, which was also found in the experimental study. This peculiar behavior is interpreted in terms of structural relaxation in the F− coordination environments around metal ions in the decompression process of glass.