Role of Structural Relaxation in Peculiar
Permanent Densification of Fluorozirconate Glass.
Y. Tamai, Y. Kawamoto
J. Chem. Phys., 112, 3875-3883 (2000)
Abstract
Molecular dynamics simulations for a fluorozirconate glass
(55ZrF4 17BaF2 5EuF3 23NaF in mol %)
have been carried out in order to investigate a mechanism of
a peculiar high-pressure behavior in the permanent densification of
fluorozirconate glasses, which was found by experiments recently.
Simulation conditions mimic experimental ones;
compression of the glass under constant pressures at a high temperature,
quenching under constant pressures Pq, and then
decompression (release of pressure)
at constant temperatures Td.
The dependence of density on the quenching pressure Pq
exhibits a maximum,
which was also manifested in the experimental study.
A mechanism of this peculiar densification behavior is proposed in terms of
structural relaxation in the F- coordination environments
around the network modifying ions (Ba2+ and Na+)
during the decompression process.
The ``fragile'' nature of fluorozirconate glasses
plays an important role in this mechanism.
Copyright (c) 2000 Yoshinori Tamai