Computer Simulation of ‘Amorphase’ Diagram of Silica

A. Takada, Research Center, Asahi Glass Co. Ltd

It is well know that silica glasses have anomalous properties such as a density maximum and a densification. The magnitudes of such anomalous properties are different depending on temperature and pressure. Molecular dynamic calculations have been performed, varying both pressure and temperature. Glass structure can be changed through two routes. One is a vitrification route through quenching of supercooled liquids. The other is an amorphization route through compression in solid states.  By forming routes different glass structures are obtained. In this paper a type of graph (‘amorphase diagram’) is used to distinguish the stability conditions among different polyamorphic structures. The microscopic origins of different structural changes are also discussed.

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