Effect of Pressure on the Structure of SiO2 at the Glass Transition Temperature

The structural transformation of Silica system under compression at glass transition temperature (1475 K) investigated by molecular dynamics method. The structural features such as pair radial distribution function, coordination number, linkage and cluster distribution analyzed systematically. The tetrahedral coordination (SiO4) maintained up to pressure of 5 GPa. Under compression, the structure tends to transit gradually from tetrahedral- to octahedral- coordination (SiO6) via pentahedral ones (SiO5). At pressure beyond 30 GPa, most of Si cation have octahedral coordination. The structural transitions at high-temperature models (1475 K) occurred at pressure higher than that at low temperature ones (500 K). In the 10–20 GPa range, the structure of model consisted of two large clusters of SiO5 and SiO6 revealing the structural homogeneity.