A molecular dynamics study of the atomic structure of x(MgO) 100 − x(SiO2)

Abstract

A molecular dynamics study of magnesium silicate glasses was performed in order to study the local atomic environment of Mg in MgO–SiO2 with different composition. Molecular dynamics has been used to obtain models of (MgO)x(SiO2)100−x glasses with x=50,54,58,62 and 67, ~1000 atoms, and size~24Å. As expected, the models in the glass-forming region have a corner-shared tetrahedral silica network, SiO4, and Mg acts as a network modifier. The average coordination number of magnesium by oxygen was increased from 4.5±0.3 to 5.0±0.3 by increasing x from 50 to 67. There are~5% non-network oxygen for x=50 and the proportion increases up to 16% for x=67. Moreover, this study reported slight changes in Si–O and Mg–O environments; however, the changes in O–O correlations were noticeable in magnesium silicate glasses at pressures up to 9GPa.