A molecular dynamics study of densification mechanisms in calcium silicate glasses CaSi2O5 and CaSiO3 at pressures of 5 and 10 GPa

Mead, RN and Mountjoy, G. (2006) A molecular dynamics study of densification mechanisms in calcium silicate glasses CaSi2O5 and CaSiO3 at pressures of 5 and 10 GPa. Journal of Chemical Physics, 125 (15). ISSN 0021-9606. (The full text of this publication is not available from this repository)

The full text of this publication is not available from this repository. (Contact us about this Publication)
Official URL
http://dx.doi.org/10.1063/1.2360272

Abstract

Molecular dynamics is used to obtain models of (CaO)x (Si O2) 1-x glasses, with compositions Ca Si2 O5 (x=0.33) and CaSi O3 (x=0.50), at pressures of 5 and 10 GPa. At 5 GPa there are increases in Ca and Si coordinations for x=0.33, whereas for x=0.50 there is distortion of Ca ON polyhedra but no substantial change in coordination. At 10 GPa the Ca coordination increases by ∼20% for x=0.33 and by ∼10% for x=0.50. This increase is due to increased Ca bonds to bridging oxygens (Ob), since nonbridging oxygens (Onb) are already highly bonded to Ca, and the proportion of Onb is decreasing due to changes in the silica network. At 10 GPa there are ∼20% of fivefold and a few percent of sixfold coordinated Si. Since the new Si-O bonds involve the conversion of Onb to Ob, there is a corresponding increase in the network connectivity. The x=0.50 glass is more resistant to deformation because there is less possibility to convert Onb to Ob due to lower Si content. The changes in Ca-O, Si-Ca, and Ca-Ca correlations are predicted to produce changes in the x-ray diffraction structure factor S (Q), including a shift of the first sharp diffraction peak to higher Q values

Item Type: Article
Uncontrolled keywords: Chemical bonds; Composition; Densification; Glass; Molecular dynamics; Pressure effects; Coordination; Network connectivity; Silicate glasses; Sixfold coordination
Subjects: Q Science > QC Physics
Divisions: Faculties > Science Technology and Medical Studies > School of Physical Sciences
Depositing User: Sara Witchell
Date Deposited: 19 Dec 2007 18:33
Last Modified: 25 Jan 2013 13:49
Resource URI: http://kar.kent.ac.uk/id/eprint/875 (The current URI for this page, for reference purposes)
  • Depositors only (login required):