Séminaire du Vendredi 27 Janvier 2012 à 11H

Molecular dynamics modelling of non-network oxygens in MgO-SiO₂ glasses

  Gavin Mountjoy (School of Physical Sciences, University of Kent, Canterbury CT27NH, UK)

IMPMC, Université P. et M. Curie, 4, Place Jussieu, 75005 Paris

Salle de Conférence, 4ème étage, Tour 23, Couloir 22/23 Salle 401

 Résumé :

Although Mg is not a major component of commercial silicate glasses, the role of Mg in silicate melts is important in mineralogy, and studies of magnesium silicate glasses are a key source of information.  Experimental studies in the literature give differing views on Mg coordination, and on the presence of oxygen not bonded to Si, which we refer to as "non-network" oxygen.  Results from our recent molecular dynamics modelling of MgO-SiO₂ glasses with two different sets of rigid ion potentials in meta- and ortho-silicate compositions will be presented [1]. This stimulates reflection on several issues such as the interpretation of previous NMR studies in the literature, the wider applicability of the bridging and non-bridging oxygen scheme for silicate structures, and the relationship between heterogeneity and phase separation.

[1] G. Mountjoy, B. M. Al-Hasni, and C. Storey (2011) J. Non-Cryst. Solids 357 2522 - "Structural organisation in oxide glasses from molecular dynamics modelling".