Structure of Glasses and Melts in the Na₂O-SiO₂-TiO₂ System

Abstract

In order to elucidate the influence of TiO₂ on the structure of sodium silicate glasses and melts, a MD (molecular dynamics) simulation using the ionic pair potential function, Born-Mayer-Huggins form, has been performed for 0.25Na₂O⋅0.47SiO₂⋅0.28TiO₂ glass and the corresponding melt. The calculation pair correlation functions were in good agreement with a RDF (radial distribution function) curve obtained from the previous structural analysis by TOF (time-of-flight) pulsed neutron scattering. The computer-simulated configuration for the glass indicated that most of Ti ions were in 4-fold coordination, whilst the remainder were 6-fold coordination. The frequency spectrum of the glass obtained from MD simulation was in good agreement with the Raman spectra measured on glasses in the Na₂O-SiO₂-TiO₂ system. As a result, the weak Raman band near 700cm^-1 can be assigned to Ti ion in 6-fold coordination, and the strong Raman band near 900cm^-1 reflects a Ti-O stretching band, which is characteristic of TiO₄ tetrahedra corner-linked with SiO₄ tetrahedra. The Raman spectra for glasses and melts in Na₂O-SiO₂-TiO₂ system were measured by the high temperature Raman spectroscopic technique. A slight difference in the obtained Raman spectra was observed between the glasses and the corresponding melts, implying that the structure of glass should be similar to that of the corresponding melt.