Structure of Sodium Gallotitanate Glass in Relation to Glass Formation

Abstract

The structure of 40NaO_0.5⋅20GaO_1.5⋅40TiO₂ glass has been investigated by X-ray radial distribution analysis. Nearly all the Ga³⁺ and Ti⁴⁺ ions are four coordinated, constructing highly cross-linked three-dimensional glass networks, and that the number of non-bridging oxygens is very small. The degree of medium-range order in this glass is much lower than in the Na₂O⋅2TiO₂ glass studied in a previous paper, possibly due to the almost complete absence of TiO₆ octahedra in the former glass. The higher glass-forming ability of the Na₂O-Ga₂O₃-TiO₂ ternary system compared with the Na₂O-TiO₂ binary system is ascribed mainly to the higher fraction of four-coordinated Ti⁴⁺ ions in the former system. It is suggested that in oxide systems glass-forming ability increases with increasing fraction of four-coordinated Ti⁴⁺ ions.