X-ray Diffraction Studies and Molecular Dynamics Calculations of the Structure of Alkali Disilicate Glasses

Abstract

The structures of K₂O⋅2SiO₂ and Li₂O⋅2SiO₂ glasses were investigated by the X-ray diffraction measurement. Their structures were determined by the pair function analysis of the radial distribution function and by the molecular dynamics calculation (for only K₂O⋅2SiO₂ glass). The structures of alkali disilicate glasses were shown to consist of layers of six-membered ring of SiO₄ tetrahedra with potassium or lithium ions occupying positions between them. Potassium ions and lithium ions were accomodated in the space formed by four non-bridging oxygen atoms of upper and lower layers. The layer structure of disilicate glass was recognized as a composite of chains of their corresponding metasilicate glasses. In analysis of the structure of K₂O⋅2SiO₂ glass, the molecular dynamics calculations were effective to obtain the most stable configuration. The result agreed with the previous study on Na₂O⋅2SiO₂ and Li₂O⋅K₂O⋅4SiO₂ glasses, which were determined to have the layer structures.