WHAT ARE GLASSES REALLY LIKE?

摘要

Recent examinations of the structure of oxide glasses, chiefly by neutron scattering with isotopic contrast variation are reviewed to assess the extent of local and medium-range ordering and the validity of comparisons with the structures of crystals and liquids. The presence of two-dimensional structures in some silicates is inferred and this result is considered in the light of "quasi-Bragg" planes recently proposed to explain first sharp peaks in the diffraction data for vitreous silica and similar glasses. Generalisation to silicates containing alkali and alkaline earth elements is demonstrated with suggestions for further, crucial, experiments.