Studies of Chemical Bonding in Glasses by X‐Ray Emission Spectroscopy

Abstract

Silicon and aluminum K β band X‐ray emission spectra of a series of lithia‐aluminosilica (LAS) glasses were determined using the X‐ray spectrometric systems of commercially available electron microprobes. Comparison with spectra of reference materials, including glassy and crystalline forms of silica, high‐quartz‐phase crystals of the L:A:S‐1:1:2 (mol ratio) composition (high‐eucryptite), and 6‐ and 4‐coordinated aluminum oxides, led to tentative assignment of spectral peaks to specific electronic transitions. Molecular orbital theory and crystallographic structural data were used to assign bands in crystalline materials. The LAS glass spectra indicated progressive bond weakening with decreasing silica content; the K β peak shifts permitted approximate calculation of the decreases in Si–O and Al–O bond energies, which were as great as 30 kcal/mol relative to SiO 2 (for the L:A:S‐1:1:2 glass).