Structure of lithium borate and strontium borate glasses with high modifier contents

The structure of lithium borate and strontium borate glasses with high Li₂O and SrO contents was examined using the experimental results of ESR and the optical absorption of Cu²⁺ ions, and the Mössbauer spectra of Fe³⁺ ions and Raman spectra of these glasses. The results indicate the existence of non-bridging oxygens belonging to orthoborate and pyroborate groups, structural groups of diborate and high pressure forms of metaborate above 30 mol% of the modifier contents in these glasses. Among these four structural groups, the diborate group rapidly decreased with an increase of the modifier contents, while the other three groups increased with an increase of the modifier contents.