Basicity variation in network oxides: Distribution of metal ion sites in borate glass systems

Ultraviolet probe ion and far-infrared spectroscopic results for barium borate glasses indicate the existence of two types of cation-hosting site differing in electron density, that is, basicity. The pattern is similar to the sodium borate glass system, which has the same average theoretical optical basicity trend. However, the basicity span for the bipositive ions is less than for the monopositive, and this is explained in terms of the partial charge neutralization effected by the oxide(-II)/metal ion interaction, roughly in accordance with Pauling's electroneutrality principle. The results explain abnormal optical basicity values reported previously for studies involving electrolysis of glass and the effect of temperature.