HYDROGEN REACTIVITY OF BARIUM GALLIOSILICATE AND RELATED GLASSES

Hydrogen treatment of barium galliosilicate glasses in the transformat ion temperature region results in composition, independent formation o f hydroxyl and visible darkening of the glass. Hydroxyl formation in t he high silica region is related to the concentration of (GaO4)- units and the oxygen stoichiometry of the glass, while in the low silica re gion, hydroxyl formation is independent of the concentration of (GaO4) - units. Although the hydrogen induced darkening of these glasses is a strong function of the impurity platinum concentration, the darkening behavior is also strongly influenced by glass composition. Hydrogen r eactivity studies of related glass systems, i.e. sodium galliosilicate and sodium and calcium aluminosilicate glasses, indicate that hydroge n reacts readily with galliosilicate glasses, but does not react with aluminosilicate glasses.