ALKALI AND ALKALINE-EARTH GALLIOSILICATE GLASSES

This chapter discusses the formation, properties, and structures of oxide glasses containing gallium oxide, either an alkali or alkaline earth oxide, and a glassforming oxide. Glassforming regions in the lithium, sodium, potassium, calcium, and barium galliosilicate systems are presented. Studies of the atomistic and morphological structures of these glasses will also be discussed. The effects of gallium oxide additions on the properties of alkali and alkaline earth galliosilicate glasses are discussed in detail and are compared with those due to alumina where appropriate, including a discussion of the mixed intermediate effect. The effect of the identity and concentration of the alkali or alkaline earth oxide present on the properties of these glasses is addressed, with emphasis on the effects of ionic radius and mass of the modifier ion on these properties. Properties considered include density, refractive index, thermal expansion behavior, viscosity and glass transformation temperatures, electric conductivity, chemical durability, and helium permeability. The reaction of galliosilicate glasses with molecular hydrogen will also be discussed.