HELIUM PERMEATION, DIFFUSION AND SOLUBILITY IN SODIUM GALLIOSILICATE GLASSES

Helium permeability, diffusivity and solubility have been determined f or four series of sodium galliosilicate glasses. The results are compa red to literature data for sodium aluminosilicate and lithium galliosi licate glasses. Replacement of silica by gallium oxide decreases the h elium permeability of glasses containing constant concentrations of so da but replacement of soda by gallium oxide increases the helium perme ability of glasses containing a constant concentration of silica. Corr esponding effects occur for the helium diffusivity and solubility in t hese glasses. There is no significantly effect on helium permeability due to replacement of gallium oxide by alumina for glasses containing equimolar concentrations of soda and an intermediate oxide. Sodium gal liosilicate glasses are approximately an order of magnitude more perme able that are the corresponding lithium galliosilicate glasses.