Physical Properties Of Sodium Borogermanate Glasses Compared With The Sodium Borosilicate System

The glass forming range of the sodium borogermanates was examined as a function of R (molar ratio of soda to bora) for fixed K families (where K is the molar ratio of germania to bora). Glass formation has been extended to 70 mol% soda well beyond that previously reported. Density and the glass transition temperature (Tg) were measured on a large number of samples spanning the newly observed glass forming limits. The resulting property trends are discussed in terms of models for the automatic arrangement. Key comparisons are made between this system and the corresponding technologically important sodium borosilicates.