Formation and properties of sodium scandium silicate glasses

Sodium scandium silicate glasses can be formed containing a maximum of approximately 15 mol% Sc2O3. The addition of scandium oxide to these glasses increases their density, refractive index and glass transformation temperature. The glass transformation temperatures of these glasses approach 800 degrees C for glasses containing 10-15 mol% Sc2O3. Replacement of silica by scandium oxide significantly reduces the helium permeability and slightly decreases the electrical conductivity of these glasses. Glasses containing scandium oxide have higher glass transformation temperatures than corresponding glasses containing Y2O3 or Er2O3. The density of corresponding glasses containing Sc2O3, Y2O3 or Er2O3 increases with increasing atomic weight of the cation. Results of this study indicate that scandium ions act as network cations increasing the connectivity of the vitreous network.