Effects of Mono- and Divalent Cations on the Properties of Multicomponent Phosphate Glasses

The effects of mono- and divalent cations on the properties of multicomponent phosphate glasses were investigated. The Tg, Yp and α were increased with increasing ionic radius of the alkali ion. As a result, the water durability of the phosphate glasses was improved. An introduction of divalent cations also resulted in the same tendency. It is evident from the IR measurement that the coordination number of cross-linking cations is increased with increasing ionic radius of the cation, and as a result, the bonding strength between cations and oxygen was weakened. It is considered that the improvement of the water durability is due to the increasing linking density, which is accompanied by increasing steric hindrance of the additional cations against attack by water molecules.