EFFECTS OF MONOVALENT AND DIVALENT-CATIONS ON THE PROPERTIES OF MULTICOMPONENT PHOSPHATE-GLASSES

The effects of mono- and divalent cations on the properties of multico mponent phosphate glasses with the compositions of 10PbO . 20ZnO . 10R (2)O . 50P(2)O(5) . 7.5Al(2)O(3) . 2.5B(2)O(3) (R: Li, Na, K, Rb) and 10PbO . 20ZnO . 5Li(2)O . 5R'O . 50P(2)O(5) . 7.5Al(2)O(3) . 2.5B(2)O( 3) (R': Mg, Ca, Sr, Ba, Zn, Cd, Sn, Ph) were investigated. Glass trans ition temperature (T-g), yielding point (Y-p), and thermal expansion c oefficient (alpha) increased with increasing ionic radius of the alkal i ion. As a result, water durability of the phosphate glass was highly improved. introduction of divalent cations also resulted in the same tendency. It was considered that the improvement of the water durabili ty was due to the increasing linking density, which was accompanied by increasing steric hindrance of additional cations against attack by w ater molecules.