PROPERTIES AND STRUCTURE OF RO-NA2O-AL2O3-P2O5 (R=MG, CA, SR, BA) GLASSES

The properties acid structure of (45 - x)RO . xNa(2)O . 2.5Al(2)O(3) . 52.5P(2)O(5) (R - Mg, Ca, Sr, Ba, O less than or equal to x less than or equal to 31 mol%) glasses were investigated. The variation in the molar volumes of glasses in the MgO series is closely related to the f ormation of the end groups in the glasses with the substitution of Na ions for Mg2+ ions, resulting in a variation of the density and refra ctive index of the glasses. The properties of glasses containing CaO i n terms of Na2O substitution depend mainly on the low field strength o f Na+ ions substituting for CaO even though the end groups occurring i n the glasses increased. The variation in properties of the glasses co ntaining SrO and BaO, some of which were substituted by Na2O, could be explained by differences in masses, field strength and polarizability between the Na+ ions and the alkaline-earth ions due to a small varia tion in the structure of the glasses despite Na2O substitution.