EFFECT OF HALOGEN ON THE STRUCTURE AND IONIC-CONDUCTIVITY OF SILICATE-GLASSES

The density and ionic conductivity of the system (SiO2-Na2O-NaX), wher e X represents Cl-, Br-, and I-, are studied. Substitution of alkali h alide for alkali oxide is found to produce an open structure. The ioni c conductivity as well as the molar volume show an increase as the hal ogen content is increased. Glasses containing I- show higher conductiv ity than those containing Br- and Cl-. The density trend cannot be a c ompetition between the sizes of anions, rather it is assumed to be due to backing in the structure.