ELECTRICAL-CONDUCTIVITY OF FIELD-ASSISTED ION-EXCHANGED GLASS WITH MOLTEN PBCL2 SALT

Field-assisted ion-exchange was carried out between soda-lime-silica g lass tubes and molten PbCl2 at 823-degrees-K for 2 h under constant po tential of 12 V. The field-assisted ion-exchange leads to the formatio n of a lead-exchanged layer underneath the glass surface. The influenc e of the exchange on the bulk d.c. and a.c. electrical conductivity wa s investigated and compared with that of the glass before ion-exchange . The d.c. conductivity of the exchanged glass showed an activation en ergy higher than that of the glass before ion-exchange. The higher act ivation energy was attributed to the lower mobility of lead cations in the exchanged layer in comparison with that of sodium cations. The a. c conductivity of the exchanged glass showed an increase in the dielec tric constant and a decrease in the dielectric loss. These findings su ggest that lead cations enter the glass network in modifying positions in the exchanged glass. The results also support the data previously obtained that one lead cation from the molten PbCl2 replaced two sodiu m cations from the glass.