Electrical conductivity of ion-exchanged oxide glasses containing aluminium dispersoids

The effect of sodium ⇌ silver exchange on the electrical properties of glasses in the systems Na₂O-B₂O₃-SiO₂-Al and Na₂O-B₂O₃-Al have been investigated. In general, the ion-exchange step lowers the resistivity as well as the activation energy for conduction. The glasses have a highly inhomogeneous structure. The ion-exchanged glasses are characterized by a semi continuous silver-rich phase. These glasses can be switched to a highly conducting state by subjecting them to a critical electric field which varies from 0.2 to 5 vcm^-1 depending on temperature and the virgin glass composition. The resistivities in the highly conducting state have values in the range 3 to 10 Ω cm with activation energies varying from 0.002 to 0.008 eV. Wagner's asymmetric polarization cell measurements show that such high conductivity is electronic in nature.