Conductivity enhancement in heterophase glasses after ion-exchange treatment

Abstract

The effect of sodium to or from silver ion exchange on electrical conductivity has been investigated for some heterophase glasses containing bismuth oxide. The electrical resistivity in ion-exchanged samples decreases by several orders of magnitude when they are subjected to an electrical field of about 10-30 V cm⁻¹ at around 300°C. Polarisation experiments carried out on samples in such a highly conducting state show that the electrical transport is ionic in nature. The switching to these states is believed to arise as a result of the growth of a silver-rich phase to a percolation configuration. The resistivities of these phases are in the range 10-10³ Ω cm with low activation energy values. The results suggest that these materials may constitute a new class of superionic conductors.