Conductivity enhancement in heterophase glasses after ion-exchange treatment

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