Effects of Devitrification on Electrical Properties of Phosphate Glasses Containing Titanium Ions

Abstract

Effects of devitrification on electrical properties of glasses were studied. Before and after devitrification of phosphate glasses containing titanium ions, electrical conductivities, dielectric constants and tan δ were measured. The results are summarized as follows.The conductivity increased and the activation energy for conduction decreased after devitrification. The amount of these changes increased with the degree of devitrification in the same composition.The dielectric constant and tan δ increased and this tendency was more remarkable at lower frequencies.The above-mentioned phenomena were likely to be attributed to the valence exchange of coexisting Ti3+ and Ti4+ ions, which was enabled more readily to occur in the liberated crystal phases. In fact, the same phenomena were observed in case of phosphate glasses containing wolfram ions, where W5+ and W6+ are supposed to be coexisting.The addition of small quantity of iron ions acted to suppress the increase in conductivity of devitrified glass.In devitrified glass, the log σ-1/T curve was not always linear. Where the residual glassy phase existed, it approached gradually to the line of the original glass with increasing temperature.