Effect of composition, thickness and temperature on non-linear I-V curves in vanadium phosphate glasses

Glass layers of (V2O5)(1-x)(P2O5)(x) were prepared by melting appropriate mixtures of V2O5 and P2O5 powders. The measurements of I-V characteristic curves show three regions of conduction, namely high-resistance state, turnover point with zero-differential resistance region (partial derivative V/partial derivative I=0) and differential negative-resistance region. The turnover point is strongly dependent on composition, sample thickness and temperature. It is found that the increase of the ratio of phosphorus/vanadium reduces conductance as well as it raises the field required to produce turnover behaviour. The data in,the range up to the turnover point are discussed on the basis of an electrothermal process. Results of the negative-resistance state could be explained in terms of a hopping mechanism.