Correlation between electrical properties and microstructure of nanocrystallized V2O5–P2O5 glasses

It was shown that by thermal nanocrystallization of a 90V2O5·10P2O5 glass one can obtain a novel nanomaterial exhibiting enhanced electronic conductivity. Using a combination of methods: DTA, SEM, XRD and impedance spectroscopy (IS), it was possible to find correlation between microstructure and electrical properties of the obtained material and to optimize conditions of its synthesis. The room temperature electronic conductivity of the nanocrystallized samples is σ25 = 2 × 10−3 S cm−1 and is by a factor of 25 higher than the conductivity of the as-received glass. The nanocrystallized material is thermally stable up to ca 400 °C, which is about 150 °C above the glass transition temperature of the original glass. Maximum electronic conductivity of the thermally treated samples reaches 2 × 10−1 S cm−1 at ca 400 °C. The activation energy for these samples (0.28 eV) are substantially lower than that found for the starting glass (0.34 eV). The experimental results were discussed in terms of a model proposed in this paper and based on a “core-shell” concept. The results obtained here can be important for the progress in the search of novel nanocrystalline cathode materials for applications in Li-ion batteries.