Non-adiabatic small polaron hopping conduction in sodium borate tungstate glasses

Early stage nanocrystallization as a method of enhancement of electrical properties of lead/barium titanate doped vanadium borate glasses

Glass-ceramic nanocomposites (GCNs) of (10 - x) BaTiO3 (BT)-xPbTiO3 (PT)-60V2O5-30B2O3 with x = 0, 2.5, 5, 7.5 and 10 mol% were formed during heat treatment of conventional melt quenching glasses. X-ray diffraction was used to ensure glass and GCNs formation. Glasses and GCNs densities were measured by Archimedes principle. Fine polar clusters of lead titanate and/or barium titanate incorporation into vanadium borate glass matrix strongly depend on the composition. It was found out that the electrical conductivity of the initial glasses can be considerably improved by proper early stage of nanocrystallization at temperatures approaching the crystallization temperatures determined by DSC method. GCNs show massive increase in electrical conductivity (up to 6 orders of magnitude) as a function of BaTiO3 content. By increasing BaTiO3 content, the activation energy values have been found to increase. The enhancement in electrical conductivity of GCNs can be attributed to the increase in the crystalline phases in the glassy matrix which increases the concentrations of the V ion pairs.