Nanocrystallization as a method of improvement of electrical properties of Fe2O3-PbO2-TeO2 glasses

Selected glasses of Fe2O3-PbO2-TeO2 system have been transformed into nanomaterials by annealing at a temperature close to the crystallization temperature (T-c). The effects of the annealing of the present samples on the structural and electrical properties were studied by transmission electron micrograph (TEM), X-ray diffraction (XRD), differential scanning calorimeter, density (d) and dc conductivity (sigma). TEM and XRD of glass-ceramic naocrystals indicated nanocrystals embedded in the glassy matrix with average particle size of 20-35 nm. The glass-ceramic naocrystals obtained by annealing at T-c exhibit improvement of electrical conductivity up to four orders of magnitude than the starting glasses. This considerable improvement of electrical conductivity after nanocrystallization is attributed to formation of extensive and dense network of electronic conduction paths which are situated between Fe2O3 nanocrystals and on their surface. The conduction is attributed to non-adiabatic hopping of small polaron.