Enhancement of Electric Conductivity in Transparent Glass-Ceramic Nanocomposites of Bi2O3-BaTiO3 Glasses

The frequency and temperature dependent electrical conductivity measurements for heat-treated binary glass system with composition of (100-x)Bi2O3-xBaTiO3 (x = 20, 30, 40 and 50, in mol%) were carried out. The glass was prepared by melt quenching technique and their corresponding glass-ceramic nanocomposites were obtained by suitable heat treatment. Nanostructured behavior and electrical properties of these glasses and their corresponding glass-ceramic nanocomposites were studied. X-ray diffraction (XRD) and differential scanning calorimetry confirmed the amorphous nature of the glasses. Moreover, XRD patterns of the samples indicate nanocrystallites embedded in the glass matrix. The Fourier transform infrared spectroscopy (FT-IR) spectral analysis showed that the band positions of glass system are within the wave number range of BiO6, BiO3 and TiO6 structural units. It is observed that the electrical conductivity is enhanced by 102-103 times in the transparent glass-ceramic nanocomposite phase. With further heat treatment, the conductivity decreased considerably in the stage of glass-ceramic nanocomposite phase as compared with the glassy phase sample. Therefore, partially devitrified phase is more suitable as cathode material in secondary batteries compared to its vitreous or fully crystalline counterpart. The conduction mechanism was confirmed to obey the adiabatic small polaron hopping (SPH). AC conductivity measurements were performed as a function of temperature and frequency, showing a very slow increasing rate at low temperatures and then a fast rate at higher temperatures.