Electrical conductivity of lithium phosphate glass-ceramics precipitated with nanocrystalline BaTiO3

摘要

A series of lithium phosphate glass-ceramics dispersed with ferroelectric BaTiO3 nanocrystals were synthesized by a high energy ball milling technique in view of the fact that this technique is being successfully used to produce nanocrystalline powders. X-ray diffraction (XRD) peaks corresponding to nanocrystalline phases such as BaTiO3, BaTiP2O3, TiO2, and Li4P2O7 are observed in all the LPBX glass-ceramic samples. The average crystallite sizes obtained from XRD traces are in good agreement with the values evaluated from SEM images. Raman spectra of BaTiO3 nanoparticles confirm their tetragonal structure with a non-regular octahedron formation which is due to the presence of hydroxyl related groups and Ba2+ vacancies. The bands observed in the Raman spectra of Li2O-P2O5:BaTiO3 glass-ceramic samples at 351, (151, 464, 448) and 1189 cm(-1) revealed the presence of major nanocrystalline phases such as Li4P2O7, BaTiO3 and TiO2 which are confirmed by XRD results. The bulk conductivity is the highest for the LPB15 glass-ceramic sample (sigma=1.414x10(-7) S/cm) at 303 K whereas the activation energy (E-a sigma=0.445 eV) and power exponent (s=0.352) are lowest among all the samples under investigation.