Journal of the American Ceramic Society, Vol.95, No.10, 3056-3063, 2012
Transparent Eu3+-Doped Ferroelectric Bismuth Titanate Glass-Ceramic Nanocomposites: Fabrication and Properties
Bismuth titanate (Bi4Ti3O12) (BiT), glass is prepared by the melt-quench technique in the SiO2K2OBi2O3TiO2 (SKBT) system doping with Eu2O3 and transparent BiT glass-ceramics (GC) is derived from it by controlled heat-treatment at 500 degrees C by varying duration. The structural properties of the heat-treated GC are investigated using X-ray diffraction (XRD), electron microscopy [Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM)], and fourier transform infrared reflectance spectroscopy. FE-SEM and TEM images show the formation of polycrystalline spherical particles of 100200 nm with 1015 nm crystallites after heat-treatment. A significant increase in er value (from 20 to 35) was observed with increase in heat-treatment time. The transmission losses of GC which happened with heat-treatment time are due to Rayleigh scattering exhibited by nanocrystallites of BiT. The excitation spectra have been recorded by monitoring emission at 612 nm corresponding to the 5D0 -> 7F2 transition and an intense 467 nm excitation band corresponding to the 7F0 -> 5D2 has been observed. Emission spectra were recorded by exciting the glass samples at 467 nm. It is observed that with increase in heat-treatment time, the intensity of red emission at 612 nm increases by 8-fold, which has happened due to the occupancy of Eu3+ ions in the low phonon energy crystal sites of BiT.