Synthesis and Characterization of Eu3+-Doped Transparent Glass-ceramics Containing Nanocrystalline SrII NbIV O3.

The glass-ceramics containing a rarely achievable nanocrystalline SrII NbIV O3 phase in the 53.75 SiO2-18.25 K2 O-9 Bi2 O3-9 SrO-9 Nb2 O5-0.5 CeO2-0.5 Eu2 O3 (mol%) glass system were prepared by the melt-quench technique followed by a two-stage controlled heat treatment. The unusual oxidation state of Nb in SrII NbIV O3 crystal is 4+ and upon heat treatment of the samples at lower temperature of 500°C for several hours, the glass composition and chemical environment around Nb ions played a key role for the formation of SrII NbIV O3 in the glass-ceramics. The microstructure of the glass-ceramics was studied using TEM and FESEM. The TEM images advocate 10-40 nm crystallite size of SrII NbIV O3. FTIR study confirms that all the samples consist of SiO4, BiO3, BiO6, and NbO6 structural units. The refractive index at different wavelengths was found to vary in the range 1.7105-1.7905 and increase with increase in heat-treatment time. The luminescence spectra of Eu3+-doped glass and glass-ceramics were recorded at 465 nm excitation wavelength and the luminescence intensity is found to be increased with heat-treatment time due to increase in crystallinity. The high intensity ratio of 5D0→7F2 to 5D0→7F1 indicates that the Eu3+-doped nanocrystalline SrII NbIV O3 glass-ceramics are promising candidate materials as red-light source. [ABSTRACT FROM AUTHOR]