Synthesis and characterization of Eu3+-doped transparent glass-ceramics containing nanocrystalline (SrNbO3)-Nb-II-O-IV

The glass-ceramics containing a rarely achievable nanocrystalline (SrNbO3)-Nb-II-O-IV phase in the 53.75SiO(2)-18.25K(2)O-9Bi(2)O(3)-9SrO-9Nb(2)O(5)-0.5CeO(2)-0.5Eu(2)O(3) (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 (SrNbO3)-Nb-II-O-IV crystal is 4+ and upon heat treatment of the samples at lower temperature of 500 degrees C for several hours, the glass composition and chemical environment around Nb ions played a key role for the formation of (SrNbO3)-Nb-II-O-IV in the glass-ceramics. The microstructure of the glass-ceramics was studied using TEM and FESEM. The TEM images advocate 10-40nm crystallite size of (SrNbO3)-Nb-II-O-IV. 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 465nm 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 (D0F2)-D-5-F-7 to (D0F1)-D-5-F-7 indicates that the Eu3+-doped nanocrystalline (SrNbO3)-Nb-II-O-IV glass-ceramics are promising candidate materials as red-light source