| White light emitting diode (white LED) is becoming a new lighting application as its efficient energy use, environment friendly and long life. Of the approaches to creating white light, the model of phosphors together with ultraviolet LED can not achieve high ligh output, but the outstanding color quality decide its exciting application prospects. In the phosphors of this model, the rare earth doped silicate phosphor gains great interest due to their stability and optical properties. Glass ceramic, as the glass and crystal composites, owns the excellent luminescence properties from crystal phase and outstanding machinability, high uniformity and stability from glass phase.Sm3+, Tb3+, Eu2+doped CaO-MgO-Al2O3-SiO2 luminescent glass ceramics were prepared by melting-quenching and sintering method in this paper. X-ray Diffraction (XRD) and scanning electron microscope (SEM) were availed to measure the crystalline phase and microstructure of the glass ceramics. Jasco FP-6500 fluorescence spectrometer was used to get the emission and excitation spectra of samples. The color coordinates were measured by PMS-80 spectral analysis system. The structure of rare earth doped glass and glass ceramics were studied by XRD, XPS and Raman spectroscopy. And the crystallization of this glass was discussed by the kinetic analysis and fractal geometry. The results indicate:The crystallization manner of CaO-MgO-Al2O3-SiO2 glass is surface crystallization, and the possible main crystal is diopside or wollastonite. The crystal content of glass ceramic increased as heat treatment temperature or the time icreasing. For the diopside glass, RE3+exist in the glass as networkmodifier, after heat treatment, all the RE3+enter the diopside lattice and replace Ca2+sites.With the increase of reheat temperatures, RE3+concentration and the precipitate of diopside, the wavelength of peaks of Sm3+and Tb3+in optical spectra has no change. Sm3+doped glass ceramics can emit red light due to transitions 4G(?)→6HJ (J=5/2,7/2,9/2,11/2) under the excitation of long UV and blue lights. Tb3+doped glass ceramics emit intense cyan color light due to transitions 5D4,3→>7F6,5,4,3 under UV excitation. The luminescence of the glass ceramics is stronger than corresponding glass. We also found the direct correlation between luminescent intensity and crystal content, which was caused by the changed phonon energy. In the wollastonite glass ceramics, the luminescence intensity is increased with the increasing of the Sm2O3 or Tb4O7 content. In the diopside glass ceramics, concentration quenching effect was observed in the Sm3+doped glass ceramic, but not found in Tb3+doped glass ceramics.The flurescent spectras of Sm3+and Tb3+codoped glass ceramics under 350nm-385nm excitation were consist of the characteristic spectrim of Sm3+and Tb+ respectively. After excitaition of 350nm,355nm and 380nm LED, the color coordinates of the emission light fall within the white region of the 1931 CIE diagram, with low color temperatures of 1800-5400K.The Eu2+doped diopside glass ceramics could emit 442nm blue light under 355nm excitation. After heat treatment, short-wave-length shift and increased intensity were found in the luminescent spectra. With the increase of heat treatment time, the luminescence intensity increased. And the concentration quenching effect appeared with the increasing of the Eu2+content.In the matrix glass, the increased B2O3 induced separate phase, and another crystal cristobalite beta precipitated. The luminescent intensity of Sm3+and Tb3+doped glass ceramics increased firstly and then decreased with the increasing of the B2O3 content.The addition of reductant to the diopside glass inhibits the surface crystallization, and the crystallization process could be described by Diffusion-Limited Aggregation model.This work was supported by the Science and Technology Project of Hubei (20091g0041).
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