Elaboration And Luminescent Properties Of Rare-Earth Phosphate-Baesd Glass Ceramics

Since rare-earth (RE) ions doped glass ceramics exhibit lager stimulated emission cross section, long radiative lifetime and high solution for RE ions, and possess many potential application in laser materials, scintillators, fiber amplifiers, white light emitting diodes (W-LEDs) and so on, RE ions doped glass ceramics have been investigated and developed extensively. In this thesis, the main contents are listed as follows:1. Eu-doped transparent glass ceramics containing YPO4nanocrystals were firstly prepared by conventional melt-quenching technique and heating treatment. The nominal composition of glass was43SiO2-22Al2O3-18Na2CO3-3NaF-10YF3-4P2O5(in mol%). Their microstructure and luminescent properties were investigated by X-ray diffraction (XRD), Transmission electron microscopy (TEM), absorption spectra, excitation and emission spectra, as well as fluorescence decay curves. The results of XRD and TEM reveal that spherical YPO4nanocrystals are distributed homogeneously among the glass matrix, and the mean crystallite size of YPO4nanocrystals is about20nm. In glass ceramics, the prominent Stark splitting, low forced electric dipole5D0â†'7F2transition and long decay lifetimes of Eu3+emission all demonstrated that Eu3+had entered into YPO4nanocrystals, while Eu2+still reside in glass matrix. In addition, the significant enhancement of Eu2+emission with increasing crystallization temperature was observed in glass ceramics, and the fluorine evaporation causes the reduction of Eu3+to Eu2+. Excited by365nm light, blue white luminescence was obtained in glass ceramics by combining the emission of Eu3+and Eu2+. Our results indicate that YPO4based glass ceramics doped with RE ions may find application in photonics. 2. Eu/Tb single doped and co-doped glass ceramics containing GdPO4nanocrystals were prepared by melt-quenching technique and heating treatment. The nominal composition of glass was43SiO2-22Al2O3-18Na2CO3-3NaF-10GdF3-4P2O5(in mol%). XRD and TEM were used to investigate the microstructure of GdPO4glass-ceramics. Results show that GdPO4nanocrystals were homogeneously precipitated among oxyfluoride aluminosilicate glass matrix, and the mean size of GdPO4nanocrystals was about20～30nm. Meanwhile, excitation spectra, emission spectra and fluorescence decay decurves were measured, and proved that Eu3+and Tb3+ions had entered into GdPO4nanocrystals and there existed energy transfer from Tb3+to Eu3+. Excited by350nm light, pure white emission were achieved in Eu/Tb co-doped oxyfluoride aluminosilicate glasses and glass ceramics. Our researches show that Eu/Tb co-doped precursor glasses and GdPO4-based glass ceramics may be promising materials for lighting and luminescent applications.