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Abstract: A new Er3+ doped oxyfluoride borosilicate glass ceramics was developed by controlling crystallization of the quenched glass. The hexagonal NaGdF4 nanocrystals were precipitated in the glass matrix, which was confirmed by the X-ray diffraction and TEM results. Notable enhancement of upconversion emission was observed in the Er3+ doped glass ceramics and attributed to the enrichment of Er3+ into NaGdF4 nanocrystals. With the increasing of Er3+ content, the upconversion emission density ration from green to red light greatly changed in the glass ceramics. This material may be used as a potential material for the silicon solar cells. [Copyright &y& Elsevier]

Abstract: Transparent oxyfluoride borosilicate glass ceramic containing cubic NaYF4 nanocrystals were successfully fabricated. The cubic NaYF4 nanocrystals with average size of 30nm were precipitated in the glass matrix, which was confirmed by the X-ray diffraction and TEM results. In comparison with the as-made glass, significant enhancement of upconversion luminescence is observed in the Er3+/Yb3+ codoped transparent glass ceramic, which may be due to the variation of coordination environment of Er3+ and Yb3+ ions after crystallization. The high transparency, intense upconversion luminescence and the simple, low-cost fabrication process make this material exhibiting potential applications in the fields of amorphous silicon solar cells. [Copyright &y& Elsevier]

Abstract: Ce3+ doped La4Ca(SiO4)3O phosphors with silicate oxyapatite structure were synthesized by the sol-gel process. The X-ray diffraction (XRD) patterns showed that a pure phase was formed when sintering temperature was higher than 1300°C. The optical properties of La4Ca(SiO4)3O:Ce3+ phosphors with varying sintering temperature and concentration were investigated by examining their excitation and emission spectroscopy. The phosphors exhibited a broad emission band centered at 550nm which could be attributed to the 5d-4f transition of Ce3+ and a stronger excitation peak around 467nm as well as several shoulder bands, nicely matching with the widely applied blue LED chips. Higher emission intensity was observed when firing temperature above 1300°C, due to increasing crystallinity of the powders. When Ce3+ concentration was equal to 5 at%, the sample exhibited the optimum excitation and emission efficiency. The results indicate that La4Ca(SiO4)3O:Ce3+ is a promising candidate in the application of blue chip excited white light emitting diodes (LEDs). [Copyright &y& Elsevier]

Abstract: Y6Si3O9N4:Ce3+ phosphor was prepared by a solid-state reaction in reductive atmosphere. X-ray powder diffraction (XRD) analysis confirmed the formation of Y6Si3O9N4:Ce3+. Scanning electron microscopy (SEM) observation indicated that the microstructure of the phosphor consisted of irregular fine grains with an average size of about 5μm. Photoluminescence (PL) measurements showed that the phosphor can be efficiently excited by near ultraviolet (UV) or blue light excitation, and exhibited bright green emission peaked at about 525nm. Compared with Ce3+-doped Y4Si2O7N2 phosphors, Ce3+-doped Y6Si3O9N4 phosphors showed longer wavelengths of both excitation and emission. The Y6Si3O9N4:Ce3+ is a potential green-emitting phosphor for white LEDs. [Copyright &y& Elsevier]