Preparation And Performance Of Up-conversion Luminescence Material Compound Of Tio <sub> 2 </ Sub>

The composites Y2O3:Er3+ and NaYF4: Er3+ were prepared using coprecipitation and hydrothermal process, respectively. The composites Y2O3:Er3+/TiO2 and NaYF4:Er3+/TiO2 were prepared by sol-gel techniques. There are four same green-emitting fluorescents when the sample is excited by the three different wavelengths, which is probable to improving the fluorescence efficiency. The composites Y2O3:Er3+/TiO2 and NaYF4: Er3+/TiO2 both have up-conversion property. The composites absorb photons of long wavelength and then emit photons of short wavelength which make TiO2 better photocatalytic performance.Microstructural analysis shows Y2O3:Er3+ has the cubic phase, whose particle diameter is 20～30 nm. Y2O3:Er3+ has five ultraviolet visible absorption peaks:365,377,489,521 and 652nm which is characteristic peaks of Er3+. There are four green-emitting fluorescents which are 522,537,550 and 562nm when the sample is excited by 365,377 and 521nm. When the Ag+ is doped with the sample the fluorescents become stronger while the biggest multiple is 87.5%. The optimum doping content of Er2O3 and annealed temperature is 1% and 1200℃, respectively.XRD and SEM images analysis show NaYF4:Er3+ is hexagonal microparticles whose appearance is pentahedron. NaYF4:Er3+ show several emission peaks with their maximum at (211,237,251nm) under the excitation of 388nm, at (395,411nm) under the excitation of 500nm, at 467nm and (481,492,508nm) under the excitation of 570nm, respectively.The composites Y2O3:Er3+/TiO2 and NaYF4:Er3+/TiO2 has the same up-conversion luminescence propertry, but their appearances are different from each other. The Y2O3:Er3+/ TiO2 composite whose particle diameter is 10 nm has two compositions:anatase TiO2 and cubic Y2O3:Er3+. The NaYF4:Er3+/TiO2 composite has three compositions:anatase TiO2, hexagonal phase NaYF4:Er3+ and YO1.335, whose morphology is mainly viereck and a few round microparticles. The specific surface area indicates the structure of both two composites has altered a little. The two composites both has three improved ultraviolet visible absorption peaks:489,521 and 652nm which is characteristic peaks of Er3+. From the calculation and analysis of excitation wavelength, we speculated the luminescence under the excitation of 388 and 500nm can be belonged to Energy transfer up-conversion; The emission peaks 467nm and (481,492,508nm) under the excitation of 570nm can be belonged to Ground slate absorption, GSA/Excited state absorption, ESA or Energy transfer up-conversion.