Synthesis And Properties Of Several Rare-Earth Phosphors

In this thesis,rare-earth luminescent materials based on Ca3Al2O6:Eu/Tb/Sm?La4SrO7:Eu/Sm/Tb?CaWO4:Eu,Tb were successfully synthesized by Pechini sol-gel method.And Na2Ca3A12F14:Ce/Tb/Eu were successfully synthesized by Hydrothermal method.The crystal structure,morphology and luminescent properties were investigated using X-rays diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR)were used to characgterized the structures of the phosphors;scanning electronmicroscopy(SEM)was utilized to characterized the morphology;photoluminescence spectra(PL)were used to chareacterized the luminescent properties.The optimum annealing temperatures of Ca3Al2O6:Eu/Tb/Sm was 900 ?,much lower than the traditional solid state method of 1350 ?.The average grain size of as prepared phsophors is 1500 nm with an even size distribution.Exciation spectrum of Ca3A12O6:Eu is dominated by the 223 nm band originated from Eu-O charge transfer transition.Ca3Al2O6:Eu emission shows characterstic emission of Eu3+,dominated by electric dipole transition of 5D0-7F2 at 612 nm.The optimum doping concentration of Eu3+ is 5mol%.Exciation spectrum of Ca3Al2O6:Tb is dominated by the 223 nm band originated from 4fg-4f75d1 transition.Emission spectrum originated from 5D3,4-7FJ,,domimated by5D3-7F6 at 378 nm and 5D4-7F5 at 542nm.Optimum doping concentration of Tb3+ is 1 mol%.Ca3Al2O6:Sm is dominated by the 222 nm band originated from 6H5/2?4H7/2 transition.Emission spectrum is domimated by 4G5/2-6H7 at 605 nm.Optimum doping concentration of Sm3+ is 4 mol%.The optimum annealing temperatures of La4SrO7:Eu/Sm/Tb was 1150 ?.Exciation spectrum of La4SrO7:Eu is dominated by the 223 nm band originated from Eu-0 charge transfer transition.La4SrO7:Eu emission shows characterstic emission of Eu3+,dominated by electric dipole transition of 5D0-7F2 at 622 nm.The optimum doping concentration of Eu3+ is 5mol%.Exciation spectrum of La4SrO7:Sm is dominated by the 222 nm band originated from 6H5/2?4H7/2 transition.Emission spectrum of La4SrO7:Sm is domimated by 4G5/2?6H7/2 at 608 nm.Optimum doping concentration of Sm3+ is 2 mol%.Exciation spectrum of La4SrO7:Tb is dominated by the 223 nm band originated from 7F?6D transition.Emission spectrum of La4SrO7:Tb is domimated by 5D4?7F5 at 541 nm.Optimum doping concentration of Tb3+ is 4 mol%.The optimum annealing temperatures of CaWO4:Eu,Tb was 1100 ?.Exciation spectrum of CaWO4:Eu,Tb is dominated by the 256 nm band originated from W-O charge transfer transition.Emission spectrum of CaWO4:Eu,Tb is domimated by 5D0-7F2 at 615 nm.And Eu3+and Tb3+ have common characteristic emission peaks at 615 nm.In addition,Na2Ca3A12F14:Ce/Tb/Eu phosphors were synthesized by hydrothermal method.Na2Ca3Al2F14:Ce/Tb/Eu were synthesized at 200 ?.Exciation spectrum of Na2Ca3A12Fi4:Ce is dominated by the 253 nm band originated from 4f1-5d1 transition.Emission spectrum of La4SrO7:Sm is domimated by 5d1-4f1 at 365 nm.Optimum doping concentration of Sm3+ is 4 mol%.Exciation spectrum of La4SrO7:Tb is dominated by the 248 nm band originated from 4f8-4f75d1 transition.Emission spectrum of La4SrO7:Sm is domimated by 5D4?7F5 at 540 nm.Optimum doping concentration of Tb3+ is 4 mol%.Exciation spectrum of La4SrO7:Eu is dominated by the 258 nm band originated from 2p-4f transition.Emission spectrum of La4SrO7:Sm is domimated by 5D0-7Fj at 585 nm.Optimum doping concentration of Eu3+ is 3 mol%.