Sythesis And Properties Of Metal Ions Co-doped Rare Earth Orthophosphate Phosphors

Ions co-doped orthophpsphate phosphors(Ln PO4:RE3+, Mn+( Ln=Y, La; RE=Eu3+, Tb3+; Mn+=Co2+, Cd2+, Mn2+, Li+, In3+, Mg2+)) were synthesized by polyacrylamide gel and hydrothermal techinques. The phase structures, crystal sizes, morphologies and luminescence properties of as-synthesized samples were characteized by X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), Scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FT-IR),(ICP-AES) and Fluorescence spectroscopy.A route of synthesising rare eath doped yttrium orthophsphate phosphors by hydrothermal techinque has established.The influence of the p H of the reaction system, the hydrothermal treatment temperature, and hydrothermal treatment time on the phase structures and luminescence properties of as-prepared samples were investigated. The XRD results indicate that the hydrothermal treatment temperature play the key role in the pahse structure. The YPO4·2H2O crystals with monoclinic structure can be obtained at 80 oC, and the YPO4 crystals with tetragonal structure can be prepared under 100 – 200 oC. The FL results reveal that the optimum synthesis condition of the synthetic of rare earth ions doped orthophsphate yttrium phosphors luminescent crystals by hydrothermal techinques could be summarized as follows: the p H of the reaction system is 2, the hydrothermal treatment temperature is 180 oC, and the hydrothermal treatment time is 18 h. The Co2+, Cd2+, Mn2+ co-doped YPO4:2%Eu3+ crystals with different co-doping contents were prepared via a hydrothermal route and a polyacrylamide gel process. The influence of doping contents and diffetent ions(Co2+, Cd2+, Mn2+) on the phase structures and luminescence properties of co-doped YPO4:2%Eu3+ phosphors samples synthesis were discussed. The results shown that the phase structures of the as-prepared a slight metal ions co-doped YPO4:2%Eu3+ samples were remain unchanged,but the diffraction intensity,grain size and cell volume of the as-prepared samples were changed. The samples obtianed by hydrothermal mehtod display higher degree of crystallinity than that of the samples prepared by polyacrylamide gel technique. The luminescent spectra results reveal that the doping contents of the metal ions play a key role in the luminescent intensity of the as-synthesized products, while has a less influence on the luminescence spectra constitutes of the as-prepared samples. Theoptimum co-doped contents for Co2+, Cd2+, Mn2+ were 0.1%, 0.1%, and 0.5%, respectively. The co-doped YPO4:2% Eu3+, x% Mn+(Mn+=Co2+, Cd2+, Mn2+)samples emit the characteristic Eu3+ orange-red light under UV light excitation. The co-doped YPO4:2% Eu3+, x% Mn+(Mn+=Co2+, Cd2+, Mn2+)samples exhibit stronger luminescent intensities than that of the YPO4:2% Eu3+ sample. The reason of luminescent intensity enhancement by co-doped Co2+, Cd2+, Mn2+ ions were been investigated.The influence of the pH of the reaction system, the hydrothermal treatment temperature, and hydrothermal treatment time on the phase structures and luminescence properties of the as-prepared rare earth ions doped lanthanum orthophsphate phosphors were investigated. The XRD results indicate that the La PO4 crystals with hexagonal structure can be obtained at 90 oC, and the La PO4 crystals with monoclinic structure can be prepared under 120 – 200 oC. The FL results reveal that the optimum synthesis conditions of the synthetic of rare earth ions doped lanthanum orthophsphate phosphors luminescent crystals by hydrothermal techinques could be summarized as follows: the p H of the reaction system is 2, the hydrothermal treatment temperature is 180 oC, and the hydrothermal treatment time is 12 h. The Mn2+, In3+, Li+ co-doped La PO4:2%Eu3+ crystals with different co-doping contents were prepared via a hydrothermal route and a polyacrylamide gel process. The influence of doping contents and diffetent ions(Mn2+, In3+, Li+) on the phase structures and luminescence properties of the co-doped La PO4:2%Eu3+ phosphors samples were discussed. The results shown that the phase structures of the as-prepared a slight metal ions(Mn2+, In3+, Li+) co-doped La PO4:2%Eu3+ samples were remain unchanged, while the phase structure of the as-prepared samples changed from monoclinic to hexagonal when the In3+ doping contents were above 3%, and some Li La(PO3)4 impurity phase appeared when the Li+ doping concents were no less than 1%. The luminescent spectra results reveal that the doping contents of the metal ions has a less influence on the luminescence spectra constitutes of the as-prepared samples, while play a key role in the luminescent intensities of the as-synthesized products. The optimum co-doped contents for Mn2+、In3+、Li+ were 1%, 1%, and 7%, respectively. The intensities of the La PO4:2% Eu3+ sample co-doped with 7% Li+ was 2.2 fold than that of the La PO4:2% Eu3+ phosphors. In addition, the luminescence efficiency of the as-synthesized samples co-doped with Mn2+(1%), In3+(1%), Li+(7%) were 10%, 6.4%, and 2.8% higher, respectively, than that of the La PO4:2% Eu3+ sample. The possible mechanism of luminescent efficiency enhancement by co-dopedMn2+, In3+, Li+ ions were been investigated.The Mg2+ and Tb3+ co-doped YPO4 crystals, Co2+ and Tb3+ co-doped La PO4 phosphors with different co-doping contents were prepared via a hydrothermal route. The influence of doping contents with diffetent ions(Mg2+, Co2+) on the phase structures and luminescence properties of the samples were discussed. The results shown that the phase structures of the as-prepared a slight metal ions Mg2+ co-doped YPO4: 2%Tb3+ samples were unchanged, and a tetragonal phase YPO4 crystals with xenotime structure can be obtained. The phase structures of the as-prepared a slight metal ions Co2+ co-doped La PO4: 2%Tb3+ samples were also unchanged and a monoclinic phase monazite structure La PO4 crystals can be obtained. The FL results reveal that excitation spectra and emission spectra of YPO4:Tb3+, Mg2+ and La PO4:Tb3+, Co2+ samples were all consisted of similar characteristic band of Tb3+. The YPO4:Tb3+, Mg2+ and La PO4:Tb3+, Co2+ samples emit the characteristic Tb3+ green light under UV light excitation. The doping contents of the Mg2+ and Co2+ ions play a key role in the luminescent intensities of the as-synthesized products. The intensities of the as-synthesized YPO4:Tb3+, Mg2+ and La PO4:Tb3+, Co2+ samples were increasedwhen the doping contents of Mg2+ and Co2+ were 0.3% and 0.2%, respectively.