Synthesis And Properties Of Rare Earth Doped RE（PO₃）₃（RE=Y,La,Gd） Luminescent Materials

The rare earth ions doped and alkaline earth metal ions-rare earth ions co-doped RE（PO₃）₃（RE=Y,La,Gd）luminescent materials were prepared by a co-precipitation method.The phase structure,sizes,morphologies and optical properties of the as-synthesized samples were characterized by X ray diffraction（XRD）,Fluorescence spectroscopy（FL）,Fourier transform infrared spectroscopy（FT-IR）and Scanning electron microscopy（SEM）.The influence of the mole ratio of RE（RE=Y+Eu）to P（n（Y+Eu）/n（P））,the calcination temperature,the calcination time and the pH of the reaction system on the phase structure and optical properties of the as-prepared Y（PO₃）₃:Eu³⁺luminescent materials were investigated.The results reveal that those synthesis conditions play the key role in the phase structure and optial properties of the as-synthesized samples.The optimum synthesis conditions for the synthesis of Y（PO₃）₃:Eu³⁺luminescent materials by co-precipitation method could be summarized as follows:the mole ratio of RE（RE=Y+Eu）to P（n（Y+Eu）/n（P））is 1:3,the calcination temperature is 850°C,the calcination time is 24 h and the the pH of the reaction system is 2.The high-performance Y（PO₃）₃:Eu³⁺crystal with monoclinic structure can be synthesized under the optimum synthesis conditions.A series of Eu³⁺and Tb³⁺doped Y（PO₃）₃ luminescent materials with different doping concentrations were synthesized by a co-precipitation method.The phase structures and optical properties of the as-prepared materials were investigated.The results show that the Eu³⁺doped in the Y（PO₃）₃ crystals has less effect on the phase structure of the as-syntheszied samples under the experimental range.The luminescence centers Eu³⁺doped in Y（PO₃）₃ matrix being in a higher symmetry position.The Eu³⁺doped Y（PO₃）₃ sample with the doping amount is 0.20 displays the strongest luminescent intensity compared to the other doping content.The serie of Y_1-x（PO₃）₃:x Tb³⁺（x=0.10¹.00）samples with diffenent Tb³⁺doping amount exhibit quite similar XRD diffraction patterns.All the Tb³⁺doped Y_1-x（PO₃）₃:x Tb³⁺（x=0.10¹.00）samples exhibit the characteristic green emission of Tb³⁺ions.No concentration quenching phenomenon can be observed in the as-prepared Y_1-x（PO₃）₃:x Tb³⁺（x=0.10¹.00）samples.A series of Sm³⁺,Dy³⁺,Ce³⁺doped RE（PO₃）₃（RE=Y,La,Gd）luminescent materials with different doping contents were prepared by a co-precipitation method.The phase structures and optical properties of the as-synthesized materials were studied.The XRD results show that the as-prepared Sm³⁺,Dy³⁺,Ce³⁺doped Y（PO₃）₃materials are pure phase Y（PO₃）₃ crystals which are in accordance with the standared diffraction pattern of Y（PO₃）₃（JCPDS No.42-0501）.And the as-synthesized Gd_0.98（PO₃）₃:0.02Sm³⁺sample is single phase of Gd（PO₃）₃ crystal.However,the structure of the as-prepared La_0.99（PO₃）₃:0.01Sm³⁺sample is mixed phases of La（PO₃）₃ and LaP₃O₉,and the La（PO₃）₃ pahse is the main pahse in the mixed pahses.In the experimental range,Sm³⁺,Dy³⁺,Ce³⁺doped Y（PO₃）₃ luminescent materials exhibite the maximum luminescence intensity when the doping amounts of Sm³⁺,Dy³⁺and Ce³⁺are 0.03,0.07 and 0.015,respectively.The Sm³⁺,Dy³⁺and Ce³⁺doped La（PO₃）₃luminescent materials display the strongest luminescence intensity when the doping amounts of Sm³⁺,Dy³⁺and Ce³⁺are 0.03,0.05 and 0.02,respectively.Meanwhile,when the Sm³⁺,Dy³⁺and Ce³⁺doping amounts are 0.01,0.03 and 0.03,respectively,the obtained Sm³⁺,Dy³⁺,Ce³⁺doped Gd（PO₃）₃ crystals show the highest luminescence intensity.The characteristic excitation bands and emission bands of Sm³⁺,Dy³⁺and Ce³⁺ions can be observed in the as-prepared Sm³⁺,Dy³⁺,and Ce³⁺doped RE（PO₃）₃（RE=Y,La,Gd）luminescent materials.However,the compositions and relative intensities of the excitation spectra and emission spectra for Sm³⁺,Dy³⁺and Ce³⁺doped RE（PO₃）₃（RE=Y,La,Gd）crystals are different due to the different RE（PO₃）₃（RE=Y,La,Gd）substrates.A series of M(M=Mg²⁺,Ca²⁺,Sr²⁺,Ba²⁺)co-doped Y（PO₃）₃:Tb³⁺samples were synthesized by a co-precipitation method.And the phase structures and optical properties of the as-syntheiszed samples were explored.The results show that the alkaline earth metal ions co-doped in the Y（PO₃）₃:Tb³⁺crystlas have not significantly inflence on the phase structure for the as-prepared samples in the experimental range.The photoluminescence spectra results reveal that the alkaline earth metal ions M(M=Mg²⁺,Ca²⁺,Sr²⁺,Ba²⁺)co-doped Y（PO₃）₃:Tb³⁺samples with a suitable co-doping luminescence properties.The optimum co-doping amount for Mg²⁺,Ca²⁺,Sr²⁺and Ba²⁺ions is 0.10,0.15,0.10 and 0.06,respectively.The intensity of the strongest emission peak of the M(M=Mg²⁺,Ca²⁺,Sr²⁺,Ba²⁺)co-doped Y（PO₃）₃:Tb³⁺samples with the optimum co-doping content is about 127%,274%,230%and 60%higher than that of Y（PO₃）₃:Tb³⁺sample,respectively.