Synthesis And Luminescence Properties Of Rare-earth Doped In Phosphates Via Sotvothermal Method

Rare earth luminescence materials are widely used in our daily life. According tothe statistics, inventions relating to rare earth are up to one5of the new patentinventions. Because of its unique4f level transition character, rare earth are widelyresearched and applied. Due to the particular f-f, f-d level transition, rare earth isidentified as a great light treasure. As a way of being that rare earth elements in thenature, rare earth phosphate luminescence materials are wildly researched because ofits advantages, such as good physical and chemical stability, high luminous efficiencyin ultraviolet excitation. Nowadays, the researchs about rare earth phosphate aretrying to find new ways to prepare phosphor that costs less, luminous efficiencyhigher, and show color better than before. So it is meaningful that using nanotechnology to synthesize rare earth phosphate.In this paper, the structure and characteristics of luminescence of rare earthphosphate are introduced. Nano LnPO₄:RE(Ln=La,Ce,Y;RE=Eu³⁺,Tb³⁺) aresynthesized by solvothermal method, the samples are tested by XRD, TEM andfluorescence spectrometer. The of this paper focus on luminescence characteristicswhen Tb³⁺doped in LnPO₄:Tb³⁺（Ln=La,Ce,Y） and the relationship between opticalproperties of Eu³⁺and Tb³⁺and molar mass of phosphate radical. Main content can bedivided as follows:1. LaPO₄, CePO₄and YPO₄·0.8H₂O nano materials were fabricated bysolvothermal method. The samples were characterized by XRay Diffractomer andtransmission electron microscope. LaPO₄shape into nano granular, path in10nmaround; CePO₄shape into nano granular, path in2nm around; YPO₄·0.8H₂O shapeinto nano rods, path in11nm around. The grain size and crystallinity of LaPO₄、YPO₄·0.8H₂O get better as the increased of phosphate radical molar mass increased to2mmol.2. The luminescence properties of LaPO₄:Tb³⁺, CePO₄:Tb³⁺andYPO₄·0.8H₂O:Tb³⁺were analyzed in the third chapter. We discussed the changes ofLaPO₄:Tb³⁺and the luminescence properties of YPO₄·0.8H₂O:Tb³⁺when thephosphoric acid root molar mass changed. We find that the phosphate′s molar masschanged will lead to the color of LaPO₄:Tb³⁺changed，the color is green when themolar ratio was1:1between rare earth and phosphate, and color turn to blue when theratio was1:2. The luminescence properties of two YPO₄·0.8H₂O:Tb³⁺samples which synthesised at different phosphate′s molar mass, the excitation spectrum of the sample,when the molar ratio was1:1between rare earth ion and phosphate, only has4f-5dspin forbidden transition, the sample prepared in the molar ratio of1:2has4f-4ftransition and4f-5d spin allowed transition. The excitation of CePO₄:Tb³⁺4f-4ftransition and4f-5d spin forbidden transition.3. The luminescence characteristics of Eu³⁺, when it doped in LaPO₄, wereanalyzed. Optical transition strength parameters were calculated from emissionspectrum of LaPO₄:Eu³⁺based on J-O theory. We find that the luminous efficiency ofthe sample prepared at the ratio between rare earth ion and phosphate was1:1, thissample maybe can improve to be red phosphor powder stimulate nearly ultraviolet,and the sample prepared in a ratio of1:2is not so good.