The Study Of Preparation And Properties Of Rare Earth Ion Doped Borate/Phosphate Luminescent Materials

As a new generation of luminescent materials,rare earth doped luminescent materials have been widely used in display lighting,biomedicine,photoelectric conversion,environmental catalysis and other fields,which is currently the key research objects in the field of luminescence.The performance of rare earth luminescent doped materials is not only related to the type,content and valence of doped ions,but also largely depends on the crystal environment provided by the host material and the energy transfer between doped RE ions.Therefore,the design of new matrix materials and doped rare earth ions is essential for exploring novel and efficient rare earth luminescent materials.This study selects two kinds of host material,phosphate Ca9La(PO4)7 and borophosphate KBaBP2O8,as the research objects.The Ce3+/Tb3+/Mn2+doped Ca9La(PO4)7 and Ce3+/Tb3+ doped KBaBP2O8 materials were designed and synthesized.By a series of characterization and analysis methods,the crystalline phase,microscopic morphology,luminescence characteristics,emission color,practicability and luminescence mechanism of these phosphors have been studied in detail.The research contents and results are as follows:The crystal structure of Ce3+and Tb3+single-doped Ca9La(PO4)7 phosphor samples were determined by X-ray powder diffraction,and they were all single pure phases.Then,the crystal structure was analyzed with the Rietveld method.It belongs to the space group R3c(161)of the cubic system and shows rhombic hexahedral structure.Under U V excitation,Ca9La(PO4)7:Ce3+and Ca9La(PO4)7:Tb3+exhibited blue-violet and green light emission dominated by the characteristic transitions of Ce3+and Tb3+,respectively.The concentration-dependent luminescence characteristics were investigated,respectively.Meanwhile,the concentration quenching point and mechanisms of Ca9La(PO4)7:Ce3+ has been determined to be 0.30 and dipole-dipole electrical multi-level interaction,respectively.PL spectrum and fluorescence decay curve have evidenced the efficient energy transfers from Ce3+to Tb3+and from Ce3+to Mn2+in the Ce3+,Tb3+ and Ce3+,Mn2+ double-doped Ca9La(PO4)7 phosphors.And the corresponding energy transfer efficiency reaches 41.8%and 54.1%,respectively.The energy transfer process of Ce3+→Tb3+ and Ce3+→Mn2+ can be deduced to the resonant type via dipole-dipole and dipole-quadrupole interaction mechanism,respectively.Based on the energy transfer process,multi-color emission with a wide color gamut of blue violet-green-red including white light can be achieved by adjusting the doping concentration of Ce3+,Tb3+and Mn2+ ions.In addition,Ca9La(PO4)7:0.15Ce3+,0.10Tb3+,0.04Mn2+can achieve single-component white light emission,which owns CIE of(0.3245,0.3327),CCT of 5878K,the internal and external quantum efficiencies of 84.51%and 69.32%.The thermal stability still maintains 98.5%at 150℃ of that at room temperature.The results show that the phosphor has potential application value in the field of white light LED and solid-state lighting.A series of Ce3+and Tb3+-doped phosphor materials based on KBaBP2O8 were successfully prepared by the high-temperature solid-phase method,and the phase analysis showed that they were all in a single pure phase.The space group of the KBaBP2O8 crystal structure belongs to the tetragonal crystal system I42d,with a three-dimensional structure of diamond-like carbon topology,and K+|Ba2+are disordered co-occupancy.By analyzing the UV luminescence characteristics of KBaBP2O8:Ce3+,it is found that the KBaBP2O8 matrix has a strong crystal field effect on Ce3+,and there is only one Ba2+position in the crystal structure of KBaBP2O8.The concentration quenching is caused by dipole-dipole electrical multi-level interaction.There is an effective energy transfer between Ce3+and Tb3+in the Ce3+,Tb3+co-doped KBaBP2O8 phosphor.By changing the doping content of Tb3+,a larger range of green emission color can be achieved.Among them,the green-emitting KBaBP2O8:0.01Ce3+,0.06Tb3+phosphor has shown abnormal thermal quenching due to the matrix lattice defects.The emission intensity reaches 116.2%at 150℃ of that at room temperature.The results show that this phosphor have the potential application in high power LED devices.