Study On Luminescent Properties And Treatments Of The Phosphors Doped The Rare-Earthlons Under VUV-UV Exciting

The luminescent properties of the rare-earth ions has been studied for many years. There has been many important discovery. The study of the energy levels of the rare-earth ions has been developed from the low 4f levels to the high 4f levels and 4f5d state or the higher energy states. Some important discoveries of the luminescent properties of the rare-earth ions under high energy exciting, such as the high efficient quantum cutting of the rare-earth ions in the fluoride, but many basic study still need to be done by us. Presently, in order to improve the luminescent efficiency of the phosphors under high energy VUV exciting, the properties of the host absorption band and the 4f5d states and the charge transfer band has to be studied. The purpose of this paper is to research the spectroscopy characteristics and the luminescent mechanisms of the electronic transitions at 4f levels and 4f5d state of rare earths under VUV and short wavelength ultraviolet exciting, the energy transfer, the properties of the host absorption band and the charge transfer band of the rare earth ions, and the reasons that infect luminescence properties, and to find the methods of increasing the luminescent efficiency of the PDP and the mercury-free lamps materials. The results and progresses obtained are as follows:1.Study of the properties of the host absorption band of the rare-earth orthophosphate doped different rare earth ions has been done. The rare-earth orthophosphates doped Ce³⁺, Sm³⁺, Gd³⁺, Eu³⁺ or Tm³⁺ has been first prepared. The exciting spectrum show that the host absorption bands of the rare-earth orthophosphate doped different rare earth ions increase as the radius of the doped rare earth ions decrease. And the host absorption bands of the LaPO₄ and YPO₄ doped Ce³⁺ or Tm³⁺ increase as the radius of the cation of the host decrease. It can be concluded that the effect of the decrease of the radius of the doped rare earth ions or the cation of the host is the same. It all make the space between the doped ions and the anion of the host small, and this make the effect of the crystal field of the host on the doped ions stronger, and the energy transfer between the doped ions and the host will be increase.2.Study of the properties of the 4f5d states of the rare-earth orthophosphate doped different rare earth ions has been done. The electronic transitions at 4f5d state of rare earths in the VUV and UV area of the sample of LaPO₄ doped Sm³⁺, Dy³⁺ or Ce³⁺ has been first studied. It has been found that the electronic transitions at 4f5d state of rare earths move to the low energy level as the electronegative ability of the doped rare-earth ions decrease.3.The charge transfer band of the sample of LaPO₄ doped Tm³⁺, Sm³⁺ or Eu³⁺ has been first studied. The charge transfer band of the sample of LaPO₄ doped Tm³⁺, Sm³⁺ or Eu³⁺ stand at 183nm,193nm and 253nm.It can be found that the charge transfer band of the sample of LaPO₄ doped Tm³⁺,Sm³⁺ or Eu³⁺ move to low energy level while the electronegative ability of the doped rare-earth ions decrease.4.The energy transfer between Tm³⁺and Gd³⁺ ions in the sample of GdPO₄:Tm³⁺,Gd³⁺ has been first found. The mechanisms of this kind of energy transfer has been studied. The model according the study of the mechanisms of this energy transfer has been put forward. The energy transfer between Ce³⁺ and Tm³⁺ ions in the sample of LaPO₄: Ce³⁺,Tm³⁺ has also been first found. The mechanisms of this kind of energy transfer has also been.studied. The sample of LaPO₄: Ce³⁺, Eu²⁺ has been first prepared. The energy transfer between Ce³⁺ and Eu²⁺ ions in the sample of LaPO₄: Ce³⁺,Eu²⁺ has also been first found. The mechanisms of this kind of energy transfer has been studied. It is concluded that the energy transfer between the Eu²⁺ and Ce³⁺ ion in lanthanum phosphate is to be a process of resonance of dipole-dipole interaction.5.The attenuation of bright of the red phosphor, Y₂O₃.Eu, in the mixing process of the rare earth three band phosphors is first reported. The reason of the attenuation of bright of the red phosphor in the mixing process of the rare earth three band phosphors has been research. A method has been found which substantially reduces this kind of decrease of bright of the red phosphor. The method comprises forming a coating around individual particles of the red phosphor Y₂O₃:Eu. After the coating treatment, the attenuation of bright of the red phosphor in the mixing process of the three band phosphors is substantially reduced.