Preparation And Luminescent Properties Of Red Phosphors With Eu³⁺ Doping

Rare earth doping phosphors have important applications in new illumination source,display and imaging,and biological medicine due to their excellent properties,and have attracted more and more attentions recently.The red luminescent material Gd2O3:Er3+ with special morphology was successfully fabricated by hydrothermal synthesis and calcination treatment.The effects of hydrothermal temperature and time,concentration of Gd3+ in hydrothermal solution,urea precipitant and calcination temperature on the morphology and luminescent properties of Gd2O3:Eu3+phosphors were investigated.The appropriate conditions of forming uniform and dense Gd2O3:Eu3+ sphere with nano-hole were obtained,and the mechanism was discussed.The effects of surfactant CTAB on the morphology and luminescent properties of Gd2O3:Eu3+ phosphors synthesized by hydrothermal method were also investigated and the results show that CTAB has little effect on the morphology.The main excitation band is around 266nm,which is attributed to the charge-transfer transition from the 2p orbital of O2-to the 4f orbital of Eu3.Upon 266nm excitation,the dominant red emission?613nm?was observed which has been assigned to 5D0-7F2 transition of Eu3+.The red-emitting phosphors Gd2O3:Eu3+ with special morphology may find potential applications in bioseparation,drug targeting and diagnostic analysis.A series of LiGd_1-xEu_x?MoO₄?₂ red-emitting phosphors were synthesized by conventional solid-state reaction.It was found that the appropriate calcination temperature and holding time is 900? and 5h.Theeffects of Eu3+ doping concentration on the luminescent properties of LiGd1-xEux?Mo04?2 were systematically studied,and the luminescent properties of low concentration Eu3+-doping LiGd_1-xEu_x?MoO₄?₂ were investigated in detail for the first time in this system.The emission intensity of LiGd_1-xEu_x?MoO₄?₂ enhances with the increase of Eu3+ doping concentration,and no concentration quenching was observed with x=0 to 1.The XRD characterization indicate that LiGd?Mo04?2 and LiEu?Mo04?2 have the same structure,but substitution Gd3+ with Eu3+ will change the symmetry of the host crystal field in LiGd?Mo04?2 and then influence its luminescent properties.The luminescent properties of Eu3+-Bi3+ co-doped LiGd?Mo04?2 red phosphors were also investigated.A series of LiGd0.93Eu0.07?MoO4?2-x?WO4?x red-emitting phosphors were synthesized via conventional solid-state reaction method.It was found that the appropriate calcination temperature and holding time is 900? and 3h.The crystal structure and luminescent properties of LiGd0.93Eu0.07?MoO4?2-x?WO4?x were studied.The XRD characterization indicates that LiGd0.93Eu0.07?MoO4?2-x?WO4?x has a tetragonal scheelite structure.The variation of the emission intensity with MoO₄^2-and WO₄^2-concentration in LiGd0.93Eu0.07?MoO4?2-x?WO4?x was discussed,and when x=0.9,the emission intensity reaches the maximum value.The LiGd_1-xEu_x?MoO₄?₂ and LiGd0.93Eu0 07?Moo4?2-X?W04?X red-emitting phosphors show strong excitation band around 395nm and 466nm,which are well matched with the ultraviolet and blue light LED chips currently in use.Upon excitation with 395nm and/or 466nm,the phosphors show strong red emission lines at 617nm which is ascribed to the forced electric dipole transition of 5D0-7F2.The prepared samples are potential red phosphors for White LEDs application.