Preparation Of Eu(Ⅲ) Doped Luminescent Materials And Effect Of Sensitizer On Spectral Characteristics

In this thesis,a series of Sm³⁺,Pb²⁺,Bi³⁺,Eu³⁺-codoped luminescent materials were prepared and their properties were studied.The main research work is as follows:（1）A new high thermal qualitative phosphor Li₃Ba₂La₃（WO₄）₈:Sm³⁺/Eu³⁺was prepared by high temperature solid state reaction.Upon excitation of the near-ultraviolet（UV）light（404 nm）,it shows the characteristic transitions of both Sm³⁺and Eu³⁺,due to happening of energy transfer from Sm³⁺to Eu³⁺.The intensity of Sm³⁺decreases along with the improving Eu³⁺concentration,whereas the Eu³⁺luminescence gets promoted.For Li₃Ba₂La_2.42Sm_0.08Eu_0.5（WO₄）₈,the internal quantum yield reaches up to53%.Moreover,co-doping Sm³⁺/Eu³⁺into Li₃Ba₂La₃（WO₄）₈possesses better fluorescence thermostability than sole doping Eu³⁺,about two times.The total PL integral intensity at 450 K of Li₃Ba₂La_2.87Sm_0.08Eu_0.05（WO₄）₈remains 83%of that at 300K,ensuring its applications in high power LED lamp.（2）YBa Zn₃Ga O₇:Bi³⁺/Eu³⁺were prepared by high-temperature solid-state reaction method,and their PL,PC and LPL properties were studied.Under the excitation of 341nm,YBa Zn₃Ga O₇:x Bi³⁺generated a broad emitting band centered at 564 nm,due to the³P₁→¹S₀transition of Bi³⁺ions.The optimized Bi³⁺concentration is x=0.003.For co-doped phosphors YBa Zn₃Ga O₇:0.003Bi³⁺/y Eu³⁺,they can realize multi-color emissions from green,through yellow to orange with the increasing of Eu³⁺concentration due to the energy transfer from Bi³⁺to Eu³⁺.Because of the flexible and easy to defects structure of YBa Zn₃Ga O₇host,there are oxygen vacancies（:F-like color center）in the YBa Zn₃Ga O₇host,forming a certain number of color centers around CB with shallow or deep energy levels.These results suggest that phosphors YBa Zn₃Ga O₇:x Bi³⁺/y Eu³⁺containing intrinsic defects could generate not only PL but also PC and LPL properties.Moreover,we put forward that these results can be generalized to other host materials with the flexible and easy to defects structure,to fabricate multi-functional materials.（3）Cs₂Ba₃（P₂O₇）₂:Pb²⁺/Eu³⁺phosphors were prepared by high-temperature solid-state reaction method.Under the excitation of 261 nm,the internal quantum yield of Cs₂Ba_2.88Pb_0.12（P₂O₇）₂phosphor reaches up to 35%.With the increasing of Eu³⁺concentration,the energy transfer from Pb²⁺to Eu³⁺is enhanced to generate multicolor emissions,from blue,through green to red.In addition,due to the different thermal quenching efficiency of Pb²⁺and Eu³⁺,the optical temperature sensoring properties for sample Cs₂Ba_2.73Pb_0.12Eu_0.15（P₂O₇）₂phosphor were evaluated.The maximum S_aand S_rvalues are 0.0162 K^-1and 0.965%K^-1,respectively.The results show that Cs₂Ba_{3（0.96-y）}Pb_0.12Eu_3y（P₂O₇）₂phosphor are a promising optical temperature sensor.