Preparation And Photoluminescence Properties Of New Molydates Red Phosphor For White Light Emitting Diodes

This paper is based on previous studies to optimize process. The red phosphorssuch as SrMoO₄: Eu³⁺, M+（M=Li、Na、K）、CaMoO₄: Eu³⁺, M³⁺（M=Sm、Bi） andCaMoO₄: Eu³⁺, M³⁺, Li+（M=Sm、Bi） were synthesized through sol-gel method andco-precipitation method by doping with Eu³⁺, Eu³⁺/Gd³⁺, Eu³⁺/Bi³⁺and Eu³⁺/Sm³⁺,using alkali metal ions Li+、Na+、K+as charge compesation irons. The surfacemorphology, phase structure and luminescent properties of the alloys werecharacterized by XRD, SEM, and ZWL-900LED Spectral Analysis System. At thesame time, the author personally operated the experiment, analysed the experimentaldata by a large number of documents under the guidance of the tutor. The conclusion isthat:First, the red phosphors the series molybdates such as MMoO₄:Eu³⁺（M=Ca、Sr、Ba） were prepared by sol-gel method. The alkali metal ions Li+、Na+、K+as chargecompesation irons were imported to balance the charge between Eu³⁺and M2+. Theresults show that the phosphors belong to tetragonal schelite-type structure. ForSrMoO₄:Eu³⁺,M+（M=Li、Na、K） samples, Li+ion can improve the intensity of thephosphors obviously. For MMoO₄:Eu³⁺,Li+（M=Ca、Sr、Ba）, the luminescence intensityof CaMoO₄:Eu³⁺,Li+phosphor is highest. The CaMoO₄is more suitable for matrixmaterials. The intensity at the ultraviolet light of395nm of CaMoO₄:Eu³⁺, Li+phosphor is about2.1times of commercial Y2O2S:Eu³⁺phosphor, which suggestedCaMoO₄:Eu³⁺,Li+phosphor is more suitable for effective excitation of the ultravioletlight.Secondly, the SrMoO₄phosphor was prepared by co-precipitation method dopingwith Eu³⁺, Eu³⁺/Gd³⁺. The optimum preparation process was studied. The results showthat the main diffraction peaks of all the samples corresponded to the standard cardJCPDS08-0482, belonging to tetragonal structure. Meanwhile, the optimum processconditions to prepare phosphor should choose the burning temperature of800℃.Eu³⁺-doped quantity x is0.25. Gd³⁺-doped quantity x is0.35. The potential ofhydrogen is7. The precipitant-doped optimum quantity x is2.5mol. The graph to begiven blow is under the best technological conditions result. The intensity of SrMoO₄:Eu³⁺, Gd³⁺and SrMoO₄:Eu Eu³⁺,Gd³⁺,Li+phosphors is about1.8and2.5timesof commercial Y2O2S: Eu³⁺phosphor, respectively.Finally，the CaMoO₄:Eu³⁺and CaMoO₄:Eu³⁺,M³⁺,Li+（M=Sm、Bi） phosphors wereprepared by co-precipitation method. The test results show the phosphors belong to atetragonal single phase. The space group is I41/a （88）. Simultaneously, Sm³⁺-dopedquantity x is0.04. Bi³⁺-doped quantity x is0.01. The intensity at the ultraviolet light of395nm of CaMoO₄:Eu³⁺, Sm³⁺, Li+and CaMoO₄:Eu³⁺, Bi³⁺, Li+are about2.8and2.2times of commercial Y2O2S:Eu³⁺phosphor, respectively.