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Study On Preparation And Luminescent Properties Of Sm3+ Doped MceO3(M=Sr,Ba) Based And CeO2Based Luminescent Materials

Posted on:2014-05-28Degree:MasterType:Thesis
Country:ChinaCandidate:L WeiFull Text:PDF
GTID:2251330392465132Subject:Analytical Chemistry
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Rare earth oxide has been widely used as the matrix of rare earthlumi nescent materials for its excellent physical and chemicalproperties. In order to prepare the red phosphor that can be excitedby the UV-near UV, in this paper, use Sm3+as an activator, useSrCeO3, CeO2and BaCeO3as a substrate, respectively. Thelumi nescence properties and rear earth ions doping research werecarried out by di fferent method.The red phosphor of SrCeO3: Sm3+was synthesized by sol-gelmethod. The samp le belongs to orthorhombic crystal syste m whic hwas ellipsoid-liked, and the size of particles was about200nm. Theemission spectrum excited by408nm, showed strong red e missionpeak at601nm that due to4G5/2→6H7/2of Sm3+. The doping amountof Sm3+will affe ct the lumi nous i ntensity of sa mples, and theopti mum amount of Sm3+was about3mol%, otherwise the electricdipole and electric dipole action between Sm3+will causeconcentration quenching. Co-doping Li+, Na+, K+as chargecompensa tion, and the lumi nescence intensity of SrCeO3: Sm3+increased the most when co-doping Li+. The opti mum amount ofcharge compensators Li+, Na+, K+were5mol%,2mol%and0.8mol%, respectively. Use H3B O3as a flux and it al so can improve thelumi nescence intensity of samples, and its optimum a mount was0.5mol%, then the morphology of sa mples was better.The lumi nescent ma terials CeO2:Sm3+was obtained with Sm3+asthe activator and KNO3as t he molten salt. The sa mple belongs tocubi c fluorite structure, and the morphology of particle was nearlyspherical, the size of particles was about1μ m. T h e e x ci t at i o nspectrum of CeO2: Sm3+has two absorption band located at250~300and320~400nm, each belongs to the charge transfer fromO2-→Sm3+and fr om O2-→Ce4+. Under UV excitation with awavelength358nm, three shape peaks appeared which were split withthe action of the crystal field. The strongest peaks were located at 572and615nm, attributed to4G5/26H5/2and4G5/2→6H7/2of Sm3+,respectively. The opti mum a mount of Sm3+was a bout0.6mol%, andthe ion exchange between Sm3+was the mechanism of concentrationquenching.The BaCeO3: Sm3+sal mon pink fluorescent material wasprepared by sol-gel method. The structure of Ba CeO3: Sm3+was cubiccrystal syste m, and the space group was Fm3m.The e missionspectrum excited by353nm, showed three sharp peaks which locatedat572,615and655nm, all of the m we re attributed to the transition4G5/2→6HJ(J=5/2,7/2,9/2) of Sm3+. The lumi nescence intensityfirstly increased, and then decreased with the increase of dopinga mo u n t o f Sm3+. The opti mum a mount of Sm3+was0.4mol%, and themechanism of concentration quenching was the action of ionexchange between Sm3+. The l u mi nescence intensity of Ba CeO3: Sm3+increased after co-doping Li+, Na+and K+as charge compensation.The opti mum a mount of charge compensators Li+was12mol%, andthen the lumi nescence intensity of s ample rose4.42times. Theopti mum amount of Na+and K+were8mol%and4mo l%,respectively. And the intensity of each sample was3.03and2.38ti mes than the sample that didn’t co-doping Na+and K+.
Keywords/Search Tags:perovskite, cerium oxide, molten-salt method, phosphor, Energy transfer
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