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Microwave Synthesis And Photoluminescent Properties Of Sr2CeO4,Sr2CeO4: Ln(Eu, Sm, Er, Ho, Tm) And Sr2CeO4: Eu, Gd

Posted on:2007-02-10Degree:MasterType:Thesis
Country:ChinaCandidate:H G KangFull Text:PDF
GTID:2121360182499609Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Research on the luminescent materials has entered a new stage since rare earth fluorescence powder for lights became the commercialization. Rare earth luminescent materials have now become the research focus of luminescent materials due to much excellent performance and a wide range of applications. The emergence of new synthetic methods provided new opportunities for improving the performance of luminescent materials. Microwave radiation method has characteristics such as rapid , efficient and being heated evenly and can bring the remarkable improvement to luminescent materials, which has attracted much attention since the past decade.Danielson et al. discovered new blue luminescent materials, Sr2CeO4, by using combinatorial chemistry technique in 1998. It can be used as the host material besides giving out light itself. In this article, Sr2CeO4, Sr2CeO4: Ln (Ln=Eu, Sm, Er, Ho, Tm) and Sr2CeO4: Eu, Gd phosphors are synthesized by microwave radiation method. The main contents are as follows:1. The research progress on the synthetic methods of Sr2CeO4 phosphor is summarized for the first time.2. It was once reported that Sr2CeO4 phosphor was synthesized by microwave radiation method. Here some improvements are made on it. The influence of microwave radiation power and heating time is discussed and the optimum condition to achieve superior Sr2CeO4 phosphor is confirmed. The structure , morphology and luminescent properties of the samples are characterized.3. Sr2CeO4: Ln(Ln=Eu, Sm) phosphors are synthesized by microwave radiation method for the first time. The results show that the energy transfer takes place between Ce4+ ion and Ln3+ ion energy levels. Ln3+ ion concentration in the host Sr2CeO4 phosphor has an effect on light emitting properties of Sr2CeO4: Ln phosphor. For values of Eu3+ ion concentration in the range 0.5% —>15%, the compound Sr2CeO4: Eu3+ gives the emission light from blue-white to red-white , further to red;For values of Sm3+ ion concentration in the range 1% -10%, the compound Sr2CeO4. Sm3+ gives the emission light from blue-white to red.4. Sr2CeO4: Ln(Ln=Er, Ho, Tm) phosphors are synthesized by microwave radiation method for the first time. The energy transfer from MLCT(Ce4+-O2-) to Ln3+ and up-conversion luminescence of Ln3+ ion are observed. When the Er3+ ion concentration is 4%, Sr2CeO4: Er3+ phosphor has the best effect of up-conversion luminescence. When the Ho3+ ion concentration is 1%, Sr2CeO4 Ho3+phosphor has the best effect of up-conversion luminescence. When the Tm3+ ion concentration is 1%, Sr2CeO4: Tm3+ phosphor has the best effect of up-conversion luminescence.5. Gd3+ ion is a fine activator and sensitizer. S^CeC^: Eu, Gd phosphors are synthesized by microwave radiation method for the first time. Gd3+ ion plays different roles on the luminescence of Sr2Ce04: Eu phosphors. Gd3+ ion acts as a quencher when the concentration of Eu3+ ion is as low as 1%. However, when the concentration of Eu3+ ion reaches 8%, Gd3+ ion acts as a sensitizer. Particularly, the 5Do-?7F2 transition emission of Eu3+ ion is increased to 145% as compared to the original when the concentration of Gd3+ ion is 3%.
Keywords/Search Tags:Sr2CeO4, Sr2CeO4:Ln, Luminescence, Eenergy transfer, Microwave radiation
PDF Full Text Request
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