Preparation And Luminescence Properties Of Rare-earth Doped SiO₂Microspheres

Since the society has been developed more and more quickly, people’srequirements of luminescent materials are also getting higher and higher.Luminescent materials has experienced from fire, oil to electricity. The tools alsounderwent so many changes, such as torch, candle, kerosene lamp, incandescent lightbulb and so on, and they all owed to the great people’s intelligence. However, theresearchers keep on exploring to prepare more environmental and multifunctionalluminescent materials. Rare-earth doped SiO2nanometer materials have shown agood application in luminescent materials as its good stability and strong emission. Inthis work, SiO2was used as the matrix, firstly to explore the optimal synthesisconditions of SiO2microspheres. Then rare-earth Eu3+doped SiO2microspheres wereprepared. And enventually we prepared Eu3+,Gd3+codoped SiO2andSiO2:Eu(TTFA)3microspheres to improve the luminescent properties. In addition, weused SEM, XRD, TG-DSC, FT-IR and PL to characterize the products. The results ofthe research work are as follows:1. We explored the synthesis conditions to prepare SiO2microspheres under acidand alkaline conditions respectively. We can get the ideal products whose surfaces ofthese microspheres are smooth under alkaline conditions. And different factors on themorphology and particle size such as the temperature, the volumes of NH3·H2O andTEOS were studied. The SiO2microspheres prepared under acid conditions have badhomogeneity. Therefore, we used the alkaline conditions to prepare SiO2microspheres as the “seed” in the seeded growth method. 2. We have succeeded in preparing SiO2:Eu3+microspheres in the seeded growthmethod. Three methods (the base-catalyzed method, the acid-catalyzed method andthe seeded growth method) have used to prepare SiO2:Eu3+microspheres. The resultsindicated that the best method was the seeded growth method. The final productshave nice homogeneity, monodispersity and sphericity. The final SiO2:Eu3+microspheres showed stronger red emission under ultraviolet excitation than theluminescent intensity in the base-catalyzed method and the acid-catalyzed method.3. Eu3+,Gd3+codoped SiO2and SiO2:Eu(TTFA)3microspheres have beensynthesized successfully by changing the conditions to improve the luminescentproperties. The results showed that the SiO2microspheres which codoped withEu3+,Gd3+had smooth surface and good sphericity, and the other products were not.Under the UV excitation, they all showed stronger red emission than SiO2:Eu3+microspheres.