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Enhanced luminescence and degradation of SiO2:Ce,Tb powder phosphors prepared by a sol-gel process |
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| Authors: | OM Ntwaeaborwa HC Swart PH Holloway |
| Institution: | a Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein ZA9300, South Africa b Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611-64, USA c Department of Physics, Nelson Mandela Metropolitan University, Port Elizabeth ZA6031, South Africa |
| Abstract: | Enhanced green photoluminescence and cathodoluminescence (CL) from Tb3+ ions due to co-doping with Ce3+ ions were observed from SiO2:Ce,Tb powder phosphors prepared by a sol-gel technique. Blue emission from the Ce3+ ions was completely suppressed by Tb co-doping, presumably due to energy transfer from Ce3+ to Tb3+. In addition, the green CL intensity from SiO2:Ce,Tb degraded by ∼50% when the powders were irradiated for 10 h with a 2 keV, 54 mA/cm2 beam of electrons in an ultra-high vacuum chamber containing either 1×10−8 or 1×10−7 Torr O2. Desorption of oxygen from the surface was observed during the decrease of CL intensity. The mechanisms for energy transfer from Ce3+ ions to Tb3+ ions to enhance the green luminescence, and mechanisms for desorption of oxygen from the phosphor surface that would result in decreased CL intensity are discussed. |
| Keywords: | Cathodoluminescence Degradation Photoluminescence Energy transfer |
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