Enhanced luminescence and degradation of SiO2:Ce,Tb powder phosphors prepared by a sol–gel process

Abstract

Abstract Enhanced green photoluminescence and cathodoluminescence (CL) from Tb 3+ ions due to co-doping with Ce 3+ ions were observed from SiO 2 :Ce,Tb powder phosphors prepared by a sol–gel technique. Blue emission from the Ce 3+ ions was completely suppressed by Tb co-doping, presumably due to energy transfer from Ce 3+ to Tb 3+ . In addition, the green CL intensity from SiO 2 :Ce,Tb degraded by ∼50% when the powders were irradiated for 10 h with a 2 keV, 54 mA/cm 2 beam of electrons in an ultra-high vacuum chamber containing either 1×10 −8 or 1×10 −7 Torr O 2 . Desorption of oxygen from the surface was observed during the decrease of CL intensity. The mechanisms for energy transfer from Ce 3+ ions to Tb 3+ 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.