Sensitized luminescence through nanoscopic effects of ZnO encapsulated in SiO2:Tb3+ sol gel derived phosphor

Terbium (1 mol%) doped ZnO–SiO2 binary system was prepared by a sol–gel process. Nanoscopic effects of ZnO on the photoluminescence (PL) and the cathodoluminescence (CL) properties were studied. Defects emission from ZnO nanoparticles was measured at 560 nm and the line emission from Tb3+ ions in SiO2:Tb3+ and ZnO–SiO2:Tb3+ with a major peak at 542 nm was measured. The PL excitation wavelength for 542 nm Tb3+ emission was measured at ∼320 nm in both SiO2:Tb3+ and ZnO–SiO2:Tb3+. The CL data showed quenched luminescence of the ZnO nanoparticles at 560 nm from a composite of ZnO–SiO2:Tb3+ and a subsequent increase in 542 nm emission from the Tb3+ ions. This suggests that energy was transferred from the ZnO nanoparticles to enhance the green emission of the Tb3+ ions. The PL and CL properties of ZnO–SiO2:Tb3+ binary system and possible mechanism for energy transfer from the ZnO nanoparticles to Tb3+ ions are discussed.