Luminescence kinetics in silica gel doped with Tb3+ ions and ZnS:Mn2+ nanocrystals

Luminescence kinetics and time-resolved luminescence spectra of SiO2, SiO2 doped with ZnS:Mn2+ nanocrystals and SiO2 doped with ZnS:Mn2+, and additionally co-doped with Tb3+, are presented. The purposes of the paper are the analysis of the kinetics of the Tb3+ and Mn2+ intra-shell luminescence and the elucidation of the energy-transfer mechanism between the ZnS:Mn2+ nanocrystals and the Tb3+ ions. We have found a blue luminescence related to defects in the ZnS nanocrystals and an intrinsic luminescence of the SiO2 lattice, which decays in few ns. A yellow luminescence related to the Mn2+ 4T1(G)→6A1 transition and yellow sharp lines related to the 5D4→7F6, 7F5, 7F4 and 7F3 transitions in Tb3+ are found to decay in ms. A very effective energy transfer between ZnS:Mn2+ nanoparticles and Tb3+ ions has been observed.