Recombination luminescence of CaSO4:Tb3+ and CaSO4:Gd3+phosphors

Abstract

Abstract:A comparative study of the excitation of luminescence by VUV radiation as well as of thermally and photostimulated luminescence has been carried out for CaSO 4 :Tb 3+ and CaSO 4 :Gd 3+ phosphors, where Na + or F -ions are used for charge compensation. The distinction in hole processes for the phosphors with Na + or F -compensators is determined by the differing thermal stability of the holes localized at/near Tb 3+ Na + and Gd 3+ Na + (up to 100-160 K) or at/near Tb 3+ F -V Ca and Gd 3+ F -V Ca centers involving also a cation vacancy (up to 400-550 K). Tunnel luminescence in the pairs of localized electrons and holes nearby Tb 3+ or Gd 3+ has been detected. The mechanisms of electron-hole, hole-electron and tunnel recombination luminescence as well as a subsequent released energy transfer to RE 3+ ions are considered. PACS

Electronic excitations and self-trapping of electrons and holes in CaSO4

“…In the present study, the peculiarities of complicated electron-hole processes in pure and doped anhydrite will be considered on the basis of a comparison of the experimental data obtained for CaSO 4 doped with Gd 3+ , Tb 3+ , Dy 3+ (see also our previous publications [5,6,8,9]), Tm 3+ rare-earth ions, and theoretical calculations of the electronic properties in a number of calcium oxides and halides [10] with a detailed consideration of CaSO 4 . Results from the literature on detailed investigations of many wide-gap materials doped with RE 2+ and RE 3+ ions have been taken into consideration as well (see [11][12][13] and references therein).…”