Persistent energy transfer in CaAl2O4:Tb3+, Ce3+

Ceramic samples of Tb3+ and Ce3+ singly doped and co-doped CaAl2O4 with 0.1 and 1 at. % doping concentrations have been prepared. The emission of the Ce3+ singly doped sample is at 413 nm. The persistence time of its afterglow is longer than 10 h. The strongest emission of the Tb3+ singly doped sample is at 543 nm and its afterglow persists for about 1 h. In the co-doped sample, the Ce3+ excitation is transferred to Tb3+ ion with an energy transfer rate of 10(9)-10(10) s(-1) in the high concentration samples. The Ce3+ energy transfer occurs during its afterglow decay, so that the Tb3+ afterglow emission duration is also extended to about 10 h. Photoconductivity and thermoluminescence measurements have also been performed in these systems; the persistent sensitization of Tb3+ is also confirmed by these measurements. (C) 2003 American Institute of Physics.