UV excitation and trapping centers in CaTiO3:Pr3

Pr3+:CaTiO3, which produces red emission at 612 nm is an attractive phosphor. Its UV excitation spectrum consists of three bands at 279, 330 and 360 run, which are assigned to the Pr3+ 4f to 5d transition, the valence-to-conduction band transition Ti4+-O2-- to Ti3+-O- and the charge transfer transition Pr3+-Ti4+ to Pr4+-Ti3+, respectively. P-3(0) luminescence under UV excitation is completely quenched to D-1(2), through a strong coupling with the charge transfer state at room temperature. However, quite strong P-3(0) emission was observed at low temperatures when the P-3(2) state was excited at 457.9 nm. In addition, the phosphor showed a red afterglow, which can be enhanced by adding Al3+. The traps are associated with electron trapping, and are possibly related to Pr4+ and oxygen vacancies existing in the samples. (c) 2006 Elsevier B.V. All rights reserved.