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 nm, 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. 3P0 luminescence under UV excitation is completely quenched to 1D2 through a strong coupling with the charge transfer state at room temperature. However, quite strong 3P0 emission was observed at low temperatures when the 3P2 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.