Enhancement of red fluorescence and afterglow in CaTiO₃: Pr³⁺ by addition of Lu₂O₃

CaTiO₃: Pr³⁺ with addition Lu₂O₃ are synthesized by conventional solid-state reaction methods. It is found that the addition of Lu leads to the enhancement of red fluorescence and phosphorescence at 615 nm originating from ¹D₂→³H₄ transition of Pr³⁺, following the increase of the lifetime for the ¹D₂ state. As a result, it is indicated that the non-radiative centers for the ¹D₂ state are suppressed by the addition of Lu ions. The persistent time of the afterglow is observed to increase from less than 15 min to over 2 h after the addition of 5 mol% Lu₂O₃. A tentative mechanism of the Lu-addition effect on the optical properties is discussed.