UV-to-red relaxation pathways in CaTiO3:Pr3+

Abstract The radiationless relaxation pathways leading to the quenching of 3 P 0 emission and subsequent atypical single red luminescence from 1 D 2 level in CaTiO 3 :Pr 3+ are studied under UV excitation. Self-trapped excitons are shown to participate in the relaxation process and Pr 3+ /Ti 4+ ⇋Pr 4+ /Ti 3+ charge transfer state (CTS) is proposed as the final relaxation channel to the emitting 1 D 2 level. This mechanism is supported by EPR investigations showing an increase of paramagnetic [Pr 4+ Ti 3+ O 3 ] + clusters upon optical excitation in the CTS.