Luminescence properties of Pr3+ in titanates and vanadates: Towards a criterion to predict 3P0 emission quenching

Luminescence spectra of Pr3+ in 15 titanate and vanadate lattices have been measured under UV excitation. They are characterized by a dominant red luminescence assigned to transitions from the 1D2 level to the ground state. The quenching of the otherwise prominent blue luminescence from 3P0 state is ascribed to a relaxation pathway involving a low-lying Pr3+–Mn+ (Mn+ = Ti4+ or V5+) intervalence charge transfer (IVCT) state. Complete quenching of the 3P0 emission takes place when the IVCT bands are located in the 26 500–28 000 cm−1 range and the shortest Pr3+–Mn+ distances are in the 3.15–3.30 Å range.