Up‐conversion Luminescence in K2LaX5 (X = Cl, Br, I) Crystals Doped with Pr3+ Ions

A series of crystals of ternary lanthanide halides K2LaX5 (X = Cl,Br,I) doped with Pr3+ were synthesized, crystals grown using the Bridgman method, and their optical properties were studied. Apart from fundamental Pr3+ emission, up-conversion emission was detected in these crystals. Some features in the up-conversion fluorescence vary in the series of halides (Cl, Br, I). Non-radiative energy transfer between Pr3+ ions is observed and up-conversion mechanisms are proposed.