Excited states dynamics in the ternary praseodymium and ytterbium/praseodymium halides

The purpose of this paper is investigation of the spectroscopic properties of Pr3+ and Yb3+/Pr3+ co-doped ternary lanthanum halides hosts in the form of powders and correlation of their optical behaviour with the appropriate crystals grown by the Bridgman method. Spectroscopic measurements relevant to laser applications, high resolution absorption and emission spectra at 293 K, 77 K and 4 K as well as emission decay times have been studied. The radiative transition probabilities were analyzed and Judd-Ofelt parameters in K2LaCl5:5%Pr3+ were calculated. A drastic enhancement of the intensities in the powdered halides has been observed as compared to the single crystal spectra. An up-conversion emission has been detected and the observed phenomena are discussed.