A spectroscopic study of K2YF5 : Pr3+

(Pr3+) D-1(2)-red emission and (Pr3+)P-3(0)-blue emission are observed in K 2YF5:Pr3+ under P-3(0.1) and D-1(2) excitations. Based on the analysis of t he relative emission intensities and the luminescence decays we have conclu ded that both phenomenon occur respectively by means of cross-relaxation, r ather from P-3(1), and up-conversion energy transfer. Such effects have bee n linked to Pr3+ ion-clustering favoured by the 1D-character of the structu re. (C) 2001 Elsevier Science B.V. All rights reserved.