Laser or synchrotron radiation induced luminescence spectroscopy was used to analyze the intense fluorescence of Eu3+ ions embedded in K2YF5 and K2GdF5. The use of Time Resolved Spectroscopy in combination with the variation of both temperature and Eu3+ concentration leads to the identification of the electronic levels of Eu3+ ion after excitation in the 5D2, 5D1 and 5D0 manifolds. The spectral features of the Eu3+ fluorescence agree with an Eu3+ ion located on lattice site of point symmetry C1. At low temperature, below 100 K, weak extra lines extending over a range of few wavenumbers were observed on both sides of the main 7F0 → 5D0-2 excitation lines. Recording the luminescence spectra and luminescence decays under excitation in the main and satellite lines has suggested the attribution of the extra lines to signature of Eu3+ pairs, the occurence of which is favoured by the one-dimensional character of the crystal structure. Photon cascade and quantum cutting involving Gd3+ and Eu3+ ions have been evidenced in K2GdF5: Eu3+ under VUV excitation. The 1-D character of the structure seems to be unfavourable for the design of phosphors exhibiting quantum yield higher then unity.
