f–d Luminescence of Pr3+ and Ce3+ in the chloro-elpasolite Cs2NaYCl6

A detailed study of the ultraviolet (UV) luminescence properties of the Pr3+ and Ce3+ ions in the elpasolite crystal Cs2NaYCl6 is reported. The absorption and fluorescence spectra associated with the lowest excited states of the 4f5d and 5d electronic configurations of the Pr3+ and Ce3+ ions, respectively, were recorded both at room temperature and at 77 K. The UV excitation on the Pr3+ ions was provided indirectly via a two step absorption process using the 3P0 level of the 4f2 configuration as an intermediate state. Pr3+ to Ce3+ energy transfer was then clearly evidenced.