Luminescence of BaF2-LaF3

The luminescence properties of Ba1-xLaxF2+x single crystals have been inves tigated for La concentrations up to 5 mol%. The luminescence spectra of the crystals have been recorded during X-ray excitation, The intensity of the exciton emission in BaF2-5% LaF3 is reduced by a factor of 10, whereas the intensity of the cross-luminescence remains almost constant. Besides the ma in emission bands of the cross-luminescence at 6.3 and 5.6 eV, an additiona l weak emission band at about 7.2 eV has also been observed. We suggested t hat the newly observed emission arises from a radiation transition between the interstitial F-i(-)-ion and the outermost Ba2+ 5p core band. We found t hat with increasing La-doping, the edge of fundamental absorption of Ba1-xL axF2+x crystals shifts to lower energies. (C) 2001 Elsevier Science Ltd. Al l rights reserved.