Spectroscopic studies of the Eu3+ and Er3+ ions in the fluorozirconate LaZr2F11 matrix

An investigation by optical spectroscopy of the Eu3 + and Er3 + active ions in the crystallized fluorozirconate matrix LaZr2F11 is presented. The D-5( 1) --> F-7(0-5) emission lines of Eu3 + are used to extract the F-7(0-5) en ergy scheme and the observed extinctions permit the deduction of irreducibl e representations (IRREPS) associated with corresponding sub-levels in the D-2 symmetry. The crystal field analysis was carried out on a 387 x 387 bas is set, comprising the F-7, D-5(1,2,3) F-5(1,2), (5)G(1,2,3) and P-3(1,2,3, 4,5,6) terms of the Eu-3 (+) 4f(6) configuration. The deviation and rms are 6.8 and 7.9 cm (-1), respectively for 38 levels and ten parameters. The ex perimental crystal field parameters are in good agreement with the ab-initi o ones. Moreover, the relative intensities of the D-5(0) --> F-7(2,3,4) emi ssions are well reproduced by an 'ab-initio' calculation, except for three lines. The Er3 + ions introduced in LaZr2F11, microcrystals also lie in an unique crystallographic site. A total of 31 energy levels were recorded and the crystal field analysis led to 6.6 and 7.8 cm (-1) for the deviation an d rms, respectively, for nine variable parameters taken into account. The e xperimental CF parameters for Er3 + and Eu3 + are very similar, which seems to show that the host lattice contracts around the smaller Er3 + ion. The informations given by both Eu3 + and Eu3 + optical probes in LaZr2F11 are v ery consistent with the structure previously determined for the isotypic Pr Zr2F11 fluoride. (C) 2000 Elsevier Science B.V. All rights reserved.