OPTICAL-PROPERTIES OF BAEU(CO3)(2)F AND NA3LA2(CO3)(4)F-EU3+ - CORRELATIONS TO THE CRYSTALLOGRAPHIC STRUCTURES

The luminescent properties of trivalent europium are analyzed in Na3La2(CO3)(4)F:Eu3+ at 77 and 9 K and in BaEu(CO3)(2)F at 77 K. In BaEu(CO3)(2)F, the C-3v symmetry of the rare earth, deduced from the X ray diffraction study, is confirmed. In Na3La2(CO3)(4)F, the spectroscopic technique shows that the order which appears at low temperature implies a single site for the rare earth with a C-3v or a C-3 symmetry. For both compounds, the energy level scheme of the F-7(J) (J = 0-4) levels is well reproduced (weak RMS standard deviation) from six crystal field (cf) parameters consistent with the C-3v site symmetry. (C) 1995 Academic Press, Inc.