Low temperature synthesis of Na2Eu(CO3)F-2.5(OH)(0.5), luminescence and crystal field study of Eu3+

The luminescence of Eu3+ in sodium europium hydroxyfluoride carbonate, Na2E u(CO3)F-2.5(OH)(0.5), synthesized by hydrothermal growth at low temperature , is presented. The structure is orthorhombic and is built up from EuO3(F, OH)(6) polyhedra linked by triangular faces and edges. The emission spectru m consists of groups of sharp lines attributed to D-5(0)-->F-7(0-4) transit ions of one low symmetry site for Eu3+ in agreement with the crystallograph ic analysis. 23 from 25 expected electronic levels for F-7(J) (J=0-4) manif olds are fitted by the phenomenological crystal field parameters in the app roaching C-2v point symmetry. The simulation is achieved with very good roo t mean square (rms) deviation of 5.3 cm(-1). The crystal field strength par ameter, N-v, is weak (N-v = 1652). Satellite vibronics of carbonate groups coupled to electronic transitions are also observed. (C) 2000 Published by Elsevier Science S.A. All rights reserved.