Low temperature synthesis of Na2Eu(CO3)F2.5(OH)0.5, luminescence and crystal field study of Eu3+

The luminescence of Eu3+ in sodium europium hydroxyfluoride carbonate, Na2Eu(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 spectrum consists of groups of sharp lines attributed to D-5(0)-->F-7(0-4) transitions of one low symmetry site for Eu3+ in agreement with the crystallographic analysis. 23 from 25 expected electronic levels for F-7(J) (J=0-4) manifolds are fitted by the phenomenological crystal field parameters in the approaching C-2v point symmetry. The simulation is achieved with very good root mean square (rms) deviation of 5.3 cm(-1). The crystal field strength parameter, 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.