Structural and luminescent properties of LnBaB(9)O(16): Eu3+

LnBaB(9)O(16) (Ln = Y, Gd) and europium-doped materials were synthesized by solid-state reactions. The electron and X-ray diffraction studies show tha t these compounds crystallize in the rhombohedral crystal system with the l attice constants a = 7.785(2), c = 46.21(1) Angstrom for YBaB9O16 and a = 7 .809(2), c = 46.47(1) Angstrom for GdBaB9O16. The luminescent spectra of Eu 3+-doped materials reveal that the local symmetry of the rare earth ions is centrosymmetric in YBaB9O16 and noncentrosymmetric in GdBaB9O16. The struc tures of these two compounds are similar and related by symmetry degradatio n, which occurs at about x = 0.1 in the Y1-xGdxBaB9O16 system. (C) 2001 Els evier Science Ltd. All rights reserved.