Abstract: Structural properties of LnBaB₉O₁₆(Ln=La, Y) were investigated by means of X-ray powder diffraction, electron diffraction and luminescence. These compounds crystallize in the monoclinic crystal system with lattice parameters a =1.3660 nm, b=0.7880 nm, c=1.6253 nm and β=106.15° for LaBaB₉O₁₆and a =1.3476 nm, b=0.7776 nm, c =1.6040 nm and β = 106.38° for YBaB₉O₁₆. The study of luminescence spectra of Eu³⁺doped materials reveals that the structures of these two compounds are different. The local symmetry of the rare earth ions is central symmetric in YBaB 9O₁₆and non-central symmetric in LaBaB₉O₁₆. The emission intensity of LaBaB₉O₁₆:Eu³⁺is enhanced by partial substitution of La³⁺with Gd³⁺. Absorption of LaBaB₉O₁₆:Eu³⁺in the VUV region is relatively weak, which may be related to the small ratio of B:O.

Key words: Electron diffraction, X-ray powder diffraction, Luminescence, Borate