Original paper

Reinvestigation of the crystal structure of liberite, Li2BeSiO4

Yang, Zhuming; Ding, Kuishou; Miyawaki, Ritsuro; Li, He


The crystal structure of liberite was refined by single-crystal X-ray methods. Monoclinic, space group P1n1, a = 4.7022(9), b = 4.9443(10), c = 6.1026(12) Å, β = 90.09(3)°, cell content 2× Li2BeSiO4, R 1 = 0.024, wR2 = 0.059. The main features of the atomic arrangement remain unchanged, this means that liberite belongs to a distorted wurtzite-type compound with Be, Si and two kinds of Li in tetrahedral coordination. But in the refined structure the interatomic distances agree with experience in stereo-chemistry: average M-O distances are Be-O = 1.655(10), Si-O = 1.631(4), Li-O = 1.983(13) and 1.973(25) Å, for Li(1) and Li(2), respectively. Also the bond length distortions of the Li(1)O4- and Li(2)O4-tetrahedra, 0.62 and 1.14, respectively, are in agreement with a statistical study of the shape of LiO4-tetrahedra in the literature.