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Crystal structure determination of lithium diborate hydrate, LiB 2 O 3 (OH).H 2 O, from X‐ray powder diffraction data collected with a curved position‐sensitive detector
Author(s) -
Louër D.,
Louër M.,
Touboul M.
Publication year - 1992
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889892004801
Subject(s) - crystallography , crystal structure , diffractometer , hydrate , rietveld refinement , powder diffraction , x ray crystallography , chemistry , materials science , diffraction , geometry , physics , optics , mathematics , organic chemistry
The crystal structure of lithium diborate hydrate, LiB 2 O 3 (OH).H 2 O, has been solved ab initio and refined by the Rietveld method from powder diffraction data collected with a curved position‐sensitive detector (INEL CPS120) using Debye–Scherrer diffraction geometry with monochromatic X‐rays. In the first stage the indexing of the powder pattern was performed by the successive dichotomy method from data collected with a diffractometer using Bragg–Brentano geometry. The lattice parameters are a = 9.7984 (10), b = 8.2759 (7) and c = 9.6138 (8) Å and the space group is Pnna . The structural model was obtained from direct methods and two difference Fourier maps. The Rietveld refinement converged to final crystal structure and profile indicators R F = 0.05, R B = 0.05, R p = 0.03 and R wp = 0.04. The structure consists of BO 4 tetrahedra ( T ) and BO 2 (OH) triangles (Δ) sharing corners in order to form infinite chains along [010], with the shorthand notation 3:∞ 1 (Δ + 2 T ). The particular linkage of the B 3 O 3 rings leads to a new diborate anion {[B 2 O 3 (OH)] n − n }, in which two tetrahedral B atoms have an occupation factor of 0.5. Li atoms, tetrahedrally surrounded by four O atoms, three belonging to separate chains and one to a water molecule maintain the cohesion of the structure.