Rietveld refinement of Ba5(AsO4)3Cl from high-resolution synchrotron data

• Published in: Acta crystallographica. Section E, Structure reports online Vol. 64; no. Pt 9; pp. i63 - i64
• Main Authors: Bell, Anthony M. T., Henderson, C. Michael B., Wendlandt, Richard F., Harrison, Wendy J.
• Format: Journal Article
• Language: English
• Published: International Union of Crystallography 01.09.2008
• Subjects: Inorganic Papers
• ISSN: 1600-5368; 1600-5368
• DOI: 10.1107/S1600536808026901

The apatite-type compound Ba 5 (AsO 4 ) 3 Cl, penta­barium tris­[arsenate(V)] chloride, has been synthesized by ion exchange at high temperature from a synthetic sample of mimetite (Pb 5 (AsO 4 ) 3 Cl) with BaCO 3 as a by-product. The results of the Rietveld refinement, based on high resolution synchrotron X-ray powder diffraction data, show that the title compound crystallizes in the same structure as other halogenoapatites with general formula A 5 ( Y O 4 ) 3 X ( A = divalent cation, Y = penta­valent cation, X = Cl, Br) in space group P 6 3 / m . The structure consists of isolated tetra­hedral AsO 4 3− anions ( m symmetry), separated by two crystallographically independent Ba 2+ cations that are located on mirror planes and threefold rotation axes, respectively. The Cl − anions are at the 2 b sites ( symmetry) and are located in the channels of the structure.