Rietveld refinement of Ba5(AsO4)3Cl from high-resolution synchrotron data
Bell, Anthony M. T.
Henderson, C. Michael B.
Wendlandt, Richard F.
Harrison, Wendy J.
- Publisher: International Union of Crystallography
Acta Crystallographica Section E: Structure Reports Online,
The apatite-type compound Ba5(AsO4)3Cl, pentabarium\ud tris[arsenate(V)] chloride, has been synthesized by ion\ud exchange at high temperature from a synthetic sample of\ud mimetite (Pb5(AsO4)3Cl) with BaCO3 as a by-product. The\ud results of the Rietveld refinement, based on high resolution\ud synchrotron X-ray powder diffraction data, show that the title\ud compound crystallizes in the same structure as other\ud halogenoapatites with general formula A5(YO4)3X (A =\ud divalent cation, Y = pentavalent cation, X = Cl, Br) in space\ud group P63/m. The structure consists of isolated tetrahedral\ud AsO4 3- anions (m symmetry), separated by two crystallographically\ud independent Ba2+ cations that are located on\ud mirror planes and threefold rotation axes, respectively. The\ud Cl- anions are at the 2b sites (3 symmetry) and are located in\ud the channels of the structure.