Bell Anthony M T, Henderson C Michael B, Wendlandt Richard F, Harrison Wendy J
Acta Crystallogr Sect E Struct Rep Online. 2008 Aug 23;64(Pt 9):i63-i64. doi: 10.1107/S1600536808026901.
The apatite-type compound Ba(5)(AsO(4))(3)Cl, penta-barium 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)(YO(4))(3)X (A = divalent cation, Y = penta-valent cation, X = Cl, Br) in space group P6(3)/m. The structure consists of isolated tetra-hedral 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 2b sites ( symmetry) and are located in the channels of the structure.
磷灰石型化合物Ba₅(AsO₄)₃Cl，即五钡三[砷酸盐(V)]氯化物，是通过高温离子交换，以副产物BaCO₃从合成的砷铅矿（Pb₅(AsO₄)₃Cl）样品中合成得到的。基于高分辨率同步辐射X射线粉末衍射数据的Rietveld精修结果表明，标题化合物与通式为A₅(YO₄)₃X（A = 二价阳离子，Y = 五价阳离子，X = Cl、Br）的其他卤代磷灰石在空间群P6₃/m中具有相同的晶体结构。该结构由孤立的四面体AsO₄³⁻阴离子（m对称性）组成，由分别位于镜面和三重旋转轴上的两个晶体学独立的Ba²⁺阳离子隔开。Cl⁻阴离子位于2b位点（对称性），并位于结构的通道中。
