Rietveld refinement of AgCa(10)(PO(4))(7) from X-ray powder data

Polycrystalline silver(I) deca­calcium heptakis(orthophos­phate), AgCa(10)(PO(4))(7), was obtained by solid-state reaction. It is isotopic with members of the series MCa(10)(PO(4))(7) (M = Li, Na, K and Cs), and is closely related to the structure of β-Ca(3)(PO(4))(2). The crystal structure of the title compound is built up from a framework of [CaO(9)] and two [CaO(8)] polyhedra, one [CaO(6)] octa­hedron (site symmetry 3.) and three PO(4) tetra­hedra (one with site symmetry 3.). The Ag(+) cation is likewise located on a threefold rotation axis and resides in the cavities of the rigid [Ca(10)(PO(4))(7)](−) framework. It is surrounded by three O atoms in an almost regular triangular environment.