title: Rietveld refinement of AgCa10(PO4)7 from X-ray powder data.
abstract: Polycrystalline silver(I) deca-calcium heptakis(orthophos-phate), AgCa10(PO4)7, was obtained by solid-state reaction. It is isotopic with members of the series MCa10(PO4)7 (M = Li, Na, K and Cs), and is closely related to the structure of β-Ca3(PO4)2. The crystal structure of the title compound is built up from a framework of [CaO9] and two [CaO8] polyhedra, one [CaO6] octa-hedron (site symmetry 3.) and three PO4 tetra-hedra (one with site symmetry 3.). The Ag(+) cation is likewise located on a threefold rotation axis and resides in the cavities of the rigid [Ca10(PO4)7](-) framework. It is surrounded by three O atoms in an almost regular triangular environment.
authors.affiliation: Department of Inorganic Chemistry, Taras Shevchenko National University, 64/13 Volodymyrska str., 01601 Kyiv, Ukraine.
authors.forename: Nataliya Yu
authors.initials: NY
authors.lastname: Strutynska
authors.forename: Igor V
authors.initials: IV
authors.lastname: Zatovsky
authors.forename: Ivan V
authors.initials: IV
authors.lastname: Ogorodnyk
authors.forename: Nikolay S
authors.initials: NS
authors.lastname: Slobodyanik