Na(1.85)Mg(1.85)In(1.15)(PO(4))(3) and Ag(1.69)Mg(1.69)In(1.31)(PO(4))(3) with alluaudite-type structures

Single crystals of two new phosphates, sodium magnesium indium(III) tris­(orthophosphate) and silver magnesium indium(III) tris­(orthophosphate), were obtained from solid-state reactions. The two phosphates are isotypic and exhibit alluaudite-type structures. They are characterized by a cationic disorder of the Mg and In sites and a partial occupation of the Na and Ag sites, respectively. The structure of both phosphates is made up of chains of edge-sharing [(Mg,In)O(6)] octa­hedra extending parallel to [10[Image: see text]]. Adjacent chains are linked by PO(4) tetra­hedra to form a three-dimensional framework delimiting two types of channels parallel to [001] in which the monovalent cations are situated. The coordination numbers of the Na(+) cations are 6 and 8, and for both Ag(+) cations 6. The corresponding coordination spheres are considerably distorted.