title: Dipotassium tristrontium dimanganese tris(diphosphate).
abstract: The structure of the title mixed trimetallic diphosphate, K(2)Sr(3)Mn(2)(P(2)O(7))(3), is constructed of a three-dimensional matrix composed of SrO(8-10), MnO(5) and PO(4) polyhedra. The sharing of O atoms between these polyhedra creates tunnels of large dimensions parallel to (010), in which are found columns of K(+) ions. Thus, the presence of several cations differing in size in the solid matrix leads to the formation of large tunnels and potential conductivity.