K0.53Mn2.37Fe1.24(PO4)3

During an attempt to crystallize potassium manganese diiron phosphate KMnFe2(PO4)(3) by the flux method, a new phase, potassium dimanganese iron triphosphate, K0.53Mn2.37Fe1.24-(PO4)(3), was isolated. This phase, whose composition was confirmed by ICP analysis, is isotypic with the alluaudite-like phosphates, thus it exhibits the (A2)(A'2)(A1)(A'1)(A '' 1)-(M1)(M2)(2)(PO4)(3) general formula. The site occupancies led to the following cation distribution: 0.53 Kon A'2 (site symmetry 2), 0.31 Mn on A '' 1, 1.0 Mn on M1 (site symmetry 2) and (0.62 Fe + 0.38 Mn) on M2. The structure is built up from infinite chains of edge-sharing M1O(6) and M2O(6) octahedra. These chains run along [10 (1) over bar] and are connected by two different PO4 tetrahedra, one of which exhibits 2 symmetry. The resulting three-dimensional framework delimits large tunnels parallel to [001], which are partially occupied by the K+ and Mn2+ cations.