Na1.50Mn2.48Al0.85(PO4)3, a new synthetic alluaudite‐type compound

The first hydro­thermal synthesis of an Al‐rich alluaudite‐type compound, namely disodium dimanganese aluminium tris­(phosphate), which has been obtained at 1073 K and 0.1 GPa starting from the composition Na₂Mn₂Al(PO₄)₃, is reported. The crystal structure, which has been refined in the monoclinic C2/c space group, is identical to that of natural alluaudite. The structure consists of kinked chains of edge‐sharing M1 and M2 octa­hedra, which contain Mn²⁺ and Al³⁺ ions. The chains are stacked parallel to {101} and are connected in the b direction by the P1 and P2 tetra­hedra. These inter­connected chains produce channels parallel to c, which contain the large A1 and A2′ sites occupied by Na⁺ and Mn²⁺ ions.