A novel modification of manganese orthophosphate Mn3(PO4)2

A new third modification of manganese(II) orthophosphate Mn3(PO4)2 has been obtained under hydrothermal conditions. Its crystal structure was determined by single crystal X-ray diffraction: space group P21/n, Z=2, a=5.2344(5), b=6.6739(7), c=8.9688(10)Å, β=95.276(9)° at 293 K, wR2=0.050, R=0.019. In the structure, [MnO5] polyhedra and [MnO6] octahedra in a ratio of 2:1 share common edges to form chains alternating along the [110] and [1¯10] directions. They are further linked by common vertices and the phosphate tetrahedra to a 3D framework. The relations of this new structure type to the other polymorphs of Mn3(PO4)2 and related Mn and Fe phosphates are discussed.