Refinement of the cation distribution in Nb-Mo double oxide

The structure of Nb2Mo3O14 double oxide is refined from powder data using synchrotron radiation and the anomalous scattering effect; space group P (4) over bar2(1)m is found for the material. It is demonstrated that in the tetragonal unit cell with parameters a = 23.173 angstrom, c = 4.0027 angstrom Nb5+ and Mo6+ ions are stochastically distributed in MO6 octahedra and MO7 pentagonal bipyramids of the polygonal network structure of the Mo5O14 type.