The crystal structures of a series of cubic hydrogen insertion compounds of the mixed molybdenum tungsten oxides

Abstract

The structures of three hydrogen insertion compounds, D 0.56Mo 0.25W 0.75O 3, D 0.80Mo 0.5W 0.5O 3, and D 0.81Mo 0.69W 0.31O 3, were determined from powder neutron diffraction studies. All three compounds were body centered cubic (space group Im3) with the unit cell containing eight formula weights. The lattice parameter a = 7.5558(6), 7.587(1), and 7.5743(5) Å, respectively. A least-squares method based on peak intensities was used to determine the structures. The metal atoms lie on the special perovskite sites and are surrounded by nearly regular octahedra of oxygen atoms with the latter displaced from the normal perovskite positions along 〈110〉. The deuterium atoms are distributed over 48 sites in the unit cell and form —OD bonds directed toward the nearest oxygen atom in a neighboring octahedron. These compounds have the same structure as the cubic hydrogen tungsten bronze H 0.53WO 3.