Homologues of Mo4O11(mon) in the Mo-W-O System Prepared by Soft Chemistry

Abstract In specimens prepared by gentle reduction of the mixed oxide Mo 0.72 W 0.28 O 3 (ReO 3 -type structure) phases isotypic of the monoclinic form of Mo 4 O 11 have been observed and characterized by electron diffraction and high resolution electron microscopy techniques. The structures are built up of corner-sharing M O 6 octahedra in ReO 3 -type slabs of different widths ( m ), connected by M O 4 tetrahedra so that alternating four- and six-sided tunnels are formed. The phases are considered as members m = 7 and m = 8 of a homologous series of structures with the general formula M m +2 O 3 m +4 , where Mo 4 O 11 is the member m = 6. General expressions for the unit cell dimensions are given. Some defects are observed and models are proposed.