An X-Ray and Electron Diffraction Study of the Intergrowth Tungsten Bronze Sb0.16WO3

The average structure of the orthorhombic antimony tungsten bronze, Sb0.16WO3, has been resolved by three-dimensional single-crystal X-ray diffraction (space groupPmmm,aav= 7.4261(7),bav=10.2004(15),cav=3.8061(7) Å, andZ=5). The structure refinement based on 377 observed unique reflections withI>2σ(I) (3493 totally measured reflections) converged toR=0.064. The structure is of the intergrowth tungsten bronze type (ITB), consisting of slabs of hexagonal tungsten bronze structure (HTB) interchanged with slabs of perovskite-like WO3structure (PTB) along [010]. The HTB slabs are one hexagonal tunnel thick and the PTB slabs are two WO6octahedra thick. The Sb atoms are distributed over two positions inside the hexagonal tunnels. Electron diffraction observations revealed a superstructure withas=2aav,bs=2bav, andcs=4cav, which may be attributed to an ordering of the Sb atoms. A possible structural model is proposed.