Rutile Superstructure of Sb_0.9V_1.1O₄

The structure of Sb_0.9V_1.1O₄, antimony vanadium oxide, has been studied by powder X-ray diffraction, electron diffraction and high-resolution electron microscopy (HREM). The X-ray powder diffraction pattern showed only basic rutile reflections [a_r = 4.6085 (1), c_r = 3.0867 (1) Å] and the basic rutile structure was refined using the Rietveld method. A rutile superstructure was revealed when the sample was studied by electron diffraction. The electron diffraction patterns were indexed on the unit cell a = 2^1/2a_r, b = 2^1/2b_r, c = 2c_r. Its space group, I4₁md, was determined by means of convergent-beam electron diffraction (CBED). A structural model based on alternating cation ordering along c in the chains of edge-sharing octahedra is proposed and its electron diffraction patterns and HREM image are calculated and matched with the experimental ones.

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