- Journal Article
The oxidation of Nb7W10O47 at relatively low temperature TOX = 500 °C leads to the formation of domains of the Nb8W9O47 structure between which coherently embedded planar defects appear. The basic Nb8W9O47 structure was identified by powder X-ray diffraction (XRD) and subsequent Rietveld refinement. The structure of the planar defects building up the boundaries was determined by scanning transmission electron microscopy (STEM) images recorded with a high-angle annular dark field (HAADF) detector and an annular bright field (ABF) detector. We compare STEM images of the well-known Nb8W9O47 structure with images of the oxidation product of Nb7W10O47 and show that domains of Nb8W9O47 are also present while additional coherently embedded planar defects appear. HAADF-STEM images reveal that these defects often comprise arrays of three hexagons of octahedra that are locally arranged in a one-dimensional periodic way. ABF-STEM images reveal that two pairs of octahedra in one of the hexagons are actually connected by edge-sharing instead of the usual and hitherto assumed corner-sharing. © 2021 Elsevier Show more
Journal / seriesJournal of Solid State Chemistry
Pages / Article No.
SubjectNiobium tungsten oxides; Tungsten bronzes; Scanning transmission electron microscopy; Annular bright field; ABF-STEM
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