Crystallographic-shear-phase-driven W₁₈O₄₉ nanowires growth on nanocrystalline W surfaces

The present paper reports the growth and branching mechanism of W₁₈O₄₉ nanowires grown on nanocrystalline tungsten (W) surfaces. Nanocrystalline W powder was prepared using high energy ball milling. The nanopowder was non-isothermally heat-treated up to 1400 °C in argon atmosphere. The nanowires of 30–50 nm diameter were observed on nanopowder surfaces after the heat-treatment. A model based on crystallographic shear phase formation to accommodate the oxygen deficiency during the reduction of WO₃ is discussed to explain the growth and branching mechanism of these nanowires which correlates well with the observed angle for the branching.