Nanostructural Evolution: From One-Dimensional Tungsten Oxide Nanowires to Three-Dimensional Ferberite Flowers

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• 作者：Weibing Hu ; Yimin Zhao ; Zuli Liu ; Charles W. Dunnill ; Duncan H. Gregory ; Yanqiu Zhu
• 刊名：Chemistry of Materials
• 出版年：2008
• 出版时间：September 9, 2008
• 年：2008
• 卷：20
• 期：17
• 页码：5657-5665
• 全文大小：378K
• 年卷期：v.20,no.17(September 9, 2008)
• ISSN：1520-5002

文摘

Based on a W₁₈O₄₉ nanowire template, iron-substituted W₁₈O₄₉ nanowires and FeWO₄ ferberite flowers have been generated by using mixed FeCl₃ and WCl₆ at different ratios in a simple solvo-thermal process employing cyclohexanol as the solvent. Detailed characterization by electron microscopy and spectroscopy has shown that increasing the FeCl₃ concentration during solvo-thermal synthesis promotes a morphological evolution from the long one-dimensional nanowires of the precursor through short Fe-containing W₁₈O₄₉ nanowires and two-dimensional platelets to three-dimensional flowers with sixfold symmetry. The driving force for these transformations is attributed to Fe inclusion in the W₁₈O₄₉ template at low Fe concentrations, which introduces internal stresses to the W₁₈O₄₉ nanowires. At high Fe concentrations, close to the stoichiometric composition of FeWO₄, the formation of the flower is triggered by the intrinsic sixfold symmetry of crystalline ferberite, via a combination of initial nanoblade nucleation and the competing self-assembly of neighboring parallel nanoblades. A similar solvo-thermal process has also been successful in the synthesis of MnNb₂O₆ bronze flowers, which exhibit structures with a morphology resembling a purposely carved microgear. Photoluminescent and magnetic properties of the products are also investigated.