Nanostructured Niobates via Phase Transformation
Nanostructured Niobates via Phase Transformation
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DOI：
10.1166/nnl.2011.1170
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发表时间：
2011-06
影响因子：
--
通讯作者：
K. Gao;D. Xue
中科院分区：
文献类型：
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作者：
K. Gao;D. Xue
采用相转化法，通过溶液和固相化学反应合成了具有不同纳米结构的钛酸酯。通过改变氧氟铌酸和H2O2混合溶液中NH3·H2O的加入量，选择性地制备了（NH4）3NbO4F4和（NH4）3NbO8。以所得过氧硼酸盐为前驱体，在溶剂热条件下分别合成了氟掺杂的Nb2O5纳米管和H2Nb2O6空心球。通过适当的煅烧进一步得到了纯的Nb2O5纳米管和空心球。通过X射线衍射仪、扫描电子显微镜和透射电子显微镜对产物和前驱体的结构和形貌进行了表征。在整个合成过程中，相变起着重要的作用。通过亚稳态过氧乙酸盐前驱体的转化得到稳定的过氧乙酸盐，并分别用卷起和Ostwald熟化机制解释了纳米管和空心球的形成过程。所提出的纳米结构纳米材料的合成方案可以扩展到其他技术上重要的纳米材料的化学制造。
A phase-transformation method was developed to synthesize niobates with different nanostructures, through solution- and solid-state chemical reactions. (NH4)3NbO4F4 and (NH4)3NbO8 were selectively prepared by changing the added content of NH3·H2O in the mixed solution of oxofluoroniobic acid and H2O2. The obtained peroxy niobates were respectively employed as precursors for the synthesis of F-doped Nb2O5 nanotubes and H2Nb2O6 hollow spheres under solvothermal conditions. Pure Nb2O5 nanotubes and hollow spheres were further obtained through moderate calcination. The structure and morphology of products and precursors were monitored via X-ray diffractometer, scanning electronic microscopy and transmission electronic microscopy. In the whole synthetic process, phase transformation plays an important role. Stable niobates were obtained from the transformation of metastable peroxy niobates precursors, and the rolling-up and Ostwald ripening mechanisms were respectively employed to explain the evolution processes of nanotubes and hollow spheres. The proposed synthetic scheme for nanostructured niobates can be extended to the chemical fabrication of other technologically important nanomaterials.