文章基本信息

标题：Metastability of anatase: size dependent and irreversible anatase-rutile phase transition in atomic-level precise titania
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作者：Norifusa Satoh ; Toshio Nakashima ; Kimihisa Yamamoto 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2013
卷号：3
DOI：10.1038/srep01959
出版社：Springer Nature
摘要：Since crystal phase dominantly affects the properties of nanocrystals, phase control is important for the applications. To demonstrate the size dependence in anatase-rutile phase transition of titania, we used quantum-size titania prepared from the restricted number of titanium ions within dendrimer templates for size precision purposes and optical wave guide spectroscopy for the detection. Contrary to some theoretical calculations, the observed irreversibility in the transition indicates the metastablity of anatase; thermodynamics cannot explain the formation of metastable states. Therefore, we take into account the kinetic control polymerization of TiO₆ octahedral units to explain how the crystal phase of the crystal-nucleus-size titania is dependent on which coordination sites, cis - or trans -, react in the TiO₆ octahedra, suggesting possibilities for the synthetic phase control of nanocrystals. In short, the dendrimer templates give access to crystal nucleation chemistry. The paper will also contribute to the creation of artificial metastable nanostructures with atomic-level precision.