Selective Growth of Monoclinic and Tetragonal Zirconia Nanocrystals
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- 作者：Kazuyoshi Sato ; Hiroya Abe ; Satoshi Ohara
- 刊名：Journal of the American Chemical Society
- 出版年：2010
- 出版时间：March 3, 2010
- 年：2010
- 卷：132
- 期：8
- 页码：2538-2539
- 全文大小：155K
- 年卷期：v.132,no.8(March 3, 2010)
- ISSN：1520-5126
文摘
The growth of metal oxide nanocrystals with a well-organized crystalline phase is of fundamental and technological interest because in this way it is possible to tune their size-dependent unique properties. In this communication, we demonstrate the selective growth of monoclinic and tetragonal ZrO2 nanocrystals of <10 nm diameter driven by controlling the surface energy, with and without capping by N(CH3)4+. The nanocrystals were grown in aqueous solution at 150 °C. It was revealed, by transmission electron microscopy, X-ray diffraction, Raman spectroscopy, and optical absorption studies, that the nanocrystals capped by N(CH3)4+ have a less defective pure monoclinic phase, while those without capping have a pure tetragonal phase with highly disordered oxygen vacancies. The N(CH3)4+ capping on the surface oxygen site can reduce the surface energy low enough to stabilize the monoclinic phase. By contrast, the bare surface oxygen site has higher energy; thereby, the lower surface energy tetragonal phase is formed spontaneously. The present concept is a promising universal approach to control the crystal phases of technologically important oxide nanocrystals