High-Pressure Studies on CeO2 Nano-Octahedrons with a (111)-Terminated Surface

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• 作者：Bo Liu ; Mingguang Yao ; Bingbing Liu ; Zepeng Li ; Ran Liu ; Quanjun Li ; Dongmei Li ; Bo Zou ; Tian Cui ; Guangtian Zou ; Jing Liu ; Zhiqiang Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：March 24, 2011
• 年：2011
• 卷：115
• 期：11
• 页码：4546-4551
• 全文大小：840K
• 年卷期：v.115,no.11(March 24, 2011)
• ISSN：1932-7455

文摘

In-situ high-pressure X-ray diffraction and Raman spectroscopies have been performed on well-shaped CeO₂ nano-octahedrons enclosed by eight (111) planes. The CeO₂ nano-octahedrons are shown to be more stable than their bulk counterparts and some other reported CeO₂ nanocrystals of smaller size. The transition pressure from cubic to orthorhombic phase is approximately 10 GPa higher than that of 12 nm CeO₂ nanocrystals even though they have similar volume expansion at ambient conditions. Additionally, the phase transition to 伪-PbCl₂ phase is very sluggish and uncompleted even up to 55 GPa. The TEM image of the sample after decompression from 55 GPa clearly shows that the nano-octahedrons preserve the starting shape. Such distinct high-pressure behaviors in CeO₂ nano-octahedrons have been discussed in terms of their special exposure surface. Further analysis shows that the lower compressibility of the exposed (111) planes in the nano-octahedrons is believed to be the major factor to the elevation of the phase transition pressure and the sluggishness of the transition.