1. High ResolutionElectron Microscopy Study of Nanocubes and Polyhedral Nanocrystalsof Cerium(IV) Oxide.
- Author
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Cordeiro, Marco A. L., Weng, Weihao, Stroppa, Daniel G., Kiely, Christopher J., and Leite, Edson R.
- Subjects
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ELECTRON microscopy , *NANOCRYSTAL synthesis , *POLYHEDRAL functions , *CERIUM oxides , *TRANSMISSION electron microscopy , *THERMOGRAVIMETRY , *SURFACE chemistry , *FOURIER transform infrared spectroscopy - Abstract
In this research, high resolutiontransmission electron microscopy (HRTEM) and high angle annular darkfield–scanning transmission electron microscopy (HAADF-STEM)studies of ceria(IV) oxide CeO2nanocrystals (NCs) synthesizedby a hydrothermal/two phase process were conducted. The synthesisroute affords the possibility of controlling the shape of the CeO2NCs by changing the oleic acid/cerium ([OLA]/[Ce3+]) ratio. At a relatively low [OLA]/[Ce3+] ratio of 4,a polyhedral NC morphology was obtained with {111} and {200} terminationfacets. Increasing the [OLA]/[Ce3+] ratio to 8, while maintaininga constant reaction time and temperature during the synthesis, truncatedcube-like CeO2NCs with {200}, {220}, and {111} terminationfacets was generated. These morphologies were identified by HRTEMand HAADF-STEM characterization. Fourier transform infrared (FT-IR)analysis and thermogravimetric analysis (TGA) confirm the presenceof chemically bonded oleic acid (OLA) on the CeO2NC surface.It indicates that there is a relationship between the bonded OLA andthe shape of the NC. Additionally, the identification of concave surfaceson {200} facets by HAADF-STEM characterization suggests that the formationof the cube-like CeO2morphology is a multiple step mechanism.On the basis of these observations new growth mechanisms for the CeO2morphology variants are proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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