High Resolution Electron Microscopy Study of Nanocubes and Polyhedral Nanocrystals of Cerium(IV) Oxide

Autor(es)

Cordeiro, Marco A. L. ^[1] ; Weng, Weihao ^[2] ; Stroppa, Daniel G. ^[3] ; Kiely, Christopher J. ^[2] ; Leite, Edson R. ^[4]

Afiliação do(s) autor(es)

^[1] Univ Fed Sao Carlos, Dept Mat Sci & Engn, BR-13565905 Sao Carlos, SP - Brazil

^[2] Lehigh Univ, Dept Mat Sci & Engn, Bethlehem, PA 18015 - USA

^[3] Brazilian Synchrotron Light Lab, BR-13083970 Campinas, SP - Brazil

^[4] Univ Fed Sao Carlos, Dept Chem, BR-13565905 Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: CHEMISTRY OF MATERIALS; v. 25, n. 10, p. 2028-2034, MAY 28 2013.
• Citações Web of Science: 20

Resumo

In this research, high resolution transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) studies of ceria(IV) oxide CeO2 nanocrystals (NCs) synthesized by a hydrothermal/two phase process were conducted. The synthesis route affords the possibility of controlling the shape of the CeO2 NCs 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] termination facets. Increasing the {[}OLA]/{[}Ce3+] ratio to 8, while maintaining a constant reaction time and temperature during the synthesis, truncated cube-like CeO2 NCs with [200], [220], and [111] termination facets was generated. These morphologies were identified by HRTEM and HAADF-STEM characterization. Fourier transform infrared (FT-IR) analysis and thermogravimetric analysis (TGA) confirm the presence of chemically bonded oleic acid (OLA) on the CeO2 NC surface. It indicates that there is a relationship between the bonded OLA and the shape of the NC. Additionally, the identification of concave surfaces on [200] facets by HAADF-STEM characterization suggests that the formation of the cube-like CeO2 morphology is a multiple step mechanism. On the basis of these observations new growth mechanisms for the CeO2 morphology variants are proposed. (AU)

• Processo FAPESP: 09/50604-4 - Estudo da sintese de nanocristais de ceo2 e zros e a sinterizacao por microscopia eletronica de transmissao in situ.
• Beneficiário: Marco Aurélio Liutheviciene Cordeiro
• Modalidade de apoio: Bolsas no Brasil - Doutorado