Hierarchical ZnO Nanostructures

Nano Letters

Volumn 2, Issue 11, 2002, Pages 1287-1291

  Lao, Jing Yu ^a   Wen, Jian Guo ^a   Ren, Zhi Feng ^a  

^a BOSTON COLLEGE   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0001192839     PISSN: 15306984     EISSN: None     Source Type: Journal    
DOI: 10.1021/nl025753t     Document Type: Article

References (22)

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18. 3 core nanowire. The third symbol * means that the secondary nanorods are having an angle with the major core nanowire. The number 1 or 2 after the symbol * means that not all the secondary ZnO nanorods branches have an angle with the core nanowire.
19. Wen, J. G.; Lao, J. Y.; Wang, D. Z.; Ren, Z. F., in preparation.
20. Powder Diffraction File Release 2000, PDF Maintenance 6.0 (International Center for Diffraction Data, Pennsylvania).
21. The TEM specimen were prepared as follows. As-synthesized nanomaterials were scratched off the graphite foil onto a holey carbon TEM specimen grid, then a drop of acetone was applied to disperse the nanomaterials so that individual nanostructures can be easily examined. Because of the projection nature of TEM image and multiple arms of the nanorods, TEM images of these nanomaterials are always complex to study. Furthermore, clear diffraction contrast images of the cores cannot be obtained in such a configuration due to their large thickness along the electron beam direction. Cross-sectional TEM along the core nanowire direction was introduced to observe the core structure and the orientation relationship between the arms and the core. Samples for cross-sectional TEM were prepared as follows. Given the brittle nature of the nanomaterials, we penetrated the films with M-Bond 610 epoxy resin (M-Line Accessories, Raleigh, NC) to provide mechanical stiffness. M-Bond 610 epoxy has very low viscosity and curing is time and temperature dependent. The viscosity of the epoxy is very low, so it easily impregnates pores and structure of nanomaterials can be preserved. The sample was cured at a temperature of 120 °C for 2 h. The hardened thin foils containing graphite substrate were then cut, glued together following the standard cross-sectional TEM sample preparation technique. Mechanical thinning by a tripod polisher and ion milling (low angle, voltage, and current) was done to thin the sample to electron transparency. Before TEM observation, a low voltage and gun current were used to polish both sides for 10 min.
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