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Surface charges and optical characteristic of colloidal cubic SiC nanocrystals.

Li Y, Chen C, Li JT, Yang Y, Lin ZM - Nanoscale Res Lett (2011)

Bottom Line: Fourier transform infrared spectra show that these cubic SiC nanocrystals contain carboxylic acid, SiH, CH, and CHx groups.The cubic SiC nanocrystals show different surface charges in water and ethanol solutions due to the interaction of water molecules with polar Si-terminated surfaces of cubic SiC nanocrystals.The results explain the distinctive optical characteristics of colloidal cubic SiC nanocrystals in water and ethanol, and reveal that quantum confinement and surface charges play a great role in determining the optical characteristics of colloidal cubic SiC nanocrystals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Technical Institute of Physics and Chemistry, Chinese Academy of Science, Beijing 100190, PR China. chen.c.x@sjtu.edu.cn.

ABSTRACT
Colloidal cubic silicon carbide (SiC) nanocrystals with an average diameter of 4.4 nm have been fabricated by anisotropic wet chemical etching of microsized cubic SiC powder. Fourier transform infrared spectra show that these cubic SiC nanocrystals contain carboxylic acid, SiH, CH, and CHx groups. UV/Vis absorption and photoluminescence (PL) spectroscopy clearly indicate that water and ethanol colloidal suspensions of the as-fabricated colloidal samples exhibit strong and above band gap blue and blue-green emissions. The cubic SiC nanocrystals show different surface charges in water and ethanol solutions due to the interaction of water molecules with polar Si-terminated surfaces of cubic SiC nanocrystals. The results explain the distinctive optical characteristics of colloidal cubic SiC nanocrystals in water and ethanol, and reveal that quantum confinement and surface charges play a great role in determining the optical characteristics of colloidal cubic SiC nanocrystals.

No MeSH data available.


TEM image of the spherical-like cubic SiC nanocrystals. (a) High-resolution TEM image of 3C-SiC nanocrystals. Insert: magnified image of a single nanocrystal about 4 nm in size. (b) Size distribution of 3C-SiC nanocrystals with the most probable size of 4.4 nm obtained by Gaussian fitting.
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Figure 1: TEM image of the spherical-like cubic SiC nanocrystals. (a) High-resolution TEM image of 3C-SiC nanocrystals. Insert: magnified image of a single nanocrystal about 4 nm in size. (b) Size distribution of 3C-SiC nanocrystals with the most probable size of 4.4 nm obtained by Gaussian fitting.

Mentions: Figure 1a shows a TEM image of the spherical-like cubic SiC nanocrystals with dimensions smaller than 5 nm dispersed on a carbon-coated Cu grid. As one can see, the cubic SiC nanocrystals are highly crystalline and the lattice fringes can be seen, which correspond to the (111), (200), and (220) planes of cubic SiC, respectively. The insert is the magnified image of a single nanocrystal about 4 nm in diameter, and the lattice fringe space is 0.25 nm, which corresponds to (111) plane of bulk cubic SiC. The size distribution of the cubic SiC nanocrystals obtained from the analysis of the TEM images is presented in Figure 1b. A Gaussian fitting indicates that the maximal probability for nanocrystals' diameter is 4.4 nm. The similar etching process for cubic SiC has been investigated, and the suggested reaction could be expressed as follows [16,18]:(1)


Surface charges and optical characteristic of colloidal cubic SiC nanocrystals.

Li Y, Chen C, Li JT, Yang Y, Lin ZM - Nanoscale Res Lett (2011)

TEM image of the spherical-like cubic SiC nanocrystals. (a) High-resolution TEM image of 3C-SiC nanocrystals. Insert: magnified image of a single nanocrystal about 4 nm in size. (b) Size distribution of 3C-SiC nanocrystals with the most probable size of 4.4 nm obtained by Gaussian fitting.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211874&req=5

Figure 1: TEM image of the spherical-like cubic SiC nanocrystals. (a) High-resolution TEM image of 3C-SiC nanocrystals. Insert: magnified image of a single nanocrystal about 4 nm in size. (b) Size distribution of 3C-SiC nanocrystals with the most probable size of 4.4 nm obtained by Gaussian fitting.
Mentions: Figure 1a shows a TEM image of the spherical-like cubic SiC nanocrystals with dimensions smaller than 5 nm dispersed on a carbon-coated Cu grid. As one can see, the cubic SiC nanocrystals are highly crystalline and the lattice fringes can be seen, which correspond to the (111), (200), and (220) planes of cubic SiC, respectively. The insert is the magnified image of a single nanocrystal about 4 nm in diameter, and the lattice fringe space is 0.25 nm, which corresponds to (111) plane of bulk cubic SiC. The size distribution of the cubic SiC nanocrystals obtained from the analysis of the TEM images is presented in Figure 1b. A Gaussian fitting indicates that the maximal probability for nanocrystals' diameter is 4.4 nm. The similar etching process for cubic SiC has been investigated, and the suggested reaction could be expressed as follows [16,18]:(1)

Bottom Line: Fourier transform infrared spectra show that these cubic SiC nanocrystals contain carboxylic acid, SiH, CH, and CHx groups.The cubic SiC nanocrystals show different surface charges in water and ethanol solutions due to the interaction of water molecules with polar Si-terminated surfaces of cubic SiC nanocrystals.The results explain the distinctive optical characteristics of colloidal cubic SiC nanocrystals in water and ethanol, and reveal that quantum confinement and surface charges play a great role in determining the optical characteristics of colloidal cubic SiC nanocrystals.

View Article: PubMed Central - HTML - PubMed

Affiliation: Technical Institute of Physics and Chemistry, Chinese Academy of Science, Beijing 100190, PR China. chen.c.x@sjtu.edu.cn.

ABSTRACT
Colloidal cubic silicon carbide (SiC) nanocrystals with an average diameter of 4.4 nm have been fabricated by anisotropic wet chemical etching of microsized cubic SiC powder. Fourier transform infrared spectra show that these cubic SiC nanocrystals contain carboxylic acid, SiH, CH, and CHx groups. UV/Vis absorption and photoluminescence (PL) spectroscopy clearly indicate that water and ethanol colloidal suspensions of the as-fabricated colloidal samples exhibit strong and above band gap blue and blue-green emissions. The cubic SiC nanocrystals show different surface charges in water and ethanol solutions due to the interaction of water molecules with polar Si-terminated surfaces of cubic SiC nanocrystals. The results explain the distinctive optical characteristics of colloidal cubic SiC nanocrystals in water and ethanol, and reveal that quantum confinement and surface charges play a great role in determining the optical characteristics of colloidal cubic SiC nanocrystals.

No MeSH data available.