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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.


PL emission spectra of the colloidal cubic SiC nanocrystals. Room temperature PL spectra of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water. (c) The PL emission spectra of colloidal cubic SiC nanocrystals in water and ethanol solutions at the excitation wavelength of 320 nm (the insert is two emission photos taken using a Canon digital camera at the same excitation wavelength).
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Figure 4: PL emission spectra of the colloidal cubic SiC nanocrystals. Room temperature PL spectra of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water. (c) The PL emission spectra of colloidal cubic SiC nanocrystals in water and ethanol solutions at the excitation wavelength of 320 nm (the insert is two emission photos taken using a Canon digital camera at the same excitation wavelength).

Mentions: Figure 4a, b depicts the typical PL emission spectra of the colloidal cubic SiC nanocrystals in water and ethanol, which exhibit prominent above band gap blue and blue-green emissions at different excitation wavelengths. As the excitation wavelength increases, the emission peak shows a monotonic red shift. Figure 4c shows the PL emission spectra of colloidal cubic SiC nanocrystals in water and ethanol solutions at the excitation wavelength of 320 nm. As we can see, the full width at half maximum (FWHM) of PL spectra are 127 and 67 nm, respectively. The observed phenomenon can be explained by the solubility of the cubic SiC nanocrystals in water and ethanol. The number of cubic SiC nanocrystals steadily dispersed in ethanol is smaller than that in water, which leads to a narrower FWHM. The insert of Figure 4c is two emission photos taken using a Canon digital camera at the same excitation wavelength. The emission spots are seen to be blue and blue-green, respectively. These results are in good agreement with the previous reports [30].


Surface charges and optical characteristic of colloidal cubic SiC nanocrystals.

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

PL emission spectra of the colloidal cubic SiC nanocrystals. Room temperature PL spectra of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water. (c) The PL emission spectra of colloidal cubic SiC nanocrystals in water and ethanol solutions at the excitation wavelength of 320 nm (the insert is two emission photos taken using a Canon digital camera at the same excitation wavelength).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 4: PL emission spectra of the colloidal cubic SiC nanocrystals. Room temperature PL spectra of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water. (c) The PL emission spectra of colloidal cubic SiC nanocrystals in water and ethanol solutions at the excitation wavelength of 320 nm (the insert is two emission photos taken using a Canon digital camera at the same excitation wavelength).
Mentions: Figure 4a, b depicts the typical PL emission spectra of the colloidal cubic SiC nanocrystals in water and ethanol, which exhibit prominent above band gap blue and blue-green emissions at different excitation wavelengths. As the excitation wavelength increases, the emission peak shows a monotonic red shift. Figure 4c shows the PL emission spectra of colloidal cubic SiC nanocrystals in water and ethanol solutions at the excitation wavelength of 320 nm. As we can see, the full width at half maximum (FWHM) of PL spectra are 127 and 67 nm, respectively. The observed phenomenon can be explained by the solubility of the cubic SiC nanocrystals in water and ethanol. The number of cubic SiC nanocrystals steadily dispersed in ethanol is smaller than that in water, which leads to a narrower FWHM. The insert of Figure 4c is two emission photos taken using a Canon digital camera at the same excitation wavelength. The emission spots are seen to be blue and blue-green, respectively. These results are in good agreement with the previous reports [30].

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.