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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.


Surface chemistry of 3C-SiC nanocrystals. Surface chemistry of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water.
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Figure 5: Surface chemistry of 3C-SiC nanocrystals. Surface chemistry of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water.

Mentions: The surface acts as the electron acceptor in the process (3) and hole acceptor in process (4). In the ethanol suspension, only -H groups are dissociated. Therefore, only C-H and Si-H groups are formed on the surface of colloidal cubic SiC nanocrystals. The surface charges of cubic SiC nanocrystals dispersed in ethanol and water suspensions are schematically represented in Figure 5. As reported by Wu et al. [30], the quantum confinement and Si-OH surface terminations may be the origin of the blue-green PL emission of water suspension.


Surface charges and optical characteristic of colloidal cubic SiC nanocrystals.

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

Surface chemistry of 3C-SiC nanocrystals. Surface chemistry of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Surface chemistry of 3C-SiC nanocrystals. Surface chemistry of 3C-SiC nanocrystals dispersed in (a) ethanol and (b) water.
Mentions: The surface acts as the electron acceptor in the process (3) and hole acceptor in process (4). In the ethanol suspension, only -H groups are dissociated. Therefore, only C-H and Si-H groups are formed on the surface of colloidal cubic SiC nanocrystals. The surface charges of cubic SiC nanocrystals dispersed in ethanol and water suspensions are schematically represented in Figure 5. As reported by Wu et al. [30], the quantum confinement and Si-OH surface terminations may be the origin of the blue-green PL emission of water suspension.

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.