Synthesis of alkyl-terminated silicon nanoclusters by a solution route

Journal Article · Wed Jun 09 04:00:00 EDT 1999 · Journal of the American Chemical Society

DOI:https://doi.org/10.1021/ja9828509· OSTI ID:684310

Yang, C S; Bley, R A; Kauzlarich, S M ^[1]; Lee, H W.H.; Delgado, G R ^[2]

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1. Univ. of California, Davis, CA (United States). Dept. of Chemistry
2. Lawrence Livermore National Lab., CA (United States)

The authors describe the synthesis and characterization of alkyl-capped nanocrystalline Si({cflx R}-n-Si) prepared by the reaction of SiCl{sub 4} with Mg{sub 2}Si in ethylene glycol dimethyl ether (glyme) and surface-terminated with various alkyl groups. {cflx R}-n-Si (R = methyl, ethyl, n-butyl, and n-octyl). This reaction produces crystalline nanoparticles with surfaces that can be chemically modified. The resultant crystalline nanoparticles can be suspended in organic solvents or isolated as a powder. The nanoclusters were characterized by transmission electron microscopy (TEM), high-resolution TEM, selected area electron diffraction (SAED), and Fourier transform infrared (FTIR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, UV-vis absorption, and photoluminescence spectroscopy. The average cluster size depends on the reflux time of Mg{sub 2}Si with SiCl{sub 4}, which provided nanoclusters with an average size of 2--5 nm. HRTEM confirms the presence of crystalline nanoclusters, and SAED is consistent with diamond-structured silicon. FTIR spectra are consistent with alkyl surface termination and show very little or no evidence for oxygen on the surface of the nanoclusters, depending on the surface alkyl group. The alkyl termination can be removed by reaction in air at 450 C, and a Si-O stretch is observed in the FTIR spectra. EPR spectroscopy is consistent with crystalline Si nanoclusters and shows no signal at 4 K. The optical absorption spectra show an absorption edge between 260 and 240 nm, depending on the surface alkyl group, while a strong UV-blue photoluminescence between 315 and 520 nm is observed.

• Sponsoring Organization: USDOE Office of Energy Research, Washington, DC (United States); National Science Foundation, Washington, DC (United States)
• DOE Contract Number: AC03-76SF00098; W-7405-ENG-48
• OSTI ID: 684310
• Journal Information: Journal of the American Chemical Society, Journal Name: Journal of the American Chemical Society Journal Issue: 22 Vol. 121; ISSN JACSAT; ISSN 0002-7863
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ALKYL RADICALS
CRYSTALS
ELECTRON SPIN RESONANCE
INFRARED SPECTRA
MAGNESIUM SILICIDES
SILICON
SILICON CHLORIDES
SOLVENTS
SYNTHESIS
TRANSMISSION ELECTRON MICROSCOPY