کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10611353 | 986061 | 2005 | 9 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Synthesis and Raman characterization of boron-doped single-walled carbon nanotubes
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
مهندسی انرژی
انرژی (عمومی)
پیش نمایش صفحه اول مقاله
چکیده انگلیسی
A systematic study was carried out to dope single-walled carbon nanotube (SWNT) bundles with varying amounts of boron using the pulsed laser vaporization technique. Targets containing boron concentrations ranging from 0.5 to 10Â at.% boron were prepared by mixing elemental boron with carbon paste and the Co/Ni catalysts. The laser-generated products that were obtained from these targets were characterized by high resolution transmission electron microscopy, electron energy loss spectroscopy (EELS), thermoelectric power (TEP) measurements, and Raman scattering experiments. Electron microscopy and Raman studies revealed that the presence of various levels of boron concentration in the target strongly affected the products that were prepared. SWNTs were found in the products prepared from targets containing up through 3Â at.% boron, and high resolution EELS estimated that less than 0.05-0.1Â at.% boron is present in the SWNT lattice. The absence of SWNT bundles in the products derived from targets containing more than 3Â at.% boron implies that the presence of excess boron in the carbon plume severely inhibits the carbon nanotube growth. The overall effect of the boron incorporation primarily leads to: (i) a systematic increase in intensity of the disorder-induced band (D-band) upon boron doping, with increasing D-band intensity observed for higher doping levels, (ii) a systematic downshift in the Gâ²-band frequency due the relatively weaker C-B bond, and (iii) a non-linear variation in the RBM and Gâ²-band intensities which is attributed to shifts in resonance conditions in the doped tubes. Resonant Raman spectroscopy thus provides large changes in the intensity of prominent features even when the dopant concentration is below the detectable limit of EELS (0.05-0.1Â at.%). Thermoelectric power data also provide complementary evidence for the presence of a small boron concentration in the SWNT lattice which transforms the SWNTs into a permanently p-type material.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Carbon - Volume 43, Issue 2, 2005, Pages 219-227
Journal: Carbon - Volume 43, Issue 2, 2005, Pages 219-227
نویسندگان
K. McGuire, N. Gothard, P.L. Gai, M.S. Dresselhaus, G. Sumanasekera, A.M. Rao,