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Novel SiOx-coated carbon nanotubes
M.Ruhle,T.Seeger,Ph.Redlich,N.Grobertb,M.Terrones,D.R.M.Walton,H.W.Kroto 한양대학교 세라믹연구소 2002 Journal of Ceramic Processing Research Vol.3 No.1
A room temperature colloidal method for coating carbon nanotubes with silicon oxide is described. Morphology, chemical composition and SiOx/C interfaces of the coatings were investigated using state-of-the-art transmission electron microscopy and high spatially resolved electron energy-loss spectroscopy. The amorphous SiOx coatings exhibit a thickness of up to 10 nm. In addition, coatings were also created by a high temperature route. However, they tend to be more unstable and spallate when compared to coatings deposited at room temperature.
Kang, C.S.,Fujisawa, K.,Ko, Y.I.,Muramatsu, H.,Hayashi, T.,Endo, M.,Kim, H.J.,Lim, D.,Kim, J.H.,Jung, Y.C.,Terrones, M.,Dresselhaus, M.S.,Kim, Y.A. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.107 No.-
<P>Linear carbon chains (LCCs) consisting of sp-hybridized carbon atoms are considered a fascinating 1D system and could be used in the fabrication of the next-generation molecular devices because of its ideal linear atomic nature. A large portion of long LCCs inside multi-walled carbon nanotubes (MWCNTs) were synthesized by atmospheric arc discharge in the presence of boron. Closed-end growth of MWCNTs in the arc process is suggested as a critical condition for the simultaneous growth of LCCs within the inner cores of carbon nanotubes. The strong Raman line around 1850 cm(-1) was used to characterize the degree of filling as well as their structural stability under high temperature thermal treatments. We observed a distinctive change in the electrical conductivity of the MWCNT assembly before and after the disappearance of LCCs due to the expected strong coupling interaction between the LCCs and the innermost tube. This work demonstrates for the first time the enhanced effect of confined linear carbon chains on the overall electrical conductivity of MWCNT assemblies. (C) 2016 Elsevier Ltd. All rights reserved.</P>
Zhao, W.,Shan, C.,Elias, A.L.,Rajukumar, L.P.,O'Brien, D.J.,Terrones, M.,Wei, B.,Suhr, J.,Lu, X.L. Pergamon Press ; Elsevier Science Ltd 2015 Carbon Vol.95 No.-
To expand the applications of carbon nanotubes (CNTs) at macroscale, a heteroatom doping technique has been employed to fabricate isotropic 3-D CNT architectures by inducing elbow-like covalent junctions into multiwalled CNTs. As the junctions modify the topology of each CNT by favoring the stable bends in CNTs, junction stiffness and the consequence of junction-related morphology changes in sponge's hyperelasticity remain largely elusive. In this study, two types of 3-D multiwalled CNT sponges were fabricated by inducing boron-doped or nitrogen-doped covalent junctions into CNTs. Hyperelastic properties of the sponges were experimentally quantified as the functions of CNT morphology. A novel microstructure informed continuum constitutive law was developed specifically for such isotropic CNT sponges with junctions. Analyzing the experimental data with the new theory demonstrated that, for the first time, the effective modulus of boron-doped junctions (~100 GPa) is higher than that of nitrogen-doped junctions (~20 GPa), and the junction stiffness is a key factor in regulating the hyperelastic compressive modulus of the material. Theoretical analysis further revealed that increased number of junctions and shorter segments on each individual CNT chain would result in stronger hyperelastic 3-D CNT networks. This study has established a fundamental knowledge base to provide guidance for the future design and fabrication of 3-D CNT macrostructures.
Alencar, R. S.,Aguiar, A. L.,Paschoal, A. R.,Freire, P. T. C.,Kim, Y. A.,Muramatsu, H.,Endo, M.,Terrones, H.,Terrones, M.,San-Miguel, A.,Dresselhaus, M. S.,Souza Filho, A. G. American Chemical Society 2014 The Journal of Physical Chemistry Part C Vol.118 No.15
<P>The dependence of the radial breathing modes (RBMs) and the tangential mode (G-band) of triple-wall carbon nanotubes (TWCNTs) under hydrostatic pressure is reported. Pressure screening effects are observed for the innermost tubes of TWCNTs similar to what has been already found for DWCNTs. However, using the RBM pressure coefficients in conjunction with the histogram of the diameter distribution, we were able to separate the RBM Raman contribution related to the intermediate tubes of TWCNTs from that related to the inner tubes of DWCNTs. By combining Raman spectroscopy and high-pressure measurements, it was possible to identify these two categories of inner tubes even if the two tubes exhibit the same diameters because their pressure response is different. Furthermore, it was possible to observe similar RBM profiles for the innermost tubes of TWCNTs using different resonance laser energies but also under different pressure conditions. This is attributed to changes in the electronic transition energies caused by small pressure-induced deformations. By using Raman spectroscopy, it was possible to estimate the displacement of the optical energy levels with pressure.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2014/jpccck.2014.118.issue-15/jp4126045/production/images/medium/jp-2013-126045_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp4126045'>ACS Electronic Supporting Info</A></P>
Fujisawa, K.,Ka, I.,Le Borgne, V.,Kang, C.S.,Kobayashi, K.,Muramatsu, H.,Hayashi, T.,Kim, Y.A.,Endo, M.,Terrones, M.,El Khakani, M.A. Pergamon Press ; Elsevier Science Ltd 2016 Carbon Vol.96 No.-
<P>Carbon nanotubes (CNTs)/lead sulfide (PbS) quantum dots (QDs) nanohybrids have been synthesized through the controlled decoration of CNTs by PbS-QDs by means of the pulsed laser deposition technique. The size of the PbS-QDs and their surface coverage of the CNTs' surface are monitored through the number of laser ablation pulses. Here, while comparing both single-walled (SW) and double-walled (DW) CNTs based nanohybrids, focus is put on the investigation of their interfacial structure and the effect of inner tube. Anchoring PbS through direct sulfur-carbon chemical bonding between CNTs' outer wall and PbS-QDs, which are thought to be profitable for efficient charge transfer but not for charge transport along CNT's tube axis, are confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy. In the case of double-walled CNTs (DWCNTs), inner tube remains unaffected by ablated PbS species, then it serves efficient conduction way for transferred photo-generated charges. This unique feature of the DWCNTs based nanohybrid, where the photocharges are generated by the chemically bonded PbS-QDs to the outer tube and then efficiently conveyed by the inner tube of the nanotubes, is highly likely at the origin of their significantly higher photo-activity (several hundred times than in SWCNTs-based nanohybrids). (C) 2015 Elsevier Ltd. All rights reserved.</P>