http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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>
Multivalency-Induced Band Gap Opening at MoS<sub>2</sub> Edges
Lucking, Michael C.,Bang, Junhyeok,Terrones, Humberto,Sun, Yi-Yang,Zhang, Shengbai American Chemical Society 2015 Chemistry of materials Vol.27 No.9
<P>Zigzag edges of monolayer MoS<SUB>2</SUB> and other transition-metal (TM) dichalcogenides are experimentally shown to exhibit strong photoluminescence. Atomic models that have been proposed for these edges, however, are all metallic. Here, we address this puzzle by using first-principles calculations. We found that a more generic electron counting model (ECM) can be developed, which, when coupled with the ability of TM atoms at edges to change their valency from 4+ to 5+, can quantitatively account for the band gap opening at the zigzag edges. Due to the ECM, a 3× periodicity along the zigzag edge is necessary to open the band gap. Moreover, consistent with experiment, oxygen adsorption is shown to open even larger band gaps than intrinsic edges.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2015/cmatex.2015.27.issue-9/acs.chemmater.5b00398/production/images/medium/cm-2015-003989_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm5b00398'>ACS Electronic Supporting Info</A></P>
Fujisawa, Kazunori,Hayashi, Takuya,Endo, Morinobu,Terrones, Mauricio,Kim, Jin Hee,Kim, Yoong Ahm The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.26
<P>We explored the effect of substitutional boron doping on the electrical conductivity of a metallicity-separated single walled carbon nanotube (SWCNT) assembly. Boron atoms were introduced into semiconducting (S)- and metallic (M)-SWCNT assemblies using high temperature thermal diffusion and the concentration of the doped boron atoms was controlled by the thermal treatment temperature. Depending on the conduction mechanism of the SWCNT assembly, both positive and negative effects upon boron incorporation are observed. For the S-SWCNT sheet, the electrical resistivity decreased by about 1 order on introduction of a small amount of boron atoms, due to the localized state for hopping conduction. In contrast, we observed an increase in the electrical resistivity on boron doping for M-SWCNTs. The pristine and boron doped metallic SWCNTs exhibited a tendency of decreasing electrical resistivity in the presence of an external magnetic field perpendicular to the film, which indicated two-dimensional weak localization behavior. A detailed analysis of the resistivity and the magnetoresistance implied that an increase in the inelastic scattering event at the doped boron site reduced the phase coherence length, leading to an increase in the electrical resistivity.</P>
Double-walled carbon nanotubes: synthesis, structural characterization, and application
Kim, Yoong Ahm,Yang, Kap-Seung,Muramatsu, Hiroyuki,Hayashi, Takuya,Endo, Morinobu,Terrones, Mauricio,Dresselhaus, Mildred S. 한국탄소학회 2014 Carbon Letters Vol.15 No.2
Double walled carbon nanotubes (DWCNTs) are considered an ideal model for studying the coupling interactions between different concentric shells in multi-walled CNTs. Due to their intrinsic coaxial structures they are mechanically, thermally, and structurally more stable than single walled CNTs. Geometrically, owing to the buffer-like function of the outer tubes in DWCNTs, the inner tubes exhibit exciting transport and optical properties that lend them promise in the fabrication of field-effect transistors, stable field emitters, and lithium ion batteries. In addition, by utilizing the outer tube chemistry, DWCNTs can be useful for anchoring semiconducting quantum dots and also as effective multifunctional fillers in producing tough, conductive transparent polymer films. The inner tubes meanwhile preserve their excitonic transitions. This article reviews the synthesis of DWCNTs, their electronic structure, transport, and mechanical properties, and their potential uses.
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.
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.
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>