carbon nanotubes i geometrical considerations

... method is studied in detail The elimination of amorphous carbon is also investigated INTRODUCTION The catalytic growth of graphitic carbon nanofibers during the decomposition of hydrocarbons in the ... diagram is depicted in Fig loa, and results in a hexagonal graphene cylinder wall in which the added atoms are arranged in a helical disposition[9,1 I] similar to that observed first by Iijima[l] ... nanotubes in sustaining the arc plasma is their field emission of electrons into the plasma; studying the field emission characteristics of isolated, individual arc-grown nanotubes; and the discovery...

Ngày tải lên: 05/03/2014, 15:21

... method is studied in detail The elimination of amorphous carbon is also investigated INTRODUCTION The catalytic growth of graphitic carbon nanofibers during the decomposition of hydrocarbons in the ... diagram is depicted in Fig loa, and results in a hexagonal graphene cylinder wall in which the added atoms are arranged in a helical disposition[9,1 I] similar to that observed first by Iijima[l] ... nanotubes in sustaining the arc plasma is their field emission of electrons into the plasma; studying the field emission characteristics of isolated, individual arc-grown nanotubes; and the discovery...

Ngày tải lên: 27/06/2014, 17:20

... method is studied in detail The elimination of amorphous carbon is also investigated INTRODUCTION The catalytic growth of graphitic carbon nanofibers during the decomposition of hydrocarbons in the ... diagram is depicted in Fig loa, and results in a hexagonal graphene cylinder wall in which the added atoms are arranged in a helical disposition[9,1 I] similar to that observed first by Iijima[l] ... nanotubes in sustaining the arc plasma is their field emission of electrons into the plasma; studying the field emission characteristics of isolated, individual arc-grown nanotubes; and the discovery...

Ngày tải lên: 27/06/2014, 17:20

... 1(a), while coatings obtained by the dipping technique are shown in Fig 1(b) It is clear the difference in thickness and reflectivity of the TiO2 films obtained by the two deposition methods; in general, ... thickness differences To get additional information about possible factors causing dissimilar sensor response in composite films, the amount of CNT incorporated in the titania matrix was determined ... TiO2 , (4) TiO2 :MWCNT CNT/Multiwall carbon nanotubes; A, anatase; B, brookite; R, rutile Discussion As explained in Section 2, films obtained by dip-coating and screen-printing techniques differ...

Ngày tải lên: 20/03/2014, 13:07

... The FLGs exhibit a ringlike LEED pattern with modulated intensity 64 eV indicated by the dashed circle It evidences a significant distribution of azimuthal disorientation for the first graphene ... peer review Immediate publication on acceptance Open access: articles freely available online High visibility within the field Retaining the copyright to your article Submit your next manuscript at ... techniques LEED and STM experiments show (i) a (3 × 3) SiC surface reconstruction, (ii) a wide distribution of disorientation between the first graphene sheet and the SiC surface, and (iii) rotational...

Ngày tải lên: 21/06/2014, 05:20

... optimized to exhibit much higher ZT values by isotope substitution, isoelectronic impurities, and hydrogen adsorption It is thus reasonable to expect that CNTs may be promising candidates for high-performance ... thermoelectric properties of a series of zigzag and chiral carbon nanotubes which exhibit interesting diameter and chirality dependence Our calculated results indicate that these carbon nanotubes ... single-wall carbon nanotubes calculated within the tight-binding approximation Phys Rev B 2006, 73:085406 34 Zhang G, Li B: Thermal conductivity of nanotubes revisited: effects of Chirality, Isotope...

Ngày tải lên: 21/06/2014, 17:20

... to the interaction from the matrix In the Winkler model, the matrix is considered as an infinite elastic medium In the third part of this study, attention will be paid to the investigation on ... simulations exist; namely ab initio, semi empirical and molecular dynamics methods Density functional theory is an example of an ab initio method while tight binding method is an example of a semi ... (MDS) is a computer simulation technique employed widely in analyzing atomistic systems In MDS, time evolution of a system of atoms is simulated using Newton’s equation of motion Fi = mi d ri dt...

Ngày tải lên: 09/09/2015, 18:54

... orbitals These orbitals can readily mix with each other to optimize the bonding energy of carbon with its neighbors This intermixing of atomic orbitals gives rise to three new Chapter Introduction ... Specifications of the PLD laser system used 123 ix List of Figures List of Figures Fig 1.1 Low magnification SEM image of high density vertically-aligned CNTs Fig 1.2 TEM image of a multiwalled ... Fermi level, Ev is the valence band maximum, V0 donates the original emission barrier height, and V is the barrier height with band bending 24 Fig 3.1 Schematic principles of Bragg's law 43 Fig...

Ngày tải lên: 11/09/2015, 10:17

... 6] F-N equation is built on the basic semiconductor physics such as density of states, Fermi Fermi-Dirac distribution, tunneling phenomenon and tribution, thermionic emission Considering the Wentzel-Kramers-Brillouin ... the Nordheim elliptic functions including image potential corrections For a triangle-shaped potential barrier used in Fowler and Nordheim’s work, this F-N equation can be simplified by using the ... modified in the electronic structures hence leading to significantly promoted FE characteristics [27] By utilizing multilayer ultrathin film structures as FE cold cathode, the effective emission...

Ngày tải lên: 11/09/2015, 10:17

... specimens 3.3 Thin Film Characterization Techniques Characterization techniques of thin films utilized in this project will be briefly introduced in this section, including scanning electron microscopy ... to grow high density vertically-aligned CNTs, which were used as substrate for thin film deposition 3.2 Thin Film Deposition and Preparation Systems This section introduces the principles of ... containing gases or hydrogen gas) are then dissociated within such a discharge Due to the stability and reproducibility of the microwave non-isothermal plasma, film deposition can be carried on...

Ngày tải lên: 11/09/2015, 10:17

... Synthesis of Vertically-Aligned Carbon Nanotubes 4.3.2 Catalytic Growth Mechanism of Carbon Nanotubes Basically, catalytic growth of CNTs is a vapor-solid synthesis process Its mechanism is divided ... magnification top view SEM image in Fig 4.3(a) it can be observed that the CNTs are highly densed on the substrate, confirming a high yield of CNTs by this growth method Under high magnification ... random orientation of CNTs has impeded their application in some areas such as microelectronic devices and field emission In order to obtain vertically-aligned CNTs, one method considered is the growth...

Ngày tải lên: 11/09/2015, 10:18

... [4-6] DLC is applicable in many areas, within which the most prominent application is using it as a coating material to reduce the abrasive wear and extraordinarily increase the lifetime of components ... ta-C film occurs, resulting in the generation of a dipole with an electric field directing toward the film side at the interface This dipole helps reduce the work function of the ultrathin film ... properties are influenced by their surface potential barrier height and width If defining the effective emission potential barrier as the total area of the potential barrier above the Fermi energy,...

Ngày tải lên: 11/09/2015, 10:18

... treatments was increased From the cross-sectional view it is obvious that without hydrogenation treatment, the CNT tips are wrapped with thin films, which look like a layer of whiskers formed with the ... electric field on the emission sites As the ta-C mostly consists of sp3 carbon bonds while CNTs are rich in sp2 bonds, deposition of ta-C onto the CNT surface would result in a decreased conductivity, ... SEM images of the 100 nm ta-C coated composite emitters with and without hydrogen plasma post-treatment as shown in Fig 6.11 High resolution TEM images of the composite emitters with and without...

Ngày tải lên: 11/09/2015, 10:18

... Pristine CNTs 0 Applied electric field, E (V/µm) Fig 6.13 The FE J-E characteristics of the pristine CNTs substrate and the 50 nm ta-C coated composite emitters with varied hydrogenation durations ... (2001) 23 S Dimitrijevic, J C Withers, V P Mammana, O R Monteiro, J W Ager III, and I G Brown, Appl Phy Lett 75, 2680 (1999) 24 R S Gi, T Mizumasa, Y Akiba, Y Hirose, T Kurosu, and M Iida, Jpn J ... bending of the ta-C film in equilibrium with the absorbed water layer in air Evac represents the vacuum level, Ec refers to the conduction band minimum and Ev is the valence band maximum Driven...

Ngày tải lên: 11/09/2015, 10:18

... characteristics of pristine field emitters, the following approaches could be employed: (1) Lower the effective potential emission barrier either by decreasing the barrier height or reducing the barrier ... most promising candidates in FE application due to its excellent properties such as negative electron affinity, hardness and thermal conductivity, as well as chemical stability [1-3] It is speculated ... List of Publications List of Publications Journal papers with main contribution J Yu, Y M Foong, A T T Koh, and Daniel H C Chua “Hydrogenation and its effects on the field emission characteristics...

Ngày tải lên: 11/09/2015, 10:18

... SV, Grigorieva IV, Firsov AA: Electric field effect in atomically thin carbon films Science 2004, 306:666-669 Novoselov KS, Geim AK, Morozov SV, Jiang D, Katsnelson MI, Grigorieva IV, Firsov ... results can be attributed to the differences in the media surrounding the nanoparticles when the resin is in the liquid or solid state While the FGS are dispersed in a liquid media, they are not ... nanocomposite preparation, participated in the discussion, and revised the manuscript MK supervised the thermal conductivity measurements and revised the manuscript providing important intellectual...

Ngày tải lên: 20/06/2014, 23:20

... using the tight-binding model In addition to isolated individual carbon nanotubes, condensed phases of nanotubes, i. e., bundles of single-walled carbon nanotubes and concentric multiwalled carbon ... single nanotube For the imaging of individual nanotubes, either MWNTs or SWNTs, transmission electron microscopy (TEM) is king Indeed, it is probably fair to say that without TEM, nanotubes might ... characteristics, it is difficult if not impossible to reliably incorporate those nanotubes into a conventional chip-based device platform A goal for nanotube device experiments is to incorporate nanotubes...

Ngày tải lên: 04/06/2014, 14:43

... facilitated its biodistribution in tissues, and SWCNTs was completely redirected from tissue with intrinsic affinity (thyroid) to lungs In this experiment, Na12 5I- filled glyco-SWCNTs were intravenously ... from: Convenient online submission Rigorous peer review Immediate publication on acceptance Open access: articles freely available online High visibility within the field Retaining the copyright to ... described approaches, functionalization has been the most effective approach In addition, functionalization has been shown capable of decreasing cytotoxicity, improving biocompatibility, and giving...

Ngày tải lên: 20/06/2014, 22:20

... state of dispersion, could be achieved In addition, the chemical modification of SWCNTs, which is able to diminish lateral interaction between SWCNTs and also to improve chemical affinity between ... with additional amount of phosphorous pentoxide (P2O5) medium was optimized condition for ‘‘direct’’ Friedel–Crafts acylation reaction using a carboxylic acid instead of the corresponding acid ... residues Its viscous nature would help to impede reaggregation of SWCNTs after their dispersion The reaction condition in PPA/P2O5 medium at 130 °C has been utilized in both the polymerization...

Ngày tải lên: 22/06/2014, 00:20