controlled synthesis of carbon nanotubes and their field emission properties

... carbon Results obtained on the generation of carbon monoxide-free hydrogen during the CVD growth process will also be discussed In the present work, we discuss the synthesis of SWNTs, MWNTs and ... preparation of hydride catalysts Figure 2b shows the EDX spectra of Nifilled MWNT TEM and HRTEM images of SWNTs obtained at a growth temperature of 950°C are respectively shown in Fig 3a and b It ... the yield of carbon with the growth temperature has been plotted and shown in Fig It could be seen that the carbon yield increased with increasing growth temperature and a maximum of around 146%...

Ngày tải lên: 22/06/2014, 22:20

Ngày tải lên: 14/11/2014, 12:32

... Shaw EJ, Schlogl R, Hart AJ, Hofmann S, Wardle BL: Nanoscale Zirconia as a Nonmetallic Catalyst for Graphitization of Carbon and Growth of Single- and Multiwall Carbon Nanotubes J Am Chem Soc 2009, ... Page of Figure Energy filtered TEM images of carbon nanotubes produced from phenylboronic acid in a MgO matrix The images show a carbon outer shell and a core (nanowire) comprised B, O and Mg ... decompose the hydrocarbon Reilly and Whitten proposed a free radical condensate (FRC) forms which provides carbon species through a leaving group The breaking of carbon- hydrogen or carbon- carbon bonds...

Ngày tải lên: 21/06/2014, 04:20

... forces of samples S1, S2, and S3 are 67, 146, and 584 Oe, respectively, indicative of soft magnets The remnant magnetizations of samples S1, S2, and S3 at K are determined to be 0.00007, 0.0024, and ... mixture of α-Fe2 O3 , acetylene black, and poly(vinylidene fluoride) with a weight ratio of 80/10/10 The electrolyte was M LiPF6 in a 1:1 mixture of ethylene carbonate/diethyl carbonate, and the ... amount of Na2 SO3 and other kind of inorganic ions were performed Keeping the amounts of FeSO4 and water constant, the molar ratio between FeSO4 and Na2 SO3 varied Fig 3a is the TEM image of the...

Ngày tải lên: 05/05/2014, 15:26

... single wall carbon nanotubes Carbon 2002, 40:2043-2061 24 Deng F, Zheng QS, Wang LF: Effects of anisotropy, aspect ratio, and nonstraightness of carbon nanotubes on thermal conductivity of carbon ... cross-link density and hence, on the final properties of the system Thus, we aimed at studying the effect of two types of carbon- based nanofillers, in particular, nanotubes and graphene sheets, ... mechanical properties with Young's modulus of TPa and ultimate strength of 130 GPa [11] In addition to these outstanding properties, the recent developments on graphene synthesis routes and on -2-...

Ngày tải lên: 20/06/2014, 23:20

... the delivery and redistribution of carbon adatoms between the catalysts and the nanotubes bases were more efficiently controlled than TCVD methods Catalyst poisoning and amorphous carbon formation ... high energy of *100 eV and caused C–C bond breakage The presence of plasma radicals such as NHx and H further chemically etched the surface of the carbon nanotubes The growth mechanism of SWNT in ... indicate the presence of L-bands and confirmed the existence of linear carbon within the SWNT samples Theoretical studies of carbon plasma [68] predicted that using low temperature and power density...

Ngày tải lên: 21/06/2014, 07:20

... 10 s a and b 25 s of exposure to microwave; and c ZnO nanopowder in grams quantity Fig a–d Low and high magnification FESEM images of ZnO nanowires Figure 5a illustrates the morphology of a nanowire ... [24–27] The reduction of the depletion region width as a result of desorption of negative species from ZnO surface was suggested to explain the increase of the excitonic emission of ZnO thin films ... onto the ZnO surface and current decreased to the initial value The decrease of current or recovery is controlled by diffusion and desorption of hydrogen on the surface of nanowires Thus, the...

Ngày tải lên: 22/06/2014, 00:20

... image of IONC-b5 (Inset: SAED ring patterns of IONC-b5); (h) XRD profile of IONC-b5; and (i) VSM profiles of core SPION-7nm (∆) and IONC-b5 (□) (Page 96) Figure 5-3: (a) M(H) curves of SPION-4nm and ... off-resonance frequency Continuous diffusion of protons in and out of the SPIONs’ field of influence results in a partial saturation of the affected volume, depending on the position of the off-resonance ... SPION-7nm, and IONC-b samples (Page 114) Table 5-9: Summary of relaxivity constants of the Ferucarbotran, SPION-7nm, and IONC-b samples (Page 116) Table 6-1: Summary of magnetic properties of MFNs and...

Ngày tải lên: 09/09/2015, 17:55

... Dispersion of carbon nanotubes 1.4 Applications of carbon nanotubes 10 1.5 Structure and morphology of graphene 12 1.6 Properties of graphene 14 1.6.1 Electronic and ... Properties of carbon nanotubes 1.2.1 Electronic and electrical properties 1.2.2 Optical properties 1.2.3 Mechanical properties 1.2.4 Thermal properties ... Figure 6.2 SEM images of (a) GO and (b) Zn-rGO, AFM images of (c) GO and (d) Zn-rGO, (e) TEM image of a free standing Zn-rGO sheet suspended on a lacey carbon TEM grid and (f) selected area electron...

Ngày tải lên: 10/09/2015, 08:35

... Illustration of band structure of inorganic semiconductor as bulk material, nanocrystal and atom (b) Schematic depiction of band diagram of QDs and corresponding electron transition between CB and VB ... nanocrystal and atom (b) Schematic depiction of band diagram of QDs and corresponding electron transition between CB and VB upon excitation 18 The emission of QDs results from the creation and re-combination ... SYNTHESIS OF FUNCTIONAL NANOCOMPOSITES AND THEIR BIO-IMAGING APPLICATIONS SHENG YANG (B Eng., Nanjing Univ of Aeronautics and Astronautics) A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY...

Ngày tải lên: 10/09/2015, 09:30

... migration direction of anion, cation and EOF in a fused silica capillary The magnitude of the EOF depends on the surface concentration of silanol groups and on their degree of dissociation The ... mobilities of the analytes and the properties of the capillary surface hence the EOF rate Also, buffer influences the current produced and amount of Joule heat generated For example, using of potassium ... Schematic representation of migration direction of anion, cation and EOF in a fused silica capillary 24 Fig 1-4 Comparison of flow profiles of chromatography and CE…………………26 Fig 1-5...

Ngày tải lên: 17/09/2015, 17:19

... of PECVD-grown CNTs b TEM image of ALD ZnO-coated CNTs c and d SEM images of ALD ZnO-coated CNTs e TEM image of ALD AlxOy-coated CNTs Fig Raman spectrum of CNTs before (a) and after (b) ALD of ... morphology of the PECVD CNTs prior to deposition Most of the nanotubes are multiwall tubes, and the average diameter of the CNTs is about nm Figure 1b shows the typical TEM image of ALD ZnO-coated ... Raman spectrum of our PECVD MWCNTs (Fig curve a) shows a strong D band, indicating the existence of defects on the tube wall Compared to MWCNTs, the surfaces of the single-walled carbon nanotubes...

Ngày tải lên: 21/06/2014, 08:20

... range of 780–860°C This is of vital importance for their field -emission properties Figure shows the TEM images of samples produced at different temperatures Figure 2a–c are typical TEM images of ... ratio 0.90 0.87 0.92 and the strong band around 1,335 cm-1 is referred to the D-band The D-band corresponds to the defects and disordered in the graphene sheets, and the G-band is attributed to ... well-graphitized carbon nanotubes [31] The intensity ratio of D-band and G-band (ID/IG) were found to be *1 for all the CNTs grown at the three different temperatures, as shown in Table The large ratio of...

Ngày tải lên: 21/06/2014, 18:20

... purity of the MWNT and the presence of the graphitized layer between the nanotubes and carbon paper in Sample C The absence of the graphitized layer between the MWNT and carbon paper in samples B and ... Fig (a) Field emission characteristics of as-grown MWNT spin coated over carbon paper with and without graphitic layer (sample A and sample B) and that of purified MWNT spin coated over carbon ... purpose of this paper is to find out how the field emission properties are influenced by the purity of the MWNT and by the presence of the graphitic layer between the MWNT and the substrate (carbon...

Ngày tải lên: 22/06/2014, 18:20

... mechanical and chemical properties Chapter Introduction Figure1.2 Single-walled and Multi-walled Carbon Nanotubes There are two types of carbon nanotubes: single-walled nanotubes (SWCNTs) and multi-walled ... the temperature and the pressure of operation, the volume and concentration of source gas, the size and the pretreatment of metallic catalyst, and the time of reaction The type of carbon nanotube ... in the controlled fabrication and assembly motivate the author to explore large-scale fabrication of carbon nanotube based structures with controlled parameters and assembly of carbon nanotubes...

Ngày tải lên: 03/10/2015, 21:57

... 3.3 33 Synthesis and characterization of the CdS|CdSe|CdS and CdSe|CdS|CdSe sandwiched nanorods ………………………… 3.2 32 41 Optical properties of the Au-deposited CdS|CdSe|CdS and CdSe|CdS|CdSe sandwiched ... shifted emission would be observed in this type of system because of the small resultant band gap between the lower conduction band and the higher valence band of the two materials present The emission ... Methodologies of Nanocrystals ……………………… 13 1.5.1 Solution Synthesis of Nanocrystals ……………………… 15 1.5.2 Synthesis of Doped Nanocrystals ……………………… 16 1.5.3 Synthesis of Heterostructured and Hybrid...

Ngày tải lên: 03/10/2015, 21:57

... OPTICAL LIMITING AND FIELD EMISSION STUDIES OF CARBON NANOTUBES GOHEL AMARSINH B.Sc (Hons.) SUPERVISOR A/PROF ANDREW WEE THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF PHYSICS NATIONAL ... investigate two of carbon nanotubes most well known properties: optical limiting and field emission Our aim is to modify the carbon nanotubes using physical and chemical means to modify their optical ... Carbon Properties of Carbon Carbon Nanotubes Structure of Carbon Nanotubes Electronic Structure of Carbon Nanotubes Synthesis Methods of Carbon Nanotubes 1.6.1 Arc Discharge 1.6.2 Laser Ablation...

Ngày tải lên: 27/11/2015, 12:23

... Chapter Synthesis and Purification of MultiWalled and Single-Walled Carbon Nanotubes M.Yumura Chapter Electron Diffraction and Microscopy of Carbon Nanotubes S Amelinckx, A Lucas and P ... Structure and Raman Effect of Single-Walled Carbon Nanotubes R Saito, G Dresselhaus and M S Dresselhaus 51 Chapter Behaviour of Single-Walled Carbon Nanotubes in Magnetic Fields H Ajiki and T Ando ... D.M.,King, B E and Wineland, D J., Science, 1996, 272, 1131 2 CHAPTER Synthesis and Purification of Multi-Walled and Single-Walled Carbon Nanotubes MOT00 YUMURA National Institute of Materials and Chemical...

Ngày tải lên: 05/03/2014, 17:20

... 8, 16 and 24 h, respectively, and (d) TiO2 nanotubes (sample S2); (e) HRTEM image of the sample S2 and the inset shows the enlarged picture of the tube wall; (f) HRTEM image of sample S1 and the ... nanostructures of different morphologies such as nanorods, nanowires and nanotubes with different diameters and lengths were formed To understand the formation of the different 1D nanostructures controlled ... to CO2 and was not related to the samples Also a band appears around 453 cmÀ1 for all the samples, which corresponds to a Ti–O band of anatase phase of TiO2 [27,28] The intensity of this band increases...

Ngày tải lên: 20/03/2014, 13:08

... with diameters of 8–25 nm and lengths of several hundred nm Fe film was oxidized during the process and became a-Fe2O3 film with a thickness of 100 nm Figure shows the TEM images of an a-Fe2O3 NW ... density of the NWs per cm2 b Rtotal: the resistance of the total NWs in a unit cm2 Fig A schematic graph of the formation of the a-Fe2O3 NWs in thin and thick iron Fig (a) Schematic illustration and ... resistivity of an a-Fe2O3 NW, and L and r represent the average length (800 nm) and radius (15 nm) of the NW, respectively We assumed that q (4.42 103 Xcm) is a constant for all of the as-produced...

Ngày tải lên: 20/03/2014, 13:08