electrical transport properties in carbon nanotubes

... a growing body of experimental evidence indicating that carbon nanotubes (both MWNT and SWNT) have indeed extraordinary mechanical properties However, the technical difficulties involved in the ... stability limits for rings formed by coiling single wall nanotubes with radii of 0.7 nm (plain line), 1.5 nm (dashed line), and 4.0 nm (dotted line) calculated using a continuum elastic model [45] ... sustain multiple bendings and unbending without any observable permanent damage Bending of MWNTs induces buckling, observed in the form of raised points along the CNT, due to the collapsing of...

Ngày tải lên: 24/03/2014, 05:20

... resistivity and MR response in these polycrystalline manganites are due to both intrinsic effect arising from within the grains and extrinsic effect from intergrain tunneling process across GB Therefore, ... increases gradually with decreasing temperature Spin-polarized intergrain tunneling and spin-dependent scattering at the grain boundaries have been proposed to explain the observed behavior in ... spins, leading to an increase in the intrinsic MR in the Fe-doped sample This is in accordance with the result obtained earlier that the application of magnetic field suppresses ρ2 and ρ5, giving rise...

Ngày tải lên: 16/09/2015, 15:54

... composite sintered at 900 °C is well represented by combination of LSMO and NSMO It can be interpreted as having two phases of LSMO and NSMO coexisting in the composite Upon increasing the sintering ... seen in figure - 4, were attributed to interfacial diffusion across the grain boundaries during sample sintering, in addition to the contribution from non-parallel spin coupling Thus, the interfacial ... spins in the near boundary layers tend to point in the same direction Hence the embedding of LSMO into NSMO particles introduces additional magnetic disorder at the grain boundary layers, leading...

Ngày tải lên: 16/09/2015, 15:54

... ions in SrFeO3 are to be in the HS state with three electrons filling the t2g band, with the remaining eg electron itinerant Apart from that, Chul et al [99] have pointed out convincingly in the ... find the changes in structural composition in relation to the valence state of the Fe ions and at the same time the influence of Fe doping on the magnetic and electrical transport properties in ... enhanced, the dominating Fe3+ in the system still plays a major role in the high resistivity observed in the sample 82 Chapter Three: Influence of Fe doping in Nd0.67Sr0.33MnO3 polycrystalline system...

Ngày tải lên: 16/09/2015, 15:54

... Characterization Techniques Nd2O3 + MnO2 + SrCO3 Mixture and Stirring Target Wet Grinding Sintering Pressing Drying Powder Calcination Grinding YES Single Phase Figure - Flow chart for standard preparation ... Bragg's Law [81]: nλ = 2dsinθ where n is an integer, d is the interplanar spacing in the crystalline phase, θ is the incidence angle and λ is the wavelength of the incident x-ray The diffracted ... annealing in air or oxygen in 1987 Since then, it had been extensively developed for cuprate superconductors and later adapted for manganites In this project, an excimer laser KrF beam operating in...

Ngày tải lên: 16/09/2015, 15:54

... intergrain spin-polarized tunneling Since the electron spin is conserved in the tunneling process, there is an additional magnetic coupling energy when the magnetic moments of the neighboring grains ... RE1-xAExMnO3 manganites as defined in equation (1 – 1) arises from both intrinsic and extrinsic effects Effects intrinsic to a material are distinguished from extrinsic effects which depend on the ... the transfer integral varies as the cosine of the angle between neighboring spins as in equation (1 – 4) As temperature is lowered and spins fluctuation decrease, the combined itinerant/local-moment...

Ngày tải lên: 16/09/2015, 15:54

... CNT samples The red solid line is the least-squares linear fitting line Electrical resistance of the measured CNT sample can be determined from the slope of the fitting line same procedure to ensure ... values of the quality indexes was highest for this sample Interestingly, a further increase in the magnitude of the negative dc bias voltage to -200 V resulted in a slight increase in the IG/ID ratio ... substrates by dip-coating for 10 and drying in N2 The Ti/SiO2/Si-supported catalyst was calcined at 550 °C for 30 (heating rate ) 30 °C/min) to remove the dendrimer, leaving a monolayer of exposed...

Ngày tải lên: 06/05/2014, 08:53

... concept of zone folding, by which Lhe propcrtics of single-walled carbon nanotubes can be directly obtained from the known properties of griiphene Zone folding combined with tight binding allows calculation ... 34 Electmnic Properties of 'Carbon Nanotubes In thc light-binding approximation the Bloch functions @ are written as linear combinations , of the atomic wave functions Instead of using the most ... Constants Bibliography Index Introduction The physics of carbon nanotubes has rapidly evolved into a research field since their discovery by lijima in multiwall for11 1in 1991 and as single-walled tubes...

Ngày tải lên: 04/06/2014, 15:05

... thinking Because of the synthesis impairment, acetylcholine is decreased in the neurons in the Alzheimer disease brain, leading to the incapability of learning, memory, and thinking Providing ... targeting of carbon nanotubes in mice Nat Nanotechnol 2007, 2:47-52 56 Liu Z, Tabakman S, Welsher K, Dai H: Carbon nanotubes in biology and medicine in vitro and in vivo detection, imaging and ... considered for obtaining desired treatment effects The studied ways of CNT administration include oral and injections such as subcutaneous injection, abdominal injection, and intravenous injection There...

Ngày tải lên: 20/06/2014, 22:20

... nanofillers, in particular, nanotubes and graphene sheets, on the thermal conductivity of an uncured liquid epoxy resin There have been considerable interest and effort in the transport properties of carbon ... 81.05.Qk; 81.07.Pr Introduction Due to the increasing importance of energy dissipation in the electronic industry, thermal conductivity of cured epoxy resins has been widely investigated over ... existence of intertube Umklapp scattering processes In addition, SWNTs exhibit a higher number of phonon vibrational modes and a lower defect density in relation to MWNTs, leading to a higher intrinsic...

Ngày tải lên: 20/06/2014, 23:20

... samples were imbedded in KBr disks Elemental analysis (EA) was performed by using a CE Instruments EA1110 The melting points (mp) were determined on a Mel-Temp melting point apparatus and are ... was conducted both in air and nitrogen atmospheres with a heating rate of 10 °C/min using a Perkin–Elmer TGA7 The field emission scanning electron microscopy (FE-SEM) used in this work was a LEO ... without causing the sidewall opening and breaking of the stable crystalline carbon particles This implies that PPA can selectively destroy the amorphous carbons Unlike SWCNTs treated in hydrochloric...

Ngày tải lên: 22/06/2014, 00:20

... sp2bonded carbon atoms in the two-dimensional hexagonal lattice of the graphite layer In addition, the G-band indicates the degree of crystallinity in the graphite structure, whereas the intensity ... Amorphous carbon and carbonaceous particles were decreased and denser vertically aligned MWCNTs were obtained for a higher flow rate pretreatment, as shown in Fig In addition, the MWCNTs shown in Fig ... H2 gas [20] in plasma treatment can provide extra exciting H2 (H*) Therefore, much higher carbon productivity is obtained in the presence of H2 The structure of MWCNTs, which is obtained from the...

Ngày tải lên: 22/06/2014, 01:20

... determined the current-carrying capacity of each wall of DWCNTs by breaking down their wall sequentially under high bias voltages In this paper, we present electrical transport properties of individual ... two-layer resist, and formed by evaporating 15 nm AuPd Devices containing individual metallic DWCNTs with good source and drain contacts were selected for electrical transport measurements The DWCNT ... irregular, having different periodicities in different parts and being asymmetric with VD, which points to a non-ideal Fabry–Perot interference pattern due to minor disorder or inhomogeneity...

Ngày tải lên: 22/06/2014, 01:20

... and highly magnified image as shown in the inset shows that nanotubes remain in their nucleation stage Very short length and low density of nanotubes is observed in sample (Fig 1b) However, for samples ... planes with an inter-planar spacing of *0.34 nm Because of the conical shape, these walls are inclined toward the tube axis making an acute angle of *5–6° in general However, in some 123 28 Nanoscale ... temperature increase, resulting more number of CNTs nucleation and growth CNTs of varying length are observed due to different catalyst particle sizes [33] These samples were examined by TEM for determination...

Ngày tải lên: 22/06/2014, 06:20

... breakdown or arcing during device operation [16, 17] In addition, the electronic resistance between the CNTs and the substrate results in joule heating of the interface This damages the electrical ... by increasing the voltage required for emission over extended periods [17, 18] In order to overcome such undesirable effects, we have fabricated a fully carbon based field emitter by spin coating ... explained in detail in our previous work [21] FT-Raman Spectroscopy studies were carried out on asgrown and purified MWNT, using WiTec GmbH confocal Raman microscope using argon ion laser having...

Ngày tải lên: 22/06/2014, 18:20

... and highly magnified image as shown in the inset shows that nanotubes remain in their nucleation stage Very short length and low density of nanotubes is observed in sample (Fig 1b) However, for samples ... planes with an inter-planar spacing of *0.34 nm Because of the conical shape, these walls are inclined toward the tube axis making an acute angle of *5–6° in general However, in some 123 28 Nanoscale ... temperature increase, resulting more number of CNTs nucleation and growth CNTs of varying length are observed due to different catalyst particle sizes [33] These samples were examined by TEM for determination...

Ngày tải lên: 22/06/2014, 19:20

... 2005) They have introduced a thin capping InxGa1-xAs strainreducing layer (SRL) where the indium composition was increased from 9% to 15% by an interval of 1.5% for the five layers of InAs dots of ... corresponding maximum continuous-wave output power was 0.65mW Spectral broadening using height engineered InAs/GaAs quantum dots Tuning the emission properties of QDs assemblies by in- situ annealing ... immediate analysis shows the spin-orbitals set 38 Fingerprints in the Optical and Transport Properties of Quantum Dots   ( r ) is orthonormal The integrals involving spin-orbitals are solved by...

Ngày tải lên: 26/06/2014, 23:21

... University of Singapore, for kindly providing platinum(IV) compounds, and Prof RAMAPRABHU Sundara, Indian Institute of Technology, Madras, India, for providing ultrapure multi-walled carbon nanotubes ... established a variety of loading strategies, mainly including (a) chemical binding to external surface, (b) π-π stacking on both internal and external surface, (c) encapsulation into inner cavity, etc., ... Chapter Introduction In 2005, Ajima et al first reported the entrapment of CDDP within oxidised singlewalled carbon nanohorns (SWCNHox), finding that the CDDP clusters were maintained inside the...

Ngày tải lên: 08/09/2015, 18:10

... to be quite distinct 1.2 Defects and Dopings in Semiconductors 1.2.1 Intrinsic and Extrinsic Defects in Semiconductors Defining classically, a semiconductor is a material with electrical conductivity ... metallic in nature, making it a possible replacement to tin doped indium oxide (ITO) Adding to that, the Kondo effect has also been observed in the anatase phase of TiO2, making it more interesting ... the CB and the hole in the VB are mobile and can thus induce conductance in the semiconductors In its native state, an intrinsic semiconductor contains defects arising during the various growth...

Ngày tải lên: 09/09/2015, 18:49

... understanding of the underlying physics This is indeed challenging because advances in tailoring thermal property must typically be accompanied by corresponding advances in controlling other properties, ... following subsections, we briefly review the results for low dimensional carbon nanostructures Chapter Introduction 1.1.2 Thermal Transport Properties of Carbon Nanostructures Carbon Nanotubes In ... nonlinear self-energy Σn (τ, τ ′ ) is the key quantity in order to solve the heat transport problem in interacting systems Since exact solution is impossible to obtain technically, certain form...

Ngày tải lên: 10/09/2015, 08:39