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In this paper we report the characterization of linear carbon chains encapsulated in multiwalled carbon nanotubes by using Raman spectroscopy and transmission electron microscopy. The chains are characterized by strong vibrational peaks around 1850cm−1 and both the frequency and intensity of these peaks were found to be dependent on laser excitation energy. Furthermore, resonance Raman spectroscopy...
We first survey the historical aspects of the term Stone–Thrower–Wales (STW) defect and its experimental identification. Physicochemical properties associated with the STW defect have been extensively investigated theoretically as well. However, it is difficult to verify the predicted properties by means of experiments. Here we demonstrate an experimental way to probe the vibrational properties of...
Compositional changes of the residual iron compounds in isothermally treated catalytic chemical vapor deposition derived multi-walled carbon nanotubes have been monitored using 57 Fe transmission Mössbauer spectroscopy and X-ray fluorescence. The iron phases entrapped in the as-synthesized carbon nanotubes consist of γ-iron, α-iron, Fe 3 C and Fe 1−x S. The Fe 1−x S...
This manuscript reports the analysis of the G′ band profile in the Raman spectra of nanographites with different degrees of stacking order. Since the G′ band scattering coming from the 2D and 3D phases coexisting in the same sample can be nicely distinguished, the relative volumes of 3D and 2D graphite phases present in the samples can be estimated from their Raman spectra. The comparison between...
Systematic isothermal annealing has been carried out on catalytic chemical vapor deposition-derived highly disordered multi-walled carbon nanotubes in order to understand the structural evolution of carbon nanotubes kinetically. After specified isothermal time the crystallographic parameters strongly depend on annealing temperature, and can be divided into three stages. Rapid structural enhancement...
The time evolution of graphitization was analyzed based on the structural and magnetic properties of nanodiamond samples annealed at 1600°C for various time intervals. High resolution TEM and XRD show that the nanodiamond particles are converted to spherical onions for short annealing time intervals, and then they are completely transformed to polyhedral nanographite through the annealing for 120min...
Here we describe synthesis of very unusual multi-walled carbon nanotubes through a catalytic chemical vapor deposition method using a floating reactant method and subsequent thermal treatment up to 2600°C in a large quantity. Main characteristics of these nanotubes are (1) relatively wide distribution of diameters ranging from 20 to 70nm and linear, long macro-morphology (aspect ratio >100), (2)...
A nonaqueous electrolyte solution is employed to form double layers on a poly(vinylidene chloride) (PVDC)-based carbon material, thereby extending the application of PVDC-based carbon to nonaqueous systems. Thermal behavior of the Npv-series, which was obtained by simple heat treatment under an inert atmosphere, and the Apv-series, which is obtained by potassium hydroxide (KOH) addition, is confirmed...
Systematic studies of structural changes in stacked cup carbon nanofibers by heat treatment from 1800 to 3000 o C are carried out. The most prominent feature upon heat treatment of these nanofibers is the formation of energetically stable loops between adjacent active end planes both on the inner and outer surfaces. The appearance of the jagged outer and inner surfaces at 3000 o C...
A morphological characterization of activated AR-resin was carried out. The time and temperature effect of the EDLC (electric double layer capacitor) properties of AR-resin were investigated. In order to clarify the relation between the electric double layer capacitance and the ion mobility in the organic solvent, a computer simulation was used to calculate the possible solvation size of Et 4...
Carbon nanofibers with diameters of 80-100 nm were obtained by the pyrolytic method when a benzene solution containing ferrocene was used as a feedstock. A higher flow rate of carrier gas induced variations in the macro-morphology and also in the microstructure. The characteristics of these fibers were bundle formation, such as a macro-fibril, with a different tip morphology as compared with that...
The topological change of the surface of vapor-grown carbon fibers (VGCFs) as a function of heat treatment temperature was observed using FE-SEM, STM and AFM. The morphological change at the micrometre scale from a smooth surface, to a rope-like structure, and to a grain-like structure was closely related with the volume change, especially due to the annular fiber form. The extent to which the micro-domain...
Submicron vapor grown carbon fibers (VGCFs) obtained by a floating growth method were evaluated in terms of their microstructural development with heat treatment temperature (HTT), physical properties of a single fiber and of the bulk state, and additional effects, such as the filler in the electrode of a lead-acid battery and a Li-ion battery system. Its desirable properties, such as relatively high...
Lithium ion secondary batteries are currently the best portable energy storage device for the consumer electronics market. The recent development of the lithium ion secondary batteries has been achieved by the use of selected carbon and graphite materials as an anode. The performance of lithium ion secondary batteries, such as the charge/discharge capacity, voltage profile and cyclic stability, depend...
The structures and anode performance of graphitized and boron-doped milled mesophase pitch-based carbon fibers (mMPCFs) have been comparatively studied and the results obtained by X-ray diffraction (XRD), SEM, Raman spectroscopy and electrochemical measurements are discussed. The boron doping at the level of 2.66 at.% (2.4 wt.%) enhances the growth of the crystallite thickness, L c(002) ,...
The microstructure of milled mesophase pitch-based carbon fibers (mMPCFs) that have been developed as an anode material for Li ion batteries has been studied as a function of heat treatment temperature (HTT) mainly by Raman spectroscopy, and the results obtained are compared with those by X-ray diffraction (XRD) and scanning electron microscopy (SEM) observations. As a functional material, SEM measurements...
Evidence for the formation of an archetypal hemi-toroidal link structure between adjacent concentric walls in pyrolytic carbon nanotubes is presented. The observed and simulated TEM images for such structures are in excellent agreement. This study suggests that double-walled carbon nanotubes, in which the inner and outer tubes are linked by such hemi-toroidal seals, may be one viable way of overcoming...
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