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Carbon films were prepared from polyimide films (Kapton and Upilex-s with thickness of 50μm) by heat treatment at 750°C under Ar atmosphere. The electrical resistance of the carbon films was remarkably increased with the adsorption of acetone and decreased with its desorption. The magnitude of the resistance change increased with increasing vapor pressure of acetone and with decreasing temperature...
Foamed and solid polypropylene/carbon fiber (PP–CF) composites containing various CF contents (0–10vol.%) were injection-molded. Foamed composites were achieved using dissolved pressurized nitrogen gas. The effects of foaming on the fibers inter-connectivity and orientation, electrical percolation threshold, through-plane electrical conductivity, longitudinal and transversal in-plane conductivities,...
The spin-polarized electronic properties for a zigzag-edge graphene nanoribbon (ZGNR) with an extended line defect are investigated, particularly focusing on controlling the effects of an external transverse electric field (E ext ). An ab initio scanning tunneling microscope image for the defective ZGNR is also predicted. Results show that such a ZGNR can exhibit a strong spin polarization...
X-ray tomography was used to reconstruct the microstructure of a carbon/carbon (C/C) composite to clearly reveal cracks and voids. The voids are divided into two categories (bubbles and micro-pores), and the cracks are classified into three categories (matrix, intra-bundle, and interfacial). The bubbles were found to account for 2–3% volume in the composite and intra-bundle porosity was in the range...
The small-angle X-ray scattering measurements during tensile deformation have been performed for studying the structure and mechanical property relationships of twisted carbon nanotube (CNT) yarns. The tensile strength distribution and the diameter changes during tensile deformation have also been measured. The orientation distribution of the CNTs in the yarn has been determined and its changes during...
High-quality boron-doped diamonds were synthesized from four boron-doped carbon sources with different boron concentration using a static high-pressure process with metal solvent. Three diamond pellets obtained from the carbon sources with boron concentrations less than the solubility limit showed a homogeneous appearance and obvious X-ray diffraction patterns characteristic of diamond. The electrically-conducting...
Unstable characteristics of graphene field effect transistors (FETs) have generated concerns about the feasibility of graphene electronic devices. Two dominant mechanisms of instability, charge trapping and interfacial redox reaction, and their quantitative contributions were investigated for chemical vapor deposited graphene by analyzing the transient responses of the hysteretic characteristics in...
This paper presents the development of an analysis technique and software program to quantify the anisotropy of pyrolytic carbon or ultra-fine grain graphite using selected area electron diffraction (SAED) patterns from a transmission electron microscope. Results serve as input to a computer program that calculates the Bacon anisotropy factor (BAF) and orientation parameter (R). This was achieved...
The effect of acidic functional groups on an activated carbon surface on the adsorption of benzene, phenol and nitrobenzene was examined. Adsorption experiments for these aromatics in aqueous solution were conducted using two types of activated carbon with large and small amounts of surface functional groups, DAOx and DAOxOG, respectively, to obtain the adsorption isotherms. Adsorption kinetics of...
A theoretical model is presented that explains spontaneous changes in the crystalline orientation of nanoparticles. The spontaneous changes in crystalline orientation are attributed to the crystal anisotropy of the surface energy of nanocrystalline particles. We consider an important specific case of the chemical vapor deposition growth of carbon nanofibers, where previous studies have shown that...
It is known that carbon materials catalyze hydrogen peroxide decomposition in aqueous media. However, the catalytic activity of a particular carbon is dependent on various coupled structural, textural and chemical characteristics of the material, such that, formerly, the prediction of activity has not been possible. Here, the application of cyclic voltammetry (CV) is introduced as a rapid and conclusive...
We demonstrate the effect of mechanical strain on the electrostrictive behavior of catalytically grown cellular structure of carbon nanotube (CNT). In the small strain regime, where the stress–strain behavior of the material is linear, application of an electric-field along the mechanical loading direction induces an instantaneous increase in the stress and causes an increase in the apparent Young’s...
This paper demonstrates all-carbon photovoltaic devices made of amorphous carbon (a-C) and C 60 thin films. C 60 film is deposited by the sublimation in vacuum and a-C film is synthesized by exposing N 2 radicals to C 60 during the deposition. C 60 is converted into a-C when the rf power is larger than 150W and the optical band gap decreases with increasing...
N-doped graphene (NG) has been prepared by annealing reduced graphene oxide (RGO) in ammonia. The magnetic properties of RGO and NG have been studied. The results showed that doping RGO with N at a relatively low temperature (⩽600°C) can increase its magnetization, and which can be increased by 64.1% at the annealing temperature of 500°C.
Ultrananocrystalline diamond (UNCD) films were prepared by microwave plasma chemical vapor deposition using argon-rich CH 4 /H 2 /Ar plasmas with different H 2 concentrations from 5% to 20%. The influence of the H 2 concentration on the microstructure, morphology and phase composition of the UNCD films was investigated by SEM, XRD, surface profilometry and Raman spectroscopy...
Carbon foams (CFoams) were made by combining a hard template with a catalytic graphitization method, in which polyurethane foam is used as a sacrificial template, polyamic acid is used as carbon source and Ni is used as catalyst. The cell walls of CFoams are made of in situ self-assembled carbon nanocapsules (CNCs) with diameters of 30–80nm. The open cells of the CFoams are, on average, 500μm in diameter,...
Commercially available phenol-based carbon nanofibers (CNFs) and activated carbon nanofibers (ACNFs) about 200–500nm in diameter were heated to 900°C and then heat-treated further at temperatures of 3000–3200°C. The texture and structure of the both heat-treated samples were investigated by SEM and TEM observations and measurements of XRD and Raman spectra. A large number of fine graphite particles...
Polyethylene was crystallized on carbon nanotubes (CNTs) resulting in the formation of nanosheets on the surface. The material was then carbonized in sulfuric acid at 20°C for 24h, resulting in a carbon shish-kebab (CSK) structure. Incorporating the CSKs in polyimide (PI) matrix produced a uniform dispersion in which interactions between the nodules producing an interlocking effect that significantly...
An easy one-pot polylol approach has been reported on the preparation of graphene decorated with magnetic Fe 3 O 4 nanoparticles for immobilizing porcine pancreatic lipase. The microstructures and interaction of the hybrids were characterized by several methods, which indicated that the Fe 3 O 4 nanoparticles are chemically bonded onto graphene sheets with tunable size...
Coal tar pitch (CTP) was modified either with 10g cinnamaldehyde (CMA) per 100g CTP, 7g p-toluene sulfonic acid (PTS) per 100g CTP, or a mixture of 10g CMA and 7g PTS per 100g CTP. The parent CTP and the modified CTPs were characterized by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis. The four samples were carbonized at different temperatures and the products were...
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