Growth of few-wall carbon nanotubes with narrow diameter distribution over Fe-Mo-MgO catalyst by methane/acetylene catalytic decomposition

Few-wall carbon nanotubes were synthesized by methane/acetylene decomposition over bimetallic Fe-Mo catalyst with MgO (1:8:40) support at the temperature of 900°C. No calcinations and reduction pretreatments were applied to the catalytic powder. The transmission electron microscopy investigation showed that the synthesized carbon nanotubes [CNTs] have high purity and narrow diameter distribution. Raman spectrum showed that the ratio of G to D band line intensities of IG/ID is approximately 10, and the peaks in the low frequency range were attributed to the radial breathing mode corresponding to the nanotubes of small diameters. Thermogravimetric analysis data indicated no amorphous carbon phases. Experiments conducted at higher gas pressures showed the increase of CNT yield up to 83%. Mössbauer spectroscopy, magnetization measurements, X-ray diffraction, high-resolution transmission electron microscopy, and electron diffraction were employed to evaluate the nature of catalyst particles

Effect of Carbon Overcoat Implantation on the Magnetic and Structural Properties of Perpendicular Recording Media

Carbon overcoats play an important role in the corrosion protection of recording media used in hard disk drive technology. Filtered-cathodic vacuum arc (FCVA) has been studied in the past as a potential technology for depositing media overcoat. In order to achieve the desired property of FCVA carbon, it is essential to apply a suitable bias voltage, which results in an energetic carbon deposition on the magnetic layer of the recording media. In this paper, we focus our attention on the implantation effects of the energetic carbon on the magnetic and the structural properties of the recording media of two types, antiferromagnetically coupled and a single layer, in order to gain a meaningful insight on the implantation and its effect. The studies reveal that the energetic deposition alters the anisotropy constant of the magnetic layer, resulting in a reduction in the coercivity and the thermal stability factor.Accepted versio

Superhydrophobic amorphous carbon/carbon nanotube nanocomposites

Superhydrophobic amorphous carbon/carbon nanotube nanocomposites are fabricated by plasma immersion ion implantation with carbon nanotube forests as a template. The microstructure of the fabricated nanocomposites shows arrays of carbon nanotubes capped with amorphous carbon nanoparticles. Contact angle measurements show that both advancing and receding angles close to 180° can be achieved on the nanocomposites. The fabrication here does not require patterning of carbon nanotubes or deposition of conformal coatings with low surface energy, which are usually involved in conventional approaches for superhydrophobic surfaces. The relationship between the observed superhydrophobicity and the unique microstructure of the nanocomposites is discussed. © 2009 American Institute of Physics

Quantitative, nanoscale mapping of sp2 percentage and crystal orientation in carbon multilayers

Experimental and analytical techniques are introduced for the quantitative, nanoscale mapping of chemical bonding information in carbon-based materials. With these techniques, the spatial orientation of graphitic crystallites in tetrahedrally bonded amorphous carbon was imaged. Simultaneously, the percentage of sp2- and sp3-bonded carbon could be mapped quantitatively, all with spatial resolution of just a few nanometers. Two electron energy-loss spectroscopy (EELS) techniques were compared: low-loss mapping of the plasmon energy and core-loss mapping of the carbon ionization edge. The recently developed EELS acquisition routine of binned gain averaging was applied, together with multivariate statistical analysis, providing a robust method for obtaining real-space, two-dimensional bonding maps

Thermal conductivity of individual multiwalled carbon nanotubes

a b s t r a c t Thermal conductivity of individual multiwalled carbon nanotubes (MWCNT) is measured using a pulsed photothermal reflectance technique. Intrinsic thermal conductivity of individual MWCNT with a diameter 150 nm and length 2 mm at room temperature is extracted to be 2586 W/mK. Individual MWCNT is surrounded by SiO 2 , so parallel resistor model is applied in which SiO 2 supportive is treated as a conducting channel that transports heat in parallel with MWCNT

Study on thermal boundary conductance between diamond and amorphous carbon

International audienc

Structural and wetting properties of metal polymer nanocomposites

Polystyrene thin films of thickness 180 - 200 nm are modified by plasma immersion ion implantation and deposition (PIII&D) technique together with titanium filtered cathodic vacuum arc. The surface structure of modified films turns into a metal polymer nanocomposite where Ti nanoclusters of spatial size 10 - 20 nm are embedded in polystyrene matrices. Such structural formation is the interplay between ion sputtering and ion diffusion effect. The wetting properties of this nanocomposite, such as contact angle aging effect and hysteresis are investigated. The changes in various properties are believed to be due to structure of polymer nanocomposites as well as the basic principles of ion polymer interaction.5 page(s

Structure and wetting properties of metal polymer nanocomposites

Polystyrene thin films of thickness 180-200 nm are modified by plasma immersion ion implantation and deposition (PIII&D) technique together with titanium filtered cathodic vacuum arc. The surface structure of modified films turns into a metal polymer nanocomposite where Ti nanoclusters of spatial size 10-20 nm are embedded in polystyrene matrices. Such structural formation is discussed with the theory of ion-polymer interactions. Furthermore, the wetting properties of this nanocomposite, such as contact angle ageing effect and hysteresis are investigated and compared with Ti deposited polystyrene films.8 page(s