S. Al-Heniti

Adsorption sites of hydrogen atom on pure and Mg-doped multi-walled carbon nanotubes

Hydrogen adsorption sites on pure multiwalled carbon nanotube (MWCNT) and Mg-doped MWCNTs material system have been investigated using molecular dynamics (MD) simulations as well as quantum chemical calculations. Through combining MWCNTs with Mg, the hydrogen adsorption sites energy on this Mg-MWCNTs system is found to be larger than that of the pure MWCNTs. Additionally, it was found that, through Mg-doping, new adsorption sites for hydrogen molecules are created in comparison with undoped nanotubes. It is also found that H atom is preferably adsorbed at every place near magnesium atom.

A novel conducting nanocomposites containing phenolic resin/carbon nanoparticles for electromagnetic wave shielding effectiveness at microwave frequency

The microstructure of phenolic resin reinforced carbon black (CB) nanoparticles was examined by scanning electron microscopy. The thermal stability of the nanocomposites was examined by means of isothermal resistivity change at 100°C. Electromagnetic interference (EMI) response of conducting phenolic/CB nanocomposites in the frequency range from 1 GHz to 12 GHz has been studied. In the microwave range from 8 to 12 GHz conducting nanocomposites shows a shielding effectiveness in the range 30-40 dB. The highest EMI of nanocomposites was 55 dB for CB12 sample which is realistic for an industrial application. The results of this study demonstrate the high possibility of using the proposed nanocomposites as electronic conductive fillers in polymer package and EMI shielding effectiveness at microwave frequency.

Influence of aluminium concentration in Zn0:9V0:1O nanoparticles on structural and optical properties

Abstract The (V,Al) co-doped ZnO nano-structured powders (Zn0.9-xV0.1AlxO, where x = 0.02, 0.03 and 0.04) were synthesized via the sol-gel technique and their structural and optical properties were investigated. The effect of Al concentration on the structural and optical properties of the Zn0.9-xV0.1AlxO nanopowders was studied using various techniques. The XRD patterns indicate that the samples have a polycrystalline wurtzite structure. The crystallite size increases with increasing the Al content and lies in the range of 23 to 30 nm. The lattice strain, estimated by the Stokes-Wilson equation, decreases when Al content increases. SEM and TEM micrographs show that Zn0.9-xV0.1AlxO powders are the agglomeration of nanoparticles having spherical and hexagonal shapes with dimensions ranging from 20 to 30 nm. FT-IR spectra show a distinct absorption peak at about 500 cm-1 for ZnO stretching modes and other peaks related to OH and H2O bands. Raman spectra confirm the wurtzite structure of the Zn0.9-xV0.1AlxO nanoparticles. The direct band gaps of the synthesized Zn0.9-xV0.1AlxO nanopowders, estimated from the Brus equation and the crystallite sizes deduced from XRD, are around 3.308 eV. The decomposition process of the dried gel system was investigated by thermal gravimetric analysis (TGA).

Synthesis and characterisation of tin dioxide nanoparticles and effect of annealing temperature

Nanopowder of SnO2 was successfully synthesised by the chemical co-precipitation technique. The product sample was characterised by transmission electron microscope (TEM), X-ray diffraction (XRD) and UV-visible absorption spectrum. Analysis shows that the nanomaterial is found to be phase-pure and nanocrystalline, with a mean particle size around 50 nm. The maximum absorption is observed at around 320 nm. Effect of different annealing temperature on the particle size and shape are also studied. There is no change in the shape and size of these nanoparticles, while annealing them at temperatures ranging from 300°C-600°C. This suggests that the prepared nanoparticles might be useful as gas sensors at hot environments.

Synthesis and characterisation of amorphous SeTe nanorods prepared by ball milling

The amorphous Se97Te3 nanorods were prepared by mechanical milling. The amorphous Se97Te3 materials were used as a starting material. The milled materials were characterisation by XRD, TEM and optical measurement by JASCO, UV/VIS/NIR spectrophotometer in a wavelength region 300 nm-1000 nm. The experimental result shows that an amorphous stage is also achieved during the milling process. TEM analysis showed that after 50 hours of milling time, multi-walled amorphous nanorods were formed with a diameter of about 90 nm and after 60 hours of milling time amorphous nanowires of about 80 nm diameter was formed. The optical absorption measurement indicates that the absorption mechanism is due to indirect transition. It has been observed that the absorption coefficient increases lineally with the increase in photon energy and the optical band gap increases with the increase of milling time.

Synthesis and characterisation of ZnO structures containing the nanoscale regime

Synthesis of ZnO nanorods assembled in flower-shaped spherical morphologies have been grown via solution process by using zinc nitrate hexahydrate (Zn(NO3)2. 6H2O) and sodium hydroxide (NaOH) at low-temperature of 100°C in eight hours. The grown ZnO structures were characterised in terms of their structural and optical properties. The detailed structural characterisations demonstrated that the synthesised products are single crystalline with the wurtzite hexagonal phase and grown along the [0001], c-axis direction. A strong absorption band at 480 cm−1 was observed in Fourier transform infra red (FTIR) spectrum which was related with the ZnO. The optical property of the grown ZnO structures was observed by using UV-visible studies. Only a sharp peak at 371 nm was observed in the UV-vis. spectrum which is a characteristic band for the wurtzite hexagonal pure ZnO. Moreover, systematic time-dependent reactions were also performed to know the detailed growth process for the synthesised ZnO nanostructures.

Fabrication and Characterizations of Ethanol Sensor Based on CuO Nanoparticles

In this paper, we report the synthesis, characterization and ethanol sensing applications of CuO nanoparticles. The CuO nanoparticles were prepared by a facile, low-temperature hydrothermal method and characterized in detail in terms of their structural, morphological, compositional and crystalline properties, through different characterization techniques including X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), and Fourier transform infrared (FTIR) spectroscopy. The detailed studies revealed that the synthesized CuO nanoparticles were well-crystalline and possessed monoclinic crystal structure. The synthesized CuO nanoparticles were utilized for the fabrication of highly sensitive ethanol gas sensor. At an optimized temperature of 320 °C, high sensitivity (Ra/Rg) of 39.29 was observed for 200 ppm of ethanol gas. Additionally, very low response (τres = 14 s) and recovery (τrec = 30 s) times were observed for 100 ppm of ethanol.

New non-linear electrical-thermal switching of carbon nanoparticles/silane coupling agent reinforced phenolic resin nanocomposites

This paper evaluates the use of a new multifunctional conducting polymer containing phenolic resin reinforced by carbon black (CB) nanoparticles modified by silane coupling agent to produce positive temperature coefficient (PTC) thermistors and switching current. The percolation threshold of the conducting composites at room temperature was found to be as low as 4 wt% of CB. Temperature dependent electrical characterisation of phenolic resin/CB nanocomposites is performed. The composites exhibit PTC properties with ρmax/ρmin value as great as 104. Electrical parameters such as charge carriers type, drift mobility, concentration of charge carriers, activation and hopping energy are verified with CB content. The current-voltage curves of the nanocomposites change from linear to non-linear behaviour and the switching current is observed within the non-linear regime.

Preparation, characterisation and optical properties of zinc oxide nanoparticles obtained by new intercalation chemical route

A new simple intercalation chemical route was used to synthesise ZnO nanoparticles via ZnO, sodium doclecyl sulfate as a surfactant and hydrogen peroxide at 90°C with strong stirring for five hours. The results of X-ray diffraction (XRD) and Fourier transformer infrared spectroscopy (FTIR) show that ZnO nanoparticles are all of crystalline hexagonal zincite phase. The results of scanning electron microscopy (SEM) and XRD indicate that the mean sizes of ZnO nanoparticles is about 25 nm. The thermal gravimetry reveals that the as-prepared ZnO has good thermal stability. Compared with other synthesis approaches, the proposed method can get fairly good product with a relatively low cost. The optical band gap energy of ZnO was 3.17 eV.

Dielectric properties of Bi-based superconductors nanoparticles filled natural rubber/low density Polyethelene nanocomposites

A new nano conducting polymer composite containing natural rubber (NR) filled with Bi-based superconductor (BSCCO) nanoparticles was successfully fabricated using a traditional milling rubber technique. The scanning and transmission electron microscopic (SEM, TEM) studies provide information on quality of these samples and the uniform distribution of BSCCO particles within NR matrix. The electric conductivity and dielectric measurements have been carried out in the frequency range of 50 Hz-1 MHz and temperature range of 298-428 K. The measured impedance data were analysed on complex plane and the dc (bulk) as well as ac conductivity were obtained. Studies of dielectric constant as a function of frequency at different temperatures revealed that the compounds do not have any dielectric anomaly in the studied frequency and temperature range. The enhancement of the dielectric properties of nanocomposites makes it feasible as co-fired dielectric component devices.