Advanced Materials Research Vol. 1035

Abstract: Coaxial nanocomposites were prepared by in–situ chemical polymerization of 4– dibromomethyl–2,5–2–octyloxy phenylene in the presence of multiwall carbon nanotubes. The morphology, microstructure and thermal and electrochemical properties of the resulting nanocomposites were investigated by scanning electron microscopy, Fournier infrared spectroscopy, thermal gravimetric analysis and cyclic voltammetry. The results indicated that the nanocomposites with uniform core-shell structure exhibited higher thermal stability than neat poly (phenylene vinylene). Furthermore, energy storage ability of these coaxial nanocomposites as electrode materials for supercapacitor was evaluated.

Abstract: The ultralong copper nanowires (Cu NWs) with diameter of 90±10 nm and length over 20 μm were synthesized by the self-assembly growth process, in which the copper ions were reduced with hydrazine in an aqueous solution containing NaOH and ethylenediamine (EDA). The prepared Cu NWs were characterized by XRD, SEM and TEM. The results indicate that the ultralong Cu NWs product almost containing no particles can be obtained at 80 °C for 1 h with a proper concentration of EDA. During the growth of Cu NWs, as the EDA moleculars are possibly preferentially absorbed onto the crystal plane of (110), the gowth of Cu NW will be oriented along the crystal plane of (111).

Abstract: Copper Oxide (CuO) microfibers with different morphologies were prepared by the electrospinning and calcination process. The formation process of CuO microfibers was analyzed by thermogravimetry and their microstructures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed the spinnability and electrical conductivity of the polymer solution are affected by the concentration of acetic acid solution. The morphologies of CuO are closely related to the calcination temperature. The thin-walled tubulous microfibers can be obtained by calcination of the electrospun precursor with 8 wt.% acetic acid at 500 ^○C for 2 h.

Abstract: In this paper, the prepared nanocomposite BaFe₁₂O₁₉/α-Fe microfibers and nanocrystalline magnetic alloy Fe_0.2(Co_0.2Ni_0.8)_0.8 microfibers are used as absorbents in the double layer structure for microwave absorption. The double layer absorbers with a total thickness of 2.0 mm, in which various matching and absorbing layers are designed, and their absorption properties are estimated. The results show that the absorbers with the matching layer of nanocomposite BaFe₁₂O₁₉/α-Fe microfibers have a very high microwave absorption performance. The absorption bandwidth (the reflection loss (RL) less than-20 dB) reaches 5.8 GHz ranging from 12.2 to 18 GHz, and the minimum RL value is-61.2 dB at about 15.2 GHz with 0.9 mm matching layer and 1.1mm absorbing layer respectively.

Abstract: As for the low yield and high consumption of electrolyte in conventional anodization for TiO₂ nanotubes, several schemes were proposed to optimize the unit yield. The anode surface area per unit volume of electrolyte and the homogeneity of the electric field are found to affect the unit yield of well-structured TiO₂ nanotube besides voltage, F^- and water content, reaction time and temperature, etc. Experimental results show that the unit yield over the cylindric electrodes quadruples in comparison with conventional anodization, which is attributed to higher anode surface area and homogeneous electric field. And SEM image indicates that well-structured TiO₂ nanotube arrays are fabricated. Thus it can be concluded that the unit yield could be increased by the method proposed in this paper and that our work provides a reference for the bulk preparation of TiO₂ nanotube and the energy-saving and emission-reduction in the process.

Abstract: The self-organized oxide nanotube/pore layers were prepared by anodization on ternary Ti-6Al-4V alloys. The morphologies and structures of layers under different heat treatment tempreture were characterized by means of SEM, XRD, XPS and Raman spectroscopy and DRS. The effects of alloying element under different heat treatment tempreture on the structure, composition and opsorption property of the film catalysts were investigated along with their inherent relationships. The results show that two kinds of Ti-Al-V-O nanostructure grown inthe α and β phase region formed on the surface of the alloy. V doped-TiO₂ can inhibit the formation of anatase. The films show the microcrystalline structure of anatase and rutile and a small amount of V₂O₅ on the surface of film annealed at 400 oC. Moreover, the large surface and the synergy effect of V-doped TiO₂ and V₂O₅ make sample show the highest photocatalytic activity for the photocatalytic hydrogen evolution.

Abstract: Magnetic nanocrystalline alloy Fe_0.2(Co_0.2Ni_0.8)_0.8 microfibers and nanocomposite SrFe₁₂O₁₉/Ni_0.5Zn_0.5Fe₂O₄ microfibers are used as the absorbents in the double-layer structure for microwave absorption. The double-layer absorbers with a total thickness of 2 mm consisting of Fe_0.2(Co_0.2Ni_0.8)_0.8 and nanocomposite SrFe₁₂O₁₉/Ni_0.5Zn_0.5Fe₂O₄ microfibers are designed, and their microwave absorption properties are predicted based on the electromagnetic parameter measurements. The results show that the double-layer absorber with the absorption layer of SrFe₁₂O₁₉/Ni_0.5Zn_0.5Fe₂O₄ microfibers and the thickness of 0.6 mm has the best microwave absorption properties, with the bandwidth ( the reflection loss less than −10 dB) of 7.3 GHz ranging from 10.7 GHz to 18 GHz, and the maximum reflection loss of −71.4 dB at 12.1 GHz.

Abstract: In this paper, a Li-rich cathode material Li_1.2Mn_0.6Ni_0.2O₂ is modified by the nanoscale TiO₂ coating using a simple and controllable hydrolyzation method. The effect of nanoscale TiO₂ coating on the bulk structure, surface morphology and electrochemical performance are characterized by X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and electrochemical techniques, respectively. The results show that the nanosize TiO₂ can be well coated on the surface of the cathode material. The coating layers have no influence on the bulk structure of the cathode material, while they can improve the initial discharge capacity, columbic efficiency and cycling performance.

Abstract: Pure and single-phase ceria particles were synthesized by an anodic electrochemical method followed by annealing at 500-900°C for 2h. Many characterization methods have been used to study the ceria nanostructures and electronic structures, including X-ray diffraction, transition electron microscopy and UV-vis spectrophotometer. The average crystallite size was estimated to be the scale of nanometers. While annealing at a low temperature, ceria particles are a little agglomeration and are termed as mesocrystal. It is observed to increase the crystallite size in addition to increase the crystalliminty of the nanoparticles while increasing the annealing temperature. The absorption spectra show that the ceria nanoparticles have direct and indirect band gap structures. There is a red shift of the absorption peak for the particles after annealing. Both the direct and indirect band gap energies are found to decrease with the annealing temperature.

Abstract: Ar\H₂\CH₄ gas mixture was utilized to grow nanocrystal diamond films in a RF plasma enhanced CVD system. CH₄\ H₂ ratios were changed to study the effect of plasma radicals on the deposit, in which optical emission spectroscopy (OES) was applied to analyze the plasma radicals. It was found that H_α, H_β, H_γ, CH, C₂ were the main radicals in the plasma. Among them, the CH intensity of OES was usually quite strong and increased sharply when the ratio of CH₄/H₂ was greater than 3%. The intensity of C₂ was weak and basically unchanged with the addition of methane. This study can provide a new possible technical application for depositing NCD films.