Advanced Materials Research Vols. 194-196

Abstract: The sliding wear behavior of polyamide6/ultrahigh molecular weight polyethylene (PA6/UHMWPE, 90/10) blends loaded with 20 % carbon short fibers (CSF) as reinforcement and varying amounts of nanoclay filled nanocomposites were reported. Sliding wear loss, specific wear rate and coefficient of friction were investigated. 3 % nano clay filled composite exhibits better wear behaviour. Morphological study was evaluated for wear out surfaces of the composites using scanning electron microscopy.

Abstract: With the different sizes of the structure parameters of the SOI(Silicon on Insulator) rib waveguide, the dispersion and the nonlinearity parameters are investiaged using the beam propagation method. It is found that for the same structure parameters, the dispersion and the nonlinearity parameter γ are different between the TE and TM modes. With the changing of the structure parameters the anomalous dispersion and the nonlinearity parameter γ can be up to 972 ps/km/nm and 1.065×10⁶w^-1.km^-1 in the wavelength region near 1550nm.The high anomalous dispersion and the nonlinearity parameter γ means it’s a good candidate to realize parametric amplification and wavelength conversion.

Abstract: The spin-polarized transport is investigated in a magnetic tunnel junction which consists of two ferromagnetic electrodes separated by a magnetic barrier and a nonmagnetic metallic spacer placed in distance above the two dimensional electron gas (2DEG) in presence of an inhomogeneous external modulated magnetic field and a perpendicular wave vector dependent effective potential. Based on the transfer matrix method and the nearly-free-electron approximation the dependence of the conductance and spin polarization on the Fermi energy of the electrons are studied theoretically the. strong oscillations with large amplitude investigated in spin polarization in terms of the Fermi energy due to the inhomogeneous magnetic field. The conductance in terms of the Fermi energy shows no oscillation in low energy but has a strong pick in middle region. this results may be useful for the development of spin electronic devices based on coherent transport, or may be used as a tunable spin-filter.

Abstract: The controlled synthesis of SrCO₃ microstructures with different morphologies, such as flower-like, cauliflower-like and finger-like, were successfully achieved in the presence of mixed nonionic/anionic surfactants polyoxyethylene (20) sorbitan monolaurate (Tween20) and sodium dodecyl sulfate (SDS). Results indicated that SDS/Tween20 complex micelles played important roles in the morphological control of SrCO₃ microstructures. Also, the influence of CO₃^2- concentration on the morphology of SrCO₃ crystals was investigated and discussed. X-ray powder diffraction (XRD), fourier transform infrared spectroscopy (FT-IR) and field-emission scanning electron microscope (FE-SEM) were used to characterize the as-synthesized crystals.

Abstract: Ultrasonic oscillation and nanometer grind were used to treat ZnO suspension, and the effects of treatment time on preparation of ZnO were investigated. PEG400 was chosen as a suitable surfactant to reduce aggregation problem because PEG400 is not only effective at keeping the stability of ZnO suspension, but also has no influences on diameter size of ZnO nanoparticles or antibacterial ability. The effects of concentration and particle size on antibacterial ability of ZnO suspension were evaluated. The results demonstrated that the optimum time of ultrasonic oscillation for reducing aggregation is 0.5 h, and diameter size exhibited linear decline during the first 1 h of nanometer grind. Antibacterial ability increased with the increasing of the concentration of ZnO nano-suspension until it reached 0.25 g/L, and antibacterial ability was inversely proportional to diameter size of ZnO nanoparticles.

Abstract: ZnSn(OH)₆ hierarchical cubes and Zn₂SnO₄ octahedra have been synthesized through a rapid, template-free, one-pot hydrothermal approach using zinc acetate, tin chloride and sodium hydroxide. ZnSn(OH)₆ aggregates with cubic morphology and uniform size distribution have been successfully synthesized via aggregation-mediated crystallization. Through adjusting the hydrothermal parameters, Zn₂SnO₄ octahedra were obtained at a higher temperature. The formation of Zn2SnO4 octahedra undergone a transformation from ZnSn(OH)₆ cubes. The as-synthesized products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calorimetric analysis (DSC) and thermogravimetric analysis (TG).

Abstract: In order to analyze the influences of process condition on kerosene-based Fe₃O₄, which are prepared in chemical co-precipitation, orthogonal experiment was used. How process condition influenced the size of nano-particles and saturation magnetization was studied, and the best process condition as 40ml•min^-1 NaOH adding speed, 10ml•min^-1 sodium oleate adding speed, 45°C reaction temperature, 15min holding time and pH value of 2 of coating sodium oleate was obtained. The performance of magnetic particles was characterized by transmission electron microscopy (TEM) and WSM vibration magnetometer. The diameter of Fe₃O₄ nano-particles was less than 10nm, saturation magnetization was 2.66×10⁴A•m^-1, viscosity of nano-magnetic fluid was 18mPa•s, and density was 1.13×10³kg•m^-3. This research enhanced the foundation of using nano-magnetic fluid.

Abstract: A novel approach to synthesis cubic pyrochlore lead zinc niobate-based Pb_1.88Zn_0.3Nb_1.25O_5.305 nanopowders with a modified mixed-oxide method has been developed. To ensure a pure phase pyrochlore formation, an intermediate phase of Zn₃Nb₂O₈ was employed as key precursor. The formation of pyrochlore phase in the calcined lead zinc niobate powders has been examined as a function of firing temperature by a combination of TG-DTA and XRD techniques. The morphology evolution has been examined by SEM technique. It has been found that the unreacted PbO and Zn₃Nb₂O₈ phases tend to form together with lead zinc niobate, with the latter appearing in cubic phase. It is seen that optimization of firing temperature can lead to a single-phase Pb_1.88Zn_0.3Nb_1.25O_5.305 powders with average particle sizes ranging from 75-400 nm.

Abstract: A novel piperazine derivative (4, 4'-(1, 4-piperazinediyl) bis (4-oxo-2-butenoic acid),PBBA) was successfully synthesized under mild conditions by using piperazine and maleic anhydride as feedstock. Its molecular weight and structure were characterized through High-performance liquid chromatography-electrospray mass spectrometry (HPLC-EMS) and Nuclear magnetic resonance (NMR). Then its especial micrystal was also obtained by recrystallizing through co-precipitation in dimethyl sulfoxide-ethanol system. Scanning electron microscopy (SEM) and optical microscope revealed that the uniform shape microcrystal, which length ranging from 5 μm to 50 μm and width ranging from 2 μm to 15 μm, have unusual optical properties that lights only can be refracted through the middle of the microcrystal, maybe due to its special molecule structure.

Abstract: Experiments were conducted on copper subjected to High Pressure Torsion to investigate the evolution of microstructure and microhardness with shear strain, γ. Observations have been carried out in the longitudinal section for a proper demonstration of the structure morphology. An elongated dislocation cell/subgrain structure was observed at relatively low strain level. With increasing strain, the elongated subgrains transformed into elongated grains and finally into equiaxed grains with high angle grain boundaries. Measurements showed the hardness increases with increasing γ then tends to saturations when γ >5. The variation tendency of microhardness with γ can be simulated by Voce-type equation.