Advanced Materials Research Vol. 669

Abstract: The conductive adhesives were prepared by using micron silver, ball-milled silver and the mixture of them as conductive fillers, respectively, and epoxy resin as matrix. In this study, The relationship between the resistivity with the content of silver fillers was tested. With the micron sliver loading from 60 wt% to 75 wt%, the resistivity decreases significantly about 8 orders of magnitude. And the effects of the different types of silver fillers (micron silver, ball-milled silver and the mixture of them) on the resistivity were also investigated. The study shows that the ECAs filled with the micron sliver gets the highest resistivity and the resistivity of ECAs which uses the ball-milled sliver as fillers is the lowest.

Abstract: The nanoscale magnetic composite powders BaFe12O19-ZnFe2O4 were prepared by two-step citrate sol-gel, with analytically pure Fe(NO3)3、Zn(NO3)2 and Ba(NO3)2 as the main materials. The XRD, TEM and VSM were used to analyze the structure, feature and magnetic property of the nano-powder. The results show that the same presoma is calcined in 600°C、650°Cand 700°C obtained BaFe12O19-ZnFe2O4，XRD display for both pure phase, do not contain any mixed phase。The higher the temperature, the content of magnetoplumbite phase increased, corresponding the content of spinel phase low。By hysteresis loop of composite powde BaFe12O19- ZnFe2O4 can see, simple substance BaFe12O19 magnetoplumbite phase has the wasp waist shaped hysteresis loop，simple substance ZnFe2O4 spinel phase has superparamagnetism，but the nanoscale composite powders BaFe12O19-ZnFe2O4 has rectangular hysteresis loop。

Abstract: Zinc oxide (ZnO) films were prepared on Si substrates and then aluminum nitride (AlN) films were deposited on ZnO films by radio frequency (RF) magnetron sputtering. The crystal orientation, crystallite structure and surface morphology of AlN/ZnO films were characterized by X-ray diffraction (XRD), Raman spectrum and scanning electron microscopy (SEM). It was indicated that the AlN films were closely deposited on the ZnO film and had good crystallinity. Moreover, about 1μm-sized crystal particles with high c-axial orientation distributed uniformly on the AlN/ZnO film surface. It was indicated that ZnO could be a promising candidate as buffer layer for preparation of AlN thin films.

Abstract: Polyacrylonitrile (PAN) hollow fiber ultrafiltration membranes were prepared by wet spinning method using lithium chloride (LiCl) or calcium chloride (CaCl2) as porogen and dimethyl formamide (DMF) as solvent. The effects of PAN/LiCl and PAN/CaCl2 ratios in the spinning solution on the permeation properties of the formed membranes were studied.

Abstract: Single-crystalline ZnO nanotubes were fabricated via a simple aqueous solution method under low temperature and atmospheric pressure conditions. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) equipped with the selected area electron diffraction (SAED) setup were used to analyze the crystal structure, surface morphology and inner structure of ZnO nanotubes. Photoluminescence (PL) and UV-visible absorption spectra were carried out to investigate optical properties of ZnO nanotubes. The results indicate ZnO nanotubes only exhibit sharp and strong near ultraviolet emission at 363 nm according to PL spectrum.

Abstract: We simulate and calculate numerically the electromagnetic field and energy flux in single crystal silicon thin film solar cell coated with silver nano-disk square array by using the finite-difference time-domain (FDTD) method. Because of the surface plasmon resonance (SPR) of silver nano array, the electromagnetic field is redistributed and enhanced in the solar cell. The simulation results show that the electromagnetic field distribution and corresponding energy flux component depend on the nano array and the structure of absorbed layer in solar cell. The wavelength of the incident light relative to the nano array determine the profile of the electric field around the nano array. The electromagnetic field distribution in thin film is determined by the internal structure of solar cell. For different incident wavelengths, the electromagnetic field distribution in solar cell will changes. The energy flux named as Poynting vector also changes with the incident wavelength. To investigate the absorption of the solar cell, the normalized absorbed power at different wavelengths is calculated. Based on the SPR effect, the solar cell exhibts absorption enhancement sharply at a certain wavelength.

Abstract: Series of ferroelectric glass-ceramic samples of Sr0.5Ba0.5Nb2O6 were synthesized by melting method. Firstly, analytical reagents were melted for 30 minutes at 1440°C after being grinded evenly according to a certain molar ratio, then annealed for 10 hours from 550°C to room temperature, finally it was sustained for 4 hours at constant temperature about 700°C. The hardness and transmittance parameters of SBN glass-ceramic were tested. Results indicated the sample had the best property when the amount of Nb2O5 was 10mol%, whose hardness reached 506 kg/mm2, and spectral transmittance was higher than 35% . XRD spectra of this sample indicated this SBN glass-ceramics contained a large number of Sr0.5Ba0.5Nb2O6 crystalline phase and a small amount of Sr0.3Ba0.7Nb2O6 phase. The particle size was about 50 nm.

Abstract: This paper intends to deal with one novel profile control agent formed by combination of HPAM and cationic microspheres with different cationic density (CD) by the method of micro-emulsion polymerization. Profile control is of great importance in well stimulation for current oilfield with high water cut. The main profile control agents now are polymer or polymer microspheres. Each of these agents has its own performance advantages. The novel profile control agent is equipped with the advantages of both the agents mentioned above. Analyzed by transmission scan electron microscope (TSEM) and laser particle sizer, the particle size of the original synthesized microsphere and the swelled microsphere in water are 50-100nm and 1-3μm respectively. Analyzed by micro-electrophoresis, the surface potential arrives at its highest value at 30% of the cationic density; aggregation happens when CD is low and the electrostatic force is insufficient to keep the system stable. Due to electrostatic interaction, the synthesized system flocculates at a concentration of 0.02% separately. Measured at varied shear rates, the viscosity of the system can be significantly enhanced by electrostatic interaction. However, this enhancement is not obvious when the salinity is higher than 3%, which indicates that the increasing of viscosity is closely related to the salinity of solution. Moreover, by increasing hydrolysis degree of HPAM, the viscosity of the system can be improved by 20% additionally. Through core displacement test, the synthesized system is proved to have relatively good profile control performance.

Abstract: The effect of HF concentration on the surface structure of porous silicon (PS) was carefully investigated by the AFM characterization. The results showed that no pores were present on PS surface which was prepared under the higher concentration of HF (10%). However, the pores were gradually visible with the HF concentration reduction. The main pores diameter was about 100 nm, when the concentration is 5.71%. The data of surface roughness and the main height distribution of the “hill” both showed an increase with the reduction of concentration, from 6.39 nm increase to 16.9 nm and from 30 nm increase to 90 nm, respectively, which implied that the pores were better exposed under the lower HF concentration.

Abstract: Abstract. This paper describes that high-yield Ag/C coaxial nanocables has been obtained via a simple hydrothermal approach through the in situ reaction of Ag+ and glucose in the condition of CTAB. The glucose not only acts as reducing agent but also as carbon source. It was found that high aspect ratio(>400)of nanocables with Ag nanowires core diameter (20-60)nm and various carbon shell thickness had been prepared in large scale with a facile aqueous reduction route at low temperatures for different times. All of the products were characterized in detail by multiform techniques: X-ray diffraction(XRD), transmission electron microscopy(TEM), high-resolution TEM(HRTEM), scanning electron microscopy(SEM), energy-dispersive X-ray spectroscopy (EDX).