Advanced Materials Research Vol. 924

Abstract: AP-based nanolimit growth energetic materials (NLGEM) were prepared by using SiO₂ gel as nanolimit growth skeleton materials and using sol-gel method combining solution crystallization to make AP recrystallized in the nanopores of SiO₂ gel skeleton to form AP/SiO₂ NLGEM. The chemical and physical structure and properties of AP/SiO₂ NLGEM were studied in detail. AP with nanoscale particles size range from 69nm to108nm was recrystallized in the pore of SiO₂ gel skeleton and the particle size of AP increased with the amount of AP in NLGEM increasing. Moreover, the preparation method didnt change the crystal form of AP and bring impurities to NLGEM. The decomposition of AP/SiO₂ NLGEM was a one-step process, which was indicated its decomposition was more concentrate than pure AP and AP/SiO₂ simple physical mixture (AP/SiO₂ SPM), whose decomposition was a two-step process. At the time, the decomposition heat of AP/SiO₂ NLGEM was higher than that of pure AP and AP/SiO₂ SPM. The sensitivity of AP/SiO₂ NLGEM was lower than those of the pure energetic components and physical mixtures according to the impact sensitivity test.

Abstract: Polyimide/nano-SiO₂ (PI/SiO₂) composites with different contents of SiO₂ were prepared by in situ polymerization. The transmittance, solubility, thermal property, flame retardant properties and mechanics properties of PI/nano-SiO₂ composites were investigated. The results showed that with the increased addition of SiO₂ content, the transmittance of PI/SiO₂ compositions reduced; tensile strength changed with the amount of nanometer powder, when the addition content was 10 wt%, it achieve the maximum value. Thermal resistance of the composite was improved obviously while with the amount of nanometer powder increased, volume resistivity coefficient of volume resistance would have decreased.

Abstract: The (Mg_0.8Zn_0.2)TiO₃(MZT) as the foundation is mainly studied to join high dielectric material Ba₄Nd_28/3Ti₁₈O₅₄·zBi₂O₃(BNT) to preparation microwave dielectric ceramic 0.7(Mg_0.8Zn_0.2)TiO₃·0.3{Ba₄Nd_28/3Ti₁₈O₅₄·zBi₂O₃}(z=0.15, 0.18, 0.2) to improve dielectric properties of MZT. While Bi³⁺ could reduce the sintering temperature to make MZT and BNT composite in a lower sintering temperature (1200~1230 °C). According to the results of the dielectric properties, density, XRD and SEM tests of the obtained ceramics, we can find out that the amount of doped Bi³⁺ and the sintering temperature affected the structure and properties of the ceramics. The results show that when z=0.18, 0.7(Mg_0.8Zn_0.2)TiO₃·0.3{Ba₄Nd_28/3Ti₁₈O₅₄·zBi₂O₃}

Abstract: The nitrogen doped nanoTiO₂ was prepared by the microwave-assisted method. The properties were characterized by the X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The effects of the calcination temperature and the doping amount of nitrogen on the nitrogen doped nanoTiO₂ crystal phase and its photocatalytic properties were studied. The result indicated that with the increase of the calcination temperature, the proportion of rutile in the mixed crystal phases increased gradually. When the calcination temperature was 650°C, the pure rutile phase appeared. When the TiO₂ was calcinated at 400 °C, the particle size was the minimum (17nm). This mixed crystal was conducive to the good photocatalytic properties of nanoTiO₂. The degradation rate of methyl orange was 50.86%. At the calcination temperature of 450 °C, the proportion of rutile in the mixed crystal phase increased first and then decreased, until finally it increased again with the increase of the doping amount of nitrogen. When the ratio of nitrogen to titanium was 1:0.5, the catalytic effect was the best. The photocatalytic degradation efficiency was 71.63%, and the particle size was also approximately the minimum (15nm).

Abstract: Employing yeast cells as carriers,a novel cell-loaded photocatalyst yeast/ZnS (YC/ZnS) was successfully synthesized. The adsorption performance of methylene blue on the YC/ZnS microspheres was studied. Experimental results showed that the optimized adsorption conditions were 23°C,pH7 and the YC/ZnS dosage 4.5g/L. Under these conditions,the adsorption capacity of YC/ZnS could reach 471.2μg/g. Isotherm modeling revealed that Freundlich equations described well the adsorption of methylene blue onto YC/ZnS.

Abstract: Hydrophobic surfaces with contact angles greater than 90° and roll-off angles below 10° for water have been developed, based on low energy surfaces and rough texture on the micro-and nanometer scales. In this study, we fabricated a hydrophobic surface on a aluminum alloy substrate using the method of chemical etching without being modified by organic liquids such as surfactant-based solutions, alcohols, or alkanes. The measurement showed that the as-prepared surfaces possessed roughness on the micrometer scales by laser scanning confocal microscopy. The etched aluminum alloy surfaces had a maximum water contact angle of 120^o by using a water contact angle measurement. The forming course of the aluminum alloy etched surfaces with pores was analyzed. The wettability of the etched aluminum alloy surfaces is reinforced by means of controlling the surface rough texture on the micrometer scales.

Abstract: The magnetic FeCoGd thin films with various sputtering power from 10 to 30 W were fabricated on glass substrates by magnetron co-sputtering. The crystal structure of as-deposited FeCoGd thin films was investigated by X-ray diffraction. And an increasing trend of grain size with the increasing sputtering power was shown. When sputtering power is below 30 W, the films exhibited obviously in-plane uniaxial magnetic anisotropy, and the in-plane magnetic anisotropy field H_k decreased with increasing deposition power. Moreover, good high frequency characteristics were obtained. The magnetization reversal mechanism has been investigated via the in-plane angular dependences of the magnetization and the coercivity. The experimental data points indicated that the magnetization reversal mechanism of FeCoGd film with in-plane uniaxial anisotropy is domain-wall depinning and coherent rotation when the applied field is close to the easy axis and hard axis, respectively. A spin reorientation transition phenomenon was observed when deposition power is larger than 30 W. A stripe domain structure for the sample with 30 W deposition power was developed due to a dominated perpendicular magnetic anisotropy.

Abstract: Dressing field control of band gap reflection is investigated in an inverse Y-type four-level atomic system. It is shown that when the dressing field is blocked, a band gap reflection with a maximum bandwidth and nearly ~90% reflectivity can be achieved for the detuning of the coupling field . When a weak dressing field is applied to the system (the intensity is much less than that of the coupling field), a narrowing top flat with ~86% reflectivity of the band gap reflection is observed in comparison with that in the first case. We also show that the band gap reflection can be dramatically suppressed due to the collapse of the stop band when a strong dressing field (the intensity is comparable with or larger than that of the coupling field) is employed. This control of photonic band gap reflection can be used in the applications of all-optical reflection mirrors and band optical filters.

Abstract: We studied the optical properties of silica colloids suspensions made of nanospheres having an average diameter of 50, 90, 120, and 300 nm in electric field. It was illustrated that a colloidal suspension with a particle size of 120 nm shows a dramatic change of the reflection peak position in response to the applied potential. With the increase of the concentration, the position of peak maximum slightly blue-shifted and the reflection intensity slightly increased. The impact of solvents on optical properties of silica colloids suspensions was studied. It was demonstrated that the position of peak maximum has a dramatic change only in propylene carbonate; there were no marked changes in ethylene glycol and water. The intensity of reflection peak was strongest in water. We analyze the mechanism and attribute this phenomenon to the hydrogen-bonding ability of the solvents.

Abstract: Ni-P ultra-black films having conical pores with the diameter of ~ 10-30 μm and the depth of ~ 15-30 μm were prepared by chemical etching of electroless plated Ni-P films using 8 mol/L nitric acid at 40 °C for 60 s. The phase composition and microstructure of the film samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the diameter and depth of the etching pores become larger and the flat top regions bounded by etching pores become smaller by the coalescence of adjacent pores with the increase of etching time. The surface morphologies of the etched Ni-P films are characterized by the distribution of conical pores.