Advanced Materials Research Vols. 306-307

Abstract: The process of dense phase pneumatic conveying gypsum in stepped pipeline was simulated by using an Euler-Euler two fluid model of dense gas-particle two phase flow based on the kinetic theory of gas and granular. The simulation results showed dynamic pressure increased while static pressure decreased in the first two tapered pipe, but this trend became opposite in the last diffuser pipe. The gas and particle velocity both increased in the 80-65mm and 65-50mm tapered pipe, but decreased in 50-80mm diffuser pipe. In a short, the results showed that the simulation was consistent with the fact, which proved the feasibility of our simulation.

Abstract: Hydrophobic mesoporous silica aerogels were synthesized using cheap industrial grade tetraethyl orthosilicate (TEOS) as precursor by ambient pressure drying.The silica alcogels were prepared by acid-base sol-gel polymerization of the TEOS, the surfaces of silica alcogels were modified using trimethylchlorosilane/ hexamethyldisiloxane via simultaneous solvent exchange and surface modification. The attachment of trymethylsilyl (-Si(CH₃)₃) groups to the silica surface was confirmed by the presence of Si-CH₃ peaks at 2963, 1256 and 845 cm−1 in the IR spectra. Properties of the aerogels were examined by SEM, TEM, XRD, BET and DTA-TG analyses. The results indicate that the aerogels in a typical amorphous state have a highly porous network with an average pore diameter in the range of 5–10 nm, have high specific surface area (931 m²/g) and are thermally stable up to 322 °C.

Abstract: The porous ZrO₂ ceramics was prepared by spark plasma sintering (SPS) at 520 °C. A dense closed micro-cellular ceramic structure was fabricated with micron Al₉₀Mn₉Ce₁ alloy powders clading by 10 wt% ZrO₂ nano-powder. SEM image showed that the thickness of ceramic cell wall was 1.0 - 2.0 μm. After deep corrosion with 10% HCl, an integrity nanocrystalline ZrO₂ porous sample was obtained. Based on the experimental results, the transient spark plasma sintering mechanism of micron-nano mixing powder was also studied.

Abstract: Al-doped ZnO (AZO) thin films (~100nm) with low electrical resistivity and high transparency have been prepared by atomic layer deposition on glass and Si(111) substrates at 200 °C with different doping sequence. The films were systematically analyzed using X-ray diffraction, scanning electron microscope (SEM), UV-vis spectroscopy and Hall measurement. XRD patterns showed that all the films were well crystallized with hexagonal wurtzite structure with preferred orientation along (100) plane. The resisitivity of films deposited with doping sequence of DEZ/TMA/H₂O was lower than that with other doping sequences. Results from SEM showed a worm-like shape and similar grain sizes of AZO films. Optical transparency of AZO films was measured to be >90% for wavelengths of 400-1000 nm.

Abstract: Au/brush-Zn heterojunction nanowires were synthesized by using the Anodic Alumina Membrane (AAM) template combine with DC electrodeposition. As-prepared Au/brush-Zn nanowires were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive x-ray spectrometer (EDS). Secondary growth mechanism is proposed for the formation of Zn brush structure. The Au/brush-Zn nanowires exhibit a strong absorption in a broad range of wavelength especially between 200 and 360nm, which may be ascribed to the transition of the electrons from the d band to the s, p conduction band near the Fermi surface and the transition from valence bands to conduction bands for Zn brush associated with enhancement of Au.

Abstract: Cu-Al₂O₃ (Co-Al₂O₃) nano-array composite structures assemblies with Cu (Co) grown in the pores of an anodic alumina membrane (AAM) were obtained by alternating current electrode position. Their transmitted spectra and polarized spectra are systematically investigated. Experimental results indicate that the transmittance of Cu-Al₂O₃ is superior to that of Co-Al₂O₃ in visible and infrared waveband, but the extinction ratio of Co-Al₂O₃ is better than that of Cu-Al₂O₃ in near infrared waveband.

Abstract: The Bi₂Ti₄O₁₁ nanorods were obtained by a one-step alcohol-thermal method. The sample was synthesized at 100°C and calcined at 600°C, using Bi(NO₃)₃•5H₂O, TiCl₄ and absolute ethanol as reactants. It then characterized by XRD, SEM and UV-vis DRS. The results showed that the sample was nanorod with diameter about 30nm and length about 200nm. The photocatalytic experiment represented that the photocatalyst could effectively degrade more than 99% Rhodamine B( RhB) within 85 min under irradiating of visible light.

Abstract: MCM-48 microspheres have been repeatedly synthesized in cetyltrimethylammonium bromide-tetraethylorthosilicate-ammonia solution-water media with a fixed alcohol-to-water molar ratio of 0.15 by increasing the amounts of water and ethanol simultaneously. The cubic ordered pore arrangement is proved by the XRD and TEM measurements. Experiments show that the sole increase in either the ethanol or water addition would result in the formation of MCM-41 mesophase. The results indicate that the alcohol-to-water molar ratio is an important factor for controlling the formation of MCM-48 microspheres. The mechanism is primarily discussed.

Abstract: Removed due to double publication.

Abstract: β-Ni(OH)₂ flower-like spheres and nanoflakes were synthesized with strong ammonia water as precipitator and nickel nitrate as nickel source by the hydrothermal method. The phase structure and morphologies were analyzed using XRD and SEM. The results showed that under the same conditions of the pH value and the reaction time, the low temperature was propitious to synthesize β-Ni(OH)₂ flower-like spheres. High temperature was in favor of the synthesis of β-Ni(OH)₂ nanoflakes. Namely, β-Ni(OH)₂ flower-like spheres were obtained at 180 °C for 48.0 h with pH=9.0. β-Ni(OH)₂ nanoflakes were prepared at 240 °C for 48.0 h with pH=9.0. The formation mechanism was explored through observing influence of the conditions of the hydrothermal method on the morphologies of the samples.