Advanced Materials Research Vol. 412

Abstract: Based on the traditional method of adsorption of the hydrogen fluoride, we mainly selected some typical inorganic compounds α-Al₂O₃, γ-Al₂O₃, CaF₂ and NaF as the adsorbents, studied and discussed the effect of their adsorption ability of the hydrogen fluoride gas. Comprehensive comparison showed that NaF was the best adsorbent for hydrogen fluoride gas. Meanwhile, as the raw materials for the production of hydrogen fluoride gas, CaF₂ was also used as an adsorbent, and the measurement showed that CaF₂ has barely adsorption ability for hydrogen fluoride gas. Using the electronic analytical balance and fourier transform infrared spectroscopy, the absorption efficacy of different inorganic compounds with equal quality for the same amount of hydrogen fluoride gas was analyzed and characterized.

Abstract: The present article reports the results of studies related to the synthesis of nanocrystalline ceria powder by combustion process using salt combustion aid. Cerium nitrate as oxidant and urea as fuel were used as reagents, Sodium Chloride was compared as combustion aid. The phase analysis and particle size were compared. The product was characterized by X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy. The results showed that employment of starting fuel with combustion aid resulted in synthesizing nanocrystalline ceria powder with fine agglomerates. By using combustion aid, the energetics of the combustion reaction and particle characteristics have been changed.

Abstract: ZnO nanopowder have been prepared by chemistry liquid-phase method with the water soluble polymer and the surfactant as additive in [Zn (OH)₄]^2- precursor solution. The Character of spectroscopy and microstructure and phase composition was studied by X-ray diffraction, transmission electron microscopy and UV–Vis absorption spectroscopy. The possible influence like reaction time, reaction temperature, reactant ratios and so on was investigated. At the same time, the inorganic granule coring and the crystal growth affected by the water-soluble polymer and the surfactant were discussed. Studies have shown the ZnO nanopowder with the diameter of 50nm has the structure such as the good crystal state and well-defined crystallographic surfaces. The ZnO nanopowder have strong absorption in the UV region with the wavelength of 200 ~ 300 nm.

Abstract: The shell-core structures of SiO₂/ZnO nanopowders were obtained by simple two-step technique based on low-temperature crystallization from liquid phase. The influence of molar ratio of SiO₂/ZnO in the reaction mixture on the morphology of obtained SiO₂/ZnO nanopowders was studied. Crystalline structure of SiO₂/ZnO nanocrystals obtained was proofed by the X-ray diffraction data. The average diameter of SiO₂/ZnO nanocrystals was about 80~100nm according to FSEM and TEM data. It is shown that SiO₂ components on the surface prevent the thermal interfusion of ZnO particles. Morphology and diameter of raw ZnO, SiO₂/ZnO nanopowders prepared with molar ratio of SiO₂/ZnO 0.1, 0.2, and 0.5 were almost same. When molar ratio of SiO₂/ZnO was 0.5, ZnO core was coated with SiO₂, and the thickness of shell was about 10nm. At the same time, SiO₂ nanocrystals also formed the islands structure.

Abstract: Three-dimensitional flower-like ZnO powders were prepared by using a simple aqueous solution method. Their surface wettability was modified via some long chain alkylsilanes with low surface energy. The microstructures and the wettability properties were studied by scanning electron microscopy (SEM), X-ray diffractometer (XRD) and contact angle measurement (CAM). The ZnO powders are spheric and are about 5 micrometers in diameter. The boundary of the microspheres are not smooth, but petaliform in nanoscale, which demonstrate a hierarchical microstructure. The as-synthesized powders have a superhydrophobicity with water contact angle of more than 150°, and have a high adhesion to water. After modified by alkylsilanes, however, the ZnO powders demonstrate a strong anti-adhesion to water. When modified by fluorinated alkylsilanes, the surface of ZnO microspheres had a water contact angle up to 170°. Also, the water droplet could bounce against the surface just like a spring ball, and there are not any water traces left when the water droplets contact the surfaces of ZnO powders. The results provide a simple method to repel the water wetting and will be helpful to disperse the powders especially in a humid environment.

Abstract: In the paper, ZnO nanopowders were synthesized by using zinc acetate and sodium hydroxide as raw materials. The influences of different soft templates and synthesis temperature on the properties of ZnO nanopowders were investigated. The results showed that: when using the polyethylene glycol (PEG (400)) or polyvinyl alcohol (PVA) as soft template, the ZnO nanoparticles with the diameter about 100nm were obtained, whereas the ZnO nanorods which the length and diameter were 300nm and 150nm respectively were obtained without soft template. When the synthesis temperature was 220°C and 70°C, the ZnO nanorods were obtained. When the temperature was 100°C, the ZnO nanosheets were produced, and the length, width and thickness of ZnO nanosheets were about 800 nm, 500nm and 80nm, respectively. When the temperature was 90°C, the ZnO nanosheets composed with nanorods were prepared.

Abstract: The nanosized TiO₂ is prepared by micro-emulsion process in the system of cyclohexane / [Span80 combined with OP-10] / water with TiCl₄ as raw material. The selection method of the surface-active agents was investigated and the influence of amount of surfactant, water / oil ratio and concentration of reactants on the particle size were discussed in this work. The temperature schedule, crystal structure, particle size distribution and appearance of the nanocrystalline TiO₂ were analyzed by differential thermal analysis (DTA) combined with X-ray diffraction (XRD), laser particle size analysis (LPSA) and scanning electron microscope (SEM). The results showed that: under these conditions of mixture of 8g Span80 and 2g OP-10 as the emulsifier, water / oil mass ratio of 1/4, TiCl₄ concentration of 0.6mol / L and calcinations temperature of 510°C, nanoTiO₂ powder with smaller particle size and better dispersion was prepared . And the average size of the product was 27.3nm.

Abstract: TiO₂ nanopowders were synthesized by non-hydrolytic sol−gel method. Effects of TiCl₄ concentration and acidity on the properties of TiO₂ nanopowders were investigated. The results showed that the average grain size of TiO₂ decreased with the increasing of TiCl₄ concentration. H⁺ can inhibit the growth of TiO₂ particles and Cl^- is conducive to the formation of rutile phase. When 2.06M HCl was used as the reaction solution, TiO₂ microspheres with diameter 2μm was obtained, and TiO₂ microspheres was composed of anatase and rutile phase.

Abstract: TiO₂ nanopowders were synthesized by solvothermal synthesis method. Effects of different solvents and dodecylbenzenesulfonic acid sodium on the properties of TiO₂ nanopowders were investigated. The formation mechanism of TiO₂ microflowers was discussed. The results showed that with the increasing of carbon chain of alcohol, the diameter of TiO₂ nanopowders increased. Flowers-like TiO₂ nanostructures were produced with 0.115M SDBS. Flowers-like TiO₂ nanostructures were composed of TiO₂ cuboid nanorods, and the length, width and thickness of cuboid nanorods were 1 ~ 2 μm, 100nm and 100nm, respectively.