Institutional Repository of Ningbo Institute of Material Technology & Engineering, CAS

    Surfactant-free fabricationof α-Fe2O3 structures with flower-like morphology inaqueous solution

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    Monodispersehematite(α-Fe2O3) nanostructures with flower-like morphology were obtained by a simple forced hydrolysis and thermal decomposition method without the assistance of any template or organic surfactant.The microstructure of the final flower-like particles was characterized in detail by transmission electron microscopy and selected area electron diffraction,which showed the composite structure of the particle“core”.Electron diffraction patterns obtained forsections located on the“leaf” of the particles were consistent with hematite single crystals,whereas those obtained for the middle of the particle showed additional spots,due to the presence of goethite in the particle core.Fourier transform infrared spectroscopy and X-ray diffraction also confirmed the presence of goethite phase in the particle.A mechanism based on nucleation–aggregation–recrystallization,which speculated that the goethite precipitates first and then hematite heterogeneously nucleates on goethite particles,was proposed.Monodispersehematite(α-Fe2O3) nanostructures with flower-like morphology were obtained by a simple forced hydrolysis and thermal decomposition method without the assistance of any template or organic surfactant.The microstructure of the final flower-like particles was characterized in detail by transmission electron microscopy and selected area electron diffraction,which showed the composite structure of the particle“core”.Electron diffraction patterns obtained forsections located on the“leaf” of the particles were consistent with hematite single crystals,whereas those obtained for the middle of the particle showed additional spots,due to the presence of goethite in the particle core.Fourier transform infrared spectroscopy and X-ray diffraction also confirmed the presence of goethite phase in the particle.A mechanism based on nucleation–aggregation–recrystallization,which speculated that the goethite precipitates first and then hematite heterogeneously nucleates on goethite particles,was proposed

    Effect of Microstructures on the Phase Transition Behavior of P(CL-GL)-PEG-P(CL-GL) Triblock Copolymer Aqueous Solutions

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    Amphiphilic poly[(ε-caprolactone)-co-glycolide]-block-poly(ethylene glycol)-block-poly[(ε-caprolactone)- co-glycolide) [P(CL-GL)-PEG-P(CL-GL)] triblock copolymers with different average lengths of caproyl sequences (LCL) were synthesized by ring-opening polymerization at different temperatures. A 25% aqueous solution of the copolymer with LCL=11.0 formed a gel, owing to strong crystallinity-induced hydrophobicity at low temperature, and underwent a gel-sol transition (UCST behavior) when the temperature was increased to 40℃. In contrast, the solution of copolymer with LCL=6.7 underwent a sol-gel transition (LCST behavior) due to micelle aggregation. However, a clear sol-turbid sol phase transition was observed for the copolymer with more random microstructures (LCL=5.2).Amphiphilic poly[(ε-caprolactone)-co-glycolide]-block-poly(ethylene glycol)-block-poly[(ε-caprolactone)- co-glycolide) [P(CL-GL)-PEG-P(CL-GL)] triblock copolymers with different average lengths of caproyl sequences (LCL) were synthesized by ring-opening polymerization at different temperatures. A 25% aqueous solution of the copolymer with LCL=11.0 formed a gel, owing to strong crystallinity-induced hydrophobicity at low temperature, and underwent a gel-sol transition (UCST behavior) when the temperature was increased to 40℃. In contrast, the solution of copolymer with LCL=6.7 underwent a sol-gel transition (LCST behavior) due to micelle aggregation. However, a clear sol-turbid sol phase transition was observed for the copolymer with more random microstructures (LCL=5.2)

    含氮杂环的新型聚酰亚胺的合成

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    Fabrication of superhydrophobic surfaces on aluminum

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    A superhydrophobic surface was prepared on aluminum substrate. Anodization and low-temperature plasma treatment were used to create micro-nano-structure and subsequently trichlorooctadecyl-silane modified the rough surface. The result shows that the water static contact of the aluminum surface after anodization and modification by trichlorooctadecyl-silane reaches to 152.1°. A rougher surface with some micro-nano-pores and small mastoids along the edges of pores was generated when low-temperature plasma treatment was applied to anodized aluminum film, resulting in water static contact angle up to 157.8°.A superhydrophobic surface was prepared on aluminum substrate. Anodization and low-temperature plasma treatment were used to create micro-nano-structure and subsequently trichlorooctadecyl-silane modified the rough surface. The result shows that the water static contact of the aluminum surface after anodization and modification by trichlorooctadecyl-silane reaches to 152.1°. A rougher surface with some micro-nano-pores and small mastoids along the edges of pores was generated when low-temperature plasma treatment was applied to anodized aluminum film, resulting in water static contact angle up to 157.8°

    Enhancement of Glass-forming Ability of CoFeBSiNb Bulk Glassy Alloy with Good Soft-magnetic Properties

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    The effect of B and Si concentration ratio on the glass-forming ability (GFA) of Co46Fe20B22+xSi6-xNb6 (x=0–2) glassy alloys was investigated. By copper mold casting, bulk glassy alloys of Co46Fe20B22+xSi6-xNb6 with diameters up to 4.5 mm were synthesized in the compositions of x=1. The additions of 23at% B combined with 5at% Si was found to be effective for the extension of the supercooled liquid region (∆Tx) defined by the difference between glass transition temperature (Tg) and crystallization temperature (Tx). The ∆Tx value is 51 K for the Co46Fe20B22Si6Nb6 alloy, and increases to 55 K for the Co46Fe20B23Si5Nb6 glassy alloy. In addition, this glassy alloy exhibits a highly reduced glass transition temperature (Tg/Tl) of 0.64 and in the compositions of x=1 was found to be in approaching alloy to a eutectic point. Large ∆Tx, high Tg/Tl and in approaching alloy to a eutectic point enabled us to prepare the Co46Fe20B23Si5Nb6 bulk glassy alloy successfully with a diameter of 4.5 mm. In addition to high glass-forming ability, the bulk glassy alloys exhibit excellent soft-magnetic properties, i.e., high saturation magnetization of 0.63–0.69 T, low coercive force of 1.17–2.35A/m, high effective permeability at 1 kHz of 1.36–2.65×104. The mechanisms for the high glass-forming ability and excellent soft-magnetic properties of the Co44Fe20B22+xSi6-xNb6 (x=0–2) glassy alloys are discussed

    Magnetocaloric effect in NaZn13-type La(1-)PrxFe(11.44)Si(1.56) melt-spun ribbons

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    The influence of Pr content on structure, magnetic properties, and magnetic entropy changes of La1-xPrxFe11.44Si1.56 was investigated. X-ray diffraction analysis showed that the 1: 13 phase with cubic NaZn13-type structure was obtained by a short time annealing (1300 K and 3 h) in melt-spun ribbons, which in contrast requires much longer time annealing at high temperature to develop in the bulk alloy. The field-induced first-order transition was observed in the as-annealed ribbons, leading to the large magnetic entropy changes. The maximum magnetic entropy changes under a magnetic field of 5 T were about 14.3, 19.2, and 19 J/kg K for the ribbons with x=0, 0.1, and 0.2, respectively. (C) 2010 American Institute of Physics

    Controlled synthesis of mesoporous carbon modified by tungsten carbides as an improved electrocatalyst support for the oxygen reduction reaction

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    Mesoporous carbon was modified with tungsten carbides by the carbothermal hydrogen reduction of a layer of chemisorbed 1:12 phosphotungstic anions (PW12O403-) on carbon surfaces. Depending on the temperature of carbothermal treatment, different tungsten species, i.e., W, W2C, WC, were formed on the carbon matrix. No significant changes in both surface areas and mesostructures were observed during the formation of various tungsten species on carbon surfaces under high-temperature conditions. A uniform dispersion of Pt nanoparticles (1-6 nm) can be achieved via nanoconfinement on the surfaces of both mesoporous carbon and tungsten carbide-modified mesoporous carbon. Pt nanoparticles supported on mesoporous carbons modified with tungsten carbide (Pt/WC-C) exhibit enhanced electrocatalytic activities relative to the control, in which mesoporous carbons without carbide modification were directly used as a support (Pt/C). In addition, both enhanced thermal stability and good electrochemical stability were observed for the Pt/WC-C electrocatalyst. Published by Elsevier B.V

    一种原位合成纳米氧化锡/碳纳米管复合材料的方法

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    本发明公开了一种原位合成纳米氧化锡/碳纳米管复合材料的方法,它主要以无机锡盐、碳纳米管和碱源为原料,实验流程主要包括前驱体制备、水热反应、沉淀物洗涤干燥等步骤,其主要优点在于:采用水热法实现了纳米氧化锡在碳纳米管表面的原位沉积和生长,所得SnO2纳米粒子粒径小且均匀(小于10nm),结晶良好,均匀包覆在碳纳米管的表面,与碳纳米管结合紧密,该复合材料在气敏传感器材料、锂离子电池的阳极材料等方面具有潜在的应用前景,本方法没有添加任何表面活性剂,原料简单易得,工艺简单无污染,制备周期短,反应条件温和,成本低,适宜规模化生产,是一种环境友好型的合成方法
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