共查询到20条相似文献,搜索用时 31 毫秒
1.
《Synthetic Metals》2007,157(10-12):454-459
In this study, two practical methods for the facile and controlled preparation of poly(vinyl alcohol) (PVA) nanofibers containing Ag nanoparticles were investigated for use in antimicrobial applications. In the first method, PVA nanofibers containing Ag nanoparticles were successfully electrospun from PVA/silver nitrate (AgNO3) aqueous solutions after first refluxing them. The Ag nanoparticles in the PVA/AgNO3 aqueous solutions were generated by refluxing them. Interestingly, it was found that the Ag nanoparticles were also spontaneously generated during the electrospinning process. In the second method, Ag nanoparticles were generated by annealing the PVA nanofibers electrospun from PVA/AgNO3 aqueous solutions. Residual Ag+ ions and the Ag nanoparticles generated during the electrospinning process in the PVA nanofibers were diffused and aggregated into larger Ag nanoparticles during the annealing process. All of the Ag nanoparticles were sphere shaped and evenly distributed in the PVA nanofibers prepared by the two methods. 相似文献
2.
Jaewon Choi Jeongwoo Lee Jinsub Choi Dongsoo Jung Sang Eun Shim 《Synthetic Metals》2010,160(13-14):1415-1421
Herein, PEDOT:PSS/PVP nanofibers were produced by electrospinning. The presence of PEDOT:PSS in the nanofibers was confirmed by FT-Raman spectroscopy. The applied voltage-dependent diameter of PEDOT:PSS/PVP nanofibers was observed. Also, sensing behaviors of electrospun PEDOT:PSS/PVP nanofibers were explored by measuring its response upon cyclic exposure to organic vapours such as ethanol, methanol, THF, and acetone at room temperature. When PEDOT:PSS/PVP nanofibers were exposed to each solvent, the protic and aprotic solvents resulted in opposite electrical responses. These findings exhibit that electrospun PEDOT:PSS/PVP nanofibers are the promising candidate for the organic vapour sensing material. 相似文献
3.
《Synthetic Metals》2007,157(18-20):751-757
Polyaniline–Fe2O3 composites were chemically prepared by oxidative polymerization of aniline in phosphoric acid medium with ammonium persulphate as oxidant. Different ratios of aniline–Fe2O3 were taken to prepare polyaniline–Fe2O3 composites, i.e. 1:2, 1:1, 2:1. The composites were characterized by FTIR, XRD and SEM. Using the prepared composites, primer paints with acrylic binder were prepared and coated on the steel samples. The corrosion protection ability of the coating was found out by EIS method in 3% NaCl solution. It has been found that the coating with composite of 1:1 ratio of aniline:Fe2O3 is found to offer higher protection than the coating with other ratios and plain Fe2O3. 相似文献
4.
Samaneh Shahgaldi Zahira Yaakob Dariush Jafar Khadem Wan Ramli Wan Daud 《Journal of Alloys and Compounds》2011,509(37):9005-9009
The cobalt-free perovskite-oxide, Ba0.5Sr0.5Fe0.8Cu0.2O3−δ (BSFC) is a very important cathode material for intermediate-temperature proton-conducting solid oxide fuel cells. Ba0.5Sr0.5Fe0.8Cu0.2O3−δ nanofibers were synthesized for the first time by a sol-gel electrospinning. Process wherein a combination of polyvinylpyrrolidone and acetic acid was used as the spinning aid and barium, strontium, iron and copper nitrates were used as precursors for the synthesis of BSFC nanofibers. X-ray diffraction studies on products prepared at different calcination temperatures revealed a cubic perovskite structure at 900 °C. The temperature of calcination has a direct effect on the crystallization and surface morphology of the nanofibers. High porosity, and surface area, in addition to an electrical conductivity of 69.54 S cm−1 at 600 °C demonstrate the capability of BSFC nanofibers to serve as effective cathode materials for intermediate-temperature solid oxide fuel cells. 相似文献
5.
Composites with ferromagnetic nanoparticles, Fe and Fe50Ni50, dispersed in Al2O3 have been synthesized by a solution phase technique. The structure and magnetic properties of these composites with varying fractions of Al2O3 have been investigated. Both Fe and Fe50Ni50 nanoparticles are amorphous in the as-prepared state and become crystalline on heat treating with near equilibrium lattice parameters of 0.287 nm and 0.358 nm respectively. The interparticle distance increases with increasing Al2O3 from 0 wt.% to 20 wt.%. The size of Fe nanoparticles is 40 nm while the Fe50Ni50 nanoparticles are 20 nm in size. The Fe and Fe50Ni50 nanoparticles dispersed composites are found to be ferromagnetic at room temperature both in the as-prepared and heat treated conditions with clear coercive fields of 5.5–35 × 103 A m−1. The saturation magnetization increases by orders of magnitude on heat treatment, for e.g. from <1.0 emu g−1 to 143.4 emu g−1 for Fe–15 wt.% Al2O3 and 95.6 emu g−1 for Fe50Ni50–15 wt.% Al2O3. The Fe-composites exhibit a Curie transition at 1000 K while the Fe50Ni50 composites exhibit a transition at 880 K, both temperatures close to bulk values. 相似文献
6.
将聚丙烯腈(PAN)粉末配制为PAN/DMF溶液,通过静电纺丝工艺制备了PAN纳米纤维,然后依次进行预氧化、碳化处理得到纳米碳纤维;采用CO2作为活化剂制备了超大比表面积活性碳纤维。使用扫描电镜、场发射透射电镜、拉曼光谱,傅里叶红外光谱和N2吸附等手段对样品的形貌、成分和结构进行了全面表征,研究了聚合物溶液浓度和静电压对PAN纳米纤维形貌和直径的影响。活性碳纤维独特的孔结构使其作为电极材料在多种电解液中保持了较高的比容量。结果表明活化后的碳纤维的比表面积、总孔容和微孔孔容都明显增加,本研究所制备的活性碳纤维具有极高的比面积和良好的电导率,使其在超级电容器电极材料领域有着进一步的应用。 相似文献
7.
《Acta Materialia》2001,49(14):2805-2811
Fe2O3–SiO2 nanocomposites with Fe/Si molar concentrations ranging between 0.25 and 0.57 were prepared by the sol-gel route. Tetraethoxysilane and iron(III) nitrate solution in ethanol were mixed and the hydrolysis reaction was promoted by the hydration water of the salt. The sols were gelated in air and then treated at 400°C for 4 h. The effect of the gelation process on the formation of the final nanocomposites has been investigated by studing different factors, such as temperature and surface of evaporation/volume ratio of the sol. Nanoparticles of γ and/or α iron oxide phase of different size were obtained in the silica matrix depending on the gelation conditions and on the later heat treatments. γ-Fe2O3–SiO2 nanocomposites were obtained only when organic material was present into the pores of the gel silica matrix supporting their formation through a magnetite phase. At temperatures >400°C, the γ-phase begins to transform to the α-phase. 相似文献
8.
《Acta Materialia》2000,48(14):3803-3812
Carbon nanotube–metal–oxide composites (metal=Fe, Co or Fe/Co alloy; oxide=Al2O3, MgO or MgAl2O4) have been prepared by hot-pressing the corresponding composite powders, in which the carbon nanotubes, mostly single or double-walled, are very homogeneously dispersed between the metal–oxide grains. For the sake of comparison, ceramic and metal–oxide nanocomposites have also been prepared. The microstructure of the specimens has been studied and discussed in relation to the nature of the matrix, the electrical conductivity, the fracture strength and the fracture toughness. The carbon nanotube–metal–oxide composites are electrical conductors owing to the percolation of the carbon nanotubes. 相似文献
9.
纳米纤维具有极大的比表面积、可控的多孔二级结构等一系列优良特性,使其在环境保护、能源利用、催化剂、药物载体、组织工程支架材料等领域得到了广泛应用。通过静电纺技术制备的纳米纤维主要有有机纳米纤维、无机纳米纤维、以及有机/无机杂化纳米纤维3类。结合作者课题组之前的研究成果积累,综述了各种不同的静电纺有机/无机杂化纳米纤维载药体系的构建及其生物医学应用。着重介绍了如何将药物负载在无机纳米颗粒(埃洛石、锂皂石、羟基磷灰石、介孔二氧化硅等)的表面或内部并进而和高分子混纺形成双载体纳米载药纤维的过程和相关药物缓释机理,并探讨了有机/无机杂化纳米纤维载药体系的生物医学应用,尤其是在抗菌和抗肿瘤方面的治疗应用。文章最后对该领域的研究方向和前景作了展望。 相似文献
10.
采用溶胶-凝胶法与静电纺丝技术相结合制备了PVP/[Ni(NO3)2+Fe(NO3)3]复合纳米纤维,在一定温度下进行热处理,得到尖晶石结构的NiFe2O4纳米纤维。利用TG-DTA、XRD、FTIR、SEM、TEM等分析手段对样品的组成及结构进行表征。TG-DTA分析表明,PVP/[Ni(NO3)2+Fe(NO3)3]复合纳米纤维的热处理温度高于450℃以后,质量恒定,总失重率为87.8%。XRD与FTIR分析表明,热处理温度高于600℃时,复合纳米纤维已经完全转变成尖晶石结构的NiFe2O4纳米纤维。SEM分析表明,所制备的PVP/[Ni(NO3)2+Fe(NO3)3]复合纤维直径在250~300nm之间,NiFe2O4纳米纤维直径约100nm,长度大于200μm。对NiFe2O4纳米纤维的形成机理进行了探讨。 相似文献
11.
《Synthetic Metals》2007,157(18-20):784-791
Polyaniline/nano-Fe3O4 composites were prepared by a novel solids-stabilized emulsion (Pickering emulsion) route for the first time. The products were characterized by SEM, XRD, FTIR spectra and particle size analyzer. Sphere-like morphology and sub-micrometer fibers of polyaniline/nano-Fe3O4 composites were synthesized in a toluene/water emulsion stabilized by Fe3O4 nanoparticles. It was found that the morphology of the resulting PANI/nano-Fe3O4 composites depended not only on the volume ratio of toluene to water (R), but also the amount of Fe3O4 in the reaction system. A possible mechanism for the formation of the different morphologic composites has been proposed. The room-temperature conductivity of PANI/nano-Fe3O4 composites also depended not only on the volume ratio of toluene to water (R), but also the amount of Fe3O4 in the reaction system. In addition, it was found that the magnetization under applied magnetic field for the as prepared the PANI/nano-Fe3O4 composites exhibited a clear hysteretic behavior, and both MS and HC for the PANI/nano-Fe3O4 composites exhibited a decrease with decreasing the nano-Fe3O4 content. 相似文献
12.
Tanmay K. Ghorai Mukut ChakrabortyPanchanan Pramanik 《Journal of Alloys and Compounds》2011,509(32):8158-8164
Nano-particles of homogeneous solid solution between TiO2 and Fe2O3 (up to 10 mol%) have been prepared by mechanochemical milling of TiO2 and yellow Fe2O3/red Fe2O3/precipitated Fe (OH)3 using a planetary ball mill. Such novel solid solution cannot be prepared by conventional co-precipitation technique. A preliminary investigation of photocatalytic activity of mixed oxide (TiO2/Fe2O3) on photo-oxidation of different organic dyes like Rhodamine B (RB), Methyl orange (MO), Thymol blue (TB) and Bromocresol green (BG) under visible light (300-W Xe lamp; λ > 420 nm) showed that TiO2 having 5 mol% of Fe2O3 (YFT1) is 3-5 times higher photoactive than that of P25 TiO2. The XRD result did not show the peaks assigned to the Fe components (for example Fe2O3, Fe3O4, FeO3, and Fe metal) on the external surface of the anatase structure in the Fe2O3/TiO2 attained through mechanochemical treatment. This meant that Fe components were well incorporated into the TiO2 anatase structure. The average crystallite size and particle size of YFT1 were found to be 12 nm and 30 ± 5 nm respectively measured from XRD and TEM conforming to nanodimensions. Together with the Fe component, they absorbed wavelength of above 387 nm. The band slightly shifted to the right without tail broadness, which was the UV absorption of Fe oxide in the Fe2O3/TiO2 particle attained through mechanochemical method. This meant that Fe components were well inserted into the framework of the TiO2 anatase structure. EPR and magnetic susceptibility show that Fe3+ is in low spin state corresponding to μB = 1.8 BM. The temperature variation of μB shows that Fe3+ is well separated from each other and does not have any antiferromagnetic or ferromagnetic interaction. The evidence of Fe3+ in TiO2/Fe2O3 alloy is also proved by a new method that is redox titration which is again support by the XPS spectrum. 相似文献
13.
The zinc titanate composite nanofibers were prepared using electrospinning method combining sol–gel process followed by calcining the precursor PVP/Zn(CH3COO)2–Ti(OC4H9)4 fibers under air in the temperature range of 400–700 °C. The nanofibers were characterized by thermal field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), thermal gravimetric and differential thermal analysis (TG–DTA). FE-SEM micrographs indicated that the surfaces of the nanofibers are uniform and smooth and the diameter of the fiber decreasing as the calcination temperature increasing. It is also found that ZnO–TiO2 ceramic fibers including ZnTiO3, Zn2TiO4 and rutile phase were synthesized by calcining the precursor PVP/Zn(CH3COO)2–Ti(OC4H9)4 composite fibers at 700 °C. 相似文献
14.
S. A. Gridnev Yu. E. Kalinin A. V. Kalgin E. S. Grigor’ev 《Protection of Metals and Physical Chemistry of Surfaces》2009,45(5):583-587
The magnetoelectric (ME) effect in two- and three-layered composites made up of polarized ceramic plates of lead zirconate-titanate
PbZr0.53Ti0.47O3 (PZT) and manganese-zinc ferrite Mn0.4Zn0.6Fe2O4 (MZF) has been studied. Dependences of the transverse ME voltage coefficient (α31) on the magnetostrictive layer thickness and the magnetic field intensity and frequency have been established. The mechanical
coupling coefficient of the composite plates has been estimated. Results obtained for two-layered PZT-MZF structures have
been analyzed using the method of efficient medium parameters. 相似文献
15.
In-Jin Shon Kwon-Il Na Jung-Mann Doh Hyun-Kuk Park Jin-Kook Yoon 《Metals and Materials International》2013,19(1):99-103
Nanopowders of Fe, Al and Fe2O3 are fabricated by high energy ball milling. Using the pulsed current activated sintering method, the densification of nanocrystalline Fe2Al5 and Al2O3 reinforced Fe2Al5 composites were simultaneously synthesized and consolidated within two minutes from mechanically activated powders. The advantage of this process is that it allows very quick densification to near theoretical density and prohibition of grain growth in nanostuctured materials. Nanocrystalline materials have received much attention as advanced engineering materials with improved physical and mechanical properties. As nanomaterials possess high strength, high hardness, excellent ductility and toughness, undoubtedly, more attention has been paid to the application of nanomaterials. Not only the hardness but also the fracture toughness of the Fe2Al5-Al2O3 composite was higher than that of monolithic Fe2Al5 due to the addition of the hard phase of Al2O3 and the crack deflection by Al2O3. 相似文献
16.
Electric transport and magnetoresistance characteristics were investigated for Fe3O4-x Fe(x=0, 10, 20 wt.%) samples and Fe3O4-α-Fe2O3 samples sintered at 500°C. For composition dependence of Fe3O4-x Fe samples, the largest room temperature MR, 3.3% at 10 kOe, was obtained from a Fe3O4-10 Fe sample. For the surface heat treatment dependence of Fe3O4 powders, the largest room temperature MR, 4% at 10 kOe, was obtained from a Fe3O4-α-Fe2O3 sample sintered with Fe3O4 powders heated at 200°C in air. It was found that these enhanced MR ratios always appear together with the appropriate excess
resistance which is regarded as the tunneling barrier. These enhanced MR ratios of Fe3O4-10 Fe and Fe3O4-α-Fe2O3 samples can be explained by the increased interparticle contact sites and the appropriate thickness of α-Fe2O3, respectively. 相似文献
17.
《Acta Materialia》2008,56(13):3260-3265
A novel kind of magnetic and mesoporous bioactive glass (MMBG) composite with Fe3O4 nanoparticles confined and dispersed in ordered mesoporous glass matrices has been prepared by a one-pot synthesis route of simultaneous evaporation-induced self-assembly of Ca, P, Si and Fe sources and subsequent reduction in an H2 atmosphere. The MMBG composites exhibit the type IV isotherm curve with a well-defined step P/P0 between 0.4 and 0.8. Ibuprofen storage and release experiments with these composites show adjustable loading amounts from 199 to 420 mg g−1 and a sustained drug release property. A superparamagnetic behavior was identified and the saturation magnetization of the bioactive glass composites was found to increase at increased loading amounts of Fe species. The magnetic and mesoporous bioactive glass composites are believed to be potentially applicable for selectively targeted drug delivery and hyperthermia treatment of bone tumors. 相似文献
18.
Deuk Yong Lee Myung-Hyun Lee Nam-Ihn Cho Bae-Yeon Kim Young-Jei Oh 《Metals and Materials International》2010,16(3):453-457
Barium titanate (BaTiO3, BT) nanofibers with a diameter range of 160 nm to 300 nm were prepared by drying electrospun BT/polyvinylpyrrolidone (BT/PVP)
composite fibers for 1 h at 80 °C in vacuum with a subsequent calcination in air for 1 h at a temperature range of 650 °C
to 750 °C. The morphology and crystal structure of calcined BT nanofibers were characterized with the aid of XRD, FT-IR, SEM,
and TEM. The XRD and FR-IR measurements confirm that BT nanofibers with a diameter of about 160 nm and a tetragonal perovskite
structure were present in the electrospun fibers after calcination for 1 h at 750 °C. The FR-IR analysis of the BT fibers
reveals that the intensity level of the O-H stretching vibration bands (at 3430 cm−1 and 1425 cm−1) become weaker as the calcination temperature is increased and that a broad band at 570 cm−1, which represents the Ti-O vibration, appears sharper and narrower after calcination at 750 °C due to the formation of metal
oxide bonds. In contrast, BT fibers prepared by a refluxing process in a nitrogen atmosphere show a dramatic change in crystal
structure: the tetragonal structure changes to a cubic perovskite structure, probably due to the suppression of carbonate
contamination. Thus, the calcination temperature and atmosphere appear to have a significant influence on the crystal structure
of BT. 相似文献
19.
通过静电纺丝法制备中空多孔的NiO/SnO2复合纳米纤维,在复合纤维表面装饰碳纳米管,在此基础上制备气敏传感器器件.利用TGA确定了复合材料热分解温度和热处理工艺;利用SEM、XRD、TEM、XPS分别对复合材料的形貌、结构、尺寸、表面成分进行了表征.使用WS-30A气敏元件测试仪对气敏元件响应进行了测试.结果 表明,... 相似文献
20.
Cristina Della Pina Michele Rossi Anna Maria Ferretti Alessandro Ponti Massimiliano Lo Faro Ermelinda Falletta 《Synthetic Metals》2012
Polyaniline/Fe3O4 nanocomposites were prepared by a one-pot synthesis using N-(4-aminophenyl)aniline as the reagent, molecular oxygen or hydrogen peroxide as the oxidizing agents in the presence of Fe3O4 nanoparticles (NPs) in powder and ferrofluid form. Both magnetic NPs in powder and ferrofluid form showed similar catalytic behaviour. The catalytic effect is particularly evident when molecular oxygen was used as the oxidizing agent. However, concerning the morphological aspects, only the composites prepared in the presence of ferrofluid-type Fe3O4 NPs showed a preferential morphology of nanorods (between 30 and 110 nm in diameter). All the composites are superparamagnetic at room temperature but at low temperature they are in a blocked state. Inter-particle interactions significantly affect the magnetic properties of the composites. The electrical conductivity of the composites is about 10−2 S cm−1, in agreement with the values obtained for polyaniline prepared by chemical route. A mechanism of the nanorods formation is proposed. 相似文献