In2O3纳米陶瓷纤维无纺布的静电纺丝制备及气敏特性研究

采用溶胶-凝胶法结合静电纺丝技术制备了直径20～60 nm的超细氧化锢(In2O3)纳米陶瓷纤维及纳米陶瓷纤维无纺布.采用XRD,IR,SEM,HR-TEM,TGA等分析方法对纳米纤维的形貌和显微结构进行了表征,并研究了其气敏特性.由700℃下煅烧的该超细In2O3纳米纤维所制备的气敏元件具有较好的反应和选择性,对甲醛...     

氧化铟纳米棒的气敏特性

以非离子表面活性剂烷基苯酚聚氧乙烯醚OP-10为形貌控制剂合成In2O3纳米棒.用热重-差示扫描量热法、X射线衍射和透射电镜对In2O3纳米棒的热分解过程、晶体结构和微观形貌进行表征.对纳米棒制得的气敏元件进行气敏性能测试,同时用扫描电子显微镜及比表面积和孔隙度分析仪对元件的表面形貌和材料的介孔结构进行了分析.结果表明:制得的In2O3为立方晶型的纳米棒,直径约20 nm,长度约120 nm.与In2O3纳米颗粒气敏性能相比,In2O3 纳米棒对三甲胺具有更高的灵敏度和选择性.用In2O3纳米棒制的气敏元件对三甲胺在一定的浓度范围内的灵敏度与浓度呈现良好的双对数线性关系.棒状材料中形成的大量介孔对气敏性能的提高有着重要的作用.     

溶胶–凝胶法制备碳纳米管-In_2O_3纳米复合材料及其气敏性

以碳纳米管（carbon nanotubes,CNT）为模板,在超声波辅助条件下,利用溶胶–凝胶法合成CNT–In2O3纳米复合粉体,用该复合粉体制备CNT–In2O3气敏元件。借助X射线衍射、透射电子显微镜、傅立叶变换红外光谱仪和能量色散谱仪对产物进行表征,研究了CNT–In2O3气敏元件的气敏性。结果表明：CNT–In2O3纳米复合粉体是一种由In2O3纳米颗粒均匀包裹在直径约为20～30nm的碳纳米管上的纳米复合材料。CNT–In2O3气敏元件在低温对NO2有较高的灵敏度,该元件对NO2的灵敏度高于纯In2O。当CNT和InC13·4H2O的摩尔比为3：10时,CNT–In2O3气敏元件对NO2的灵敏度最大,且灵敏度随NO2浓度的增大而增大。该气敏元件在200℃时对NO2的响应时间为10s,恢复时间为70s。     

氧化铟纳米粉体的微乳液合成及其气敏特性

用微乳液法合成了纳米In2O3粉体,浸渍法制备了5％(in mass)La2O3掺杂In2O3。利用X射线衍射、透射电镜对合成产物进行了结构表征。采用静态配气法对氧化铟气敏元件的气敏特性进行了测试。结果表明：微乳液法合成的氧化铟经600℃,5h煅烧后,颗粒尺寸约为30nm,且分布均匀。氧化铟气敏元件对汽油、酒精、甲醛等有机蒸气具有较高的检测灵敏度,但选择性不好。氧化镧掺杂后,不同温度工作时,氧化铟分别对汽油、酒精有较好的选择性,且响应恢复快。     

（急）In2O3-CuO的制备及其光活化下的室温甲醛气敏性能

以InCl3.4H2O和Cu(NO3)2.3H2O为原料,尿素为沉淀剂,采用水热法制备In2O3-CuO复合材料。通过微观结构表征和宏观气敏特性相关联,探究紫外光活化In2O3-CuO复合材料的气敏性能与传感机制。研究结果表明,In2O3-CuO复合材料在375 nm 紫外光照射室温（25℃）条件下对50 ppm甲醛气体的灵敏度为298,与纯In2O3（2.4）相比灵敏度提高124倍,气敏性能的巨大提升归因于In2O3与CuO形成的p-n异质结,协同光活化条件下异质结界面产生的光生电子-空穴与氧物种（O2和O2-）间建立了氧的光活化吸附－解吸循环,使得室温下材料的气体吸附－解吸过程和表面反应增强。为光敏材料的应用和室温气体传感材料的设计提供了新的策略。     

静电纺丝法合成Fe掺杂一维NiO纳米纤维及其丙酮气敏性能的研究

采用静电纺丝工艺制备出不同Fe掺杂比例的一维NiO纳米纤维粉体。研究了不同Fe元素掺杂对一维NiO纳米纤维粉体的微观形貌、结构以及丙酮气敏性能的影响，测试结果表明：当Fe元素掺杂浓度较低时，Fe掺杂一维NiO纳米纤维粉体晶体结构未发生变化，均为立方相结构。不同比例Fe元素掺杂NiO粉体均具有良好的一维形貌。与一维NiO纳米纤维纳气敏性能相比，Fe掺杂Ni O纳米纤维粉体的最佳气敏工作温度更低，灵敏度更高，气体选择性相应更好，当Fe元素掺杂量为4%时，一维NiO纳米纤维材料对丙酮气体具有最佳的气敏特性。工作温度为300℃时，纳米纤维对100 ppm丙酮气体灵敏度达到23.2，随着丙酮气体浓度增加，Fe掺杂一维NiO纳米纤维粉体的气敏响应灵敏度呈上升趋势。一维NiO纳米纤维气敏性能的改善可归因于Fe元素掺杂促使NiO粉体的缺陷增多，可以为气敏反应提供更多的反应点，从而提高了其气敏性能。     

纳米Fe2O3的制备与气敏性质的研究

报道了纳米氧化铁的制备工艺，采用沉淀法、溶胶凝胶法制备了纳米α-Fe2O3、γ-Fe2O3粉体，用热重－差热分析（TG－DTA）、X射线衍射（XRD）、透射电镜（TEM）和二次粒度分布对粒子进行表征，并制作了气体敏感元件。讨论了纳米氧化铁的制备工艺对气敏性质的影响。     

In2O3基纳米材料气敏性能研究综述

In2O3半导体纳米材料由于具有较高的响应灵敏度、较快的响应-恢复时间,是气敏领域的明星材料,得到了广大研究者的青睐。然而,In2O3气敏材料由于化学组份单一往往催化能力有限,气敏性能不太理想(灵敏度较低、相应的恢复时间较长、功耗较高),严重限制了其在日常生产生活中的应用。实验证明:对单一的气敏材料修饰改性可以有效提升材料的气敏性能。国内外广大研究者相继对In2O3进行了大量的研究工作并取得了显著的成果。综述了In2O3气体传感器最新的研究进展,对近几年In2O3半导体纳米材料发展存在的问题及改性方法进行概括,并对以后的发展进行了展望。     

水热法制备ZrO_2纳米微晶及对乙醇和丁烷气敏性研究

用水热法制备 Zr O2 纳米微晶的平均尺寸为直径 5 nm,长 7.5 nm。由 X射线衍射确认晶相为单斜相。并对其形状和大小进行了透射电镜和激光散射分析 ,结果表明 Zr O2 纳米粒子在水溶液中存在软团聚 ,团聚体平均尺寸约 90 nm。着重研究了 Zr O2 纳米微晶对乙醇及丁烷的气敏性能 ,结果表明用纳米级 Zr O2 粒子制备的气敏元件对乙醇和丁烷有好的气敏性。并且随着纳米粒子尺寸降低 ,对气体敏感性增强     

Fe掺杂ZnO纳米纤维的制备及其乙炔气敏性能的研究

采用静电纺丝法制备了Fe掺杂ZnO纳米纤维,研究了不同浓度Fe掺杂对ZnO纳米纤维的形貌、晶体结构及乙炔气敏性能的影响。结果表明:Fe掺杂对其结构及形貌未产生影响,Fe掺杂明显提高了ZnO纳米纤维的气敏性能,Fe掺杂量为6%的ZnO纳米纤维对乙炔气体具有最佳的气敏特性,工作温度为300℃时,粉体对1000 ppm HCHO气体灵敏度达到74.61,随着乙炔气体浓度增大,Fe掺杂ZnO纳米纤维粉体的灵敏度呈上升趋势。这主要是由于Fe元素掺杂使ZnO的缺陷增多,为气敏反应提供更多的活化点,从而提高了气敏性能。     

Enhancing dielectric properties of barium titanate macrofibers

The motivation of this work was to improve the dielectric properties of BaTiO₃ (BT) macrofibers by mixing BT nanofibers and commercial BT powder. BT nanofibers were fabricated via electrospinning synthesis. The calcined electrospun nanofibers were chopped and mixed with BT powder and converted in to a thermoplastic feedstock for extrusion of ceramic macrofibers with a diameter of 500 μm. The electromechanical properties of the BaTiO₃ macrofibers were investigated by varying calcination temperature of the nanofibers. For both nano and macro fibers, microstructure and phase composition was investigated by SEM and XRD. It could be observed that an increase in calcination temperature of the nanofibers enhanced the final electromechanical properties of the sintered macrofibers. The relative permittivity increased almost twice, the remanent polarisation increased about 4 times and the strain almost increased 10 times with the addition of calcined nanofibers to macrofibers.     

Preparation and Xylene‐Sensing Properties of Co3O4 Nanofibers

Co₃O₄ nanofibers were prepared by an electrospinning method and characterized by differential thermal and thermal gravimetric analyzer (DTA‐TGA), X‐ray diffraction (XRD), Fourier Transform Infrared Spectrometer (FT‐IR), and scanning electron microscopy (SEM). Xylene‐sensing properties of the as‐prepared nanofibers were also investigated in detail. The results showed that the morphology of the as‐prepared fibers was largely influenced by the calcination temperature. The Co₃O₄ nanofibers calcined at 500°C exhibited the highest response to xylene in a wide concentration range. Moreover, Co₃O₄ nanofibers calcined at 500°C also exhibited good selectivity, fast response (15 s) and recovery (22 s) rate at a low operating temperatures of 255°C. These properties make the fabricated nanofibers good candidates for xylene detection.     

Microstructural differences between electrospun alumina borate nanofibers prepared by solutions with different PVP contents

Alumina borate nanofibers were fabricated by electrospinning combined with sol-gel method using aluminum acetate (Al(OH)₂(OOCCH₃)·1/3H₃BO₃, stabilized with boric acid) and polyvinyl pyrrolidone (PVP) as raw materials. As-spun composite nanofibers were electrospun from the spinning solutions prepared with different PVP contents. The as-spun nanofibers were calcined at 1000 ℃ and the microstructures of the calcined nanofibers were investigated. The results showed that with the content of PVP increased, the diameters of the alumina borate nanofibers increased, and the temperatures at which the Al₄B₂O₉ phase formed and Al₄B₂O₉ transformed to Al₁₈B₄O₃₃ also increased. However, the crystallinity of the calcined nanofibers decreased with the increase of the PVP content. The grains became smaller and more uniform due to the increasing amount of voids and cracks generated by the decomposition of PVP.     

Controlling the Diameter of Electrospun Yttria‐Stabilized Zirconia Nanofibers

This work reports the precise diameter control of electrospun yttria‐stabilized zirconia (YSZ) nanofibers from 200 to 900 nm after calcination. Fabricated YSZ nanofibers showed porous nanocrystalline structures with high aspect ratios of more than 500:1 and high surface‐to‐volume ratios with a specific surface area of 43.32 m²/g. The diameter of the YSZ nanofibers increased with the viscosity of the precursor solution, which was controlled by the concentrations of either polymers (polyacrylonitrile) or ceramic precursors (YSZ). We present a modified correlation between the diameter of a nanofiber and the synthetic conditions, as the observed behavior for calcined ceramic nanofibers deviated from the expected behavior. Our results demonstrate a modified but simple approach to fabricate ceramic nanofibers with desired diameters, providing a new design guideline for many electrochemical applications.     

Al2O3-TiCN的制备和性能

用气压烧结的方法制备了Al2O3-TiCN复相陶瓷。测量了其物理性能，用扫描电镜观察了其断口形貌，并分析了烧结温度对力学性能的影响，确定了最佳烧结温度。     

Ar plasma treatment on ZnO–SnO2 heterojunction nanofibers and its enhancement mechanism of hydrogen gas sensing

In this study, ZnO–SnO₂ heterojunction nanofibers were fabricated using electrospinning and treated by Ar plasma. The post treatment demonstrated the ability to regulate adsorbed oxygen of nanofibers and thus affecting the gas sensing performance. The results revealed that the gas sensing performances increased with the increase of plasma treatment time at first, then showed a downward trend. The setting for the best H₂ gas performance was 20 min of plasma treatment, under which the response of the sample was 80% higher and the response time was two thirds shorter than those of the untreated sample. The explanation can be that appropriate plasma treatment can increase the oxygen vacancy on the surface of heterojunction nanofibers as well as the resistance modulation range in the air; however, excessive plasma treatment can result in the reduction of the resistance modulation range in the air by reducing the metal oxide to metal.     

Gd~(3+)掺杂TiO_2纳米纤维的制备、表征及其光催化性能

采用静电纺丝技术并结合溶胶-凝胶方法制备TiO2和TiO2/Gd2O3纳米纤维,采用差热-热重分析(TG-DTA)?场发射扫描电镜(FE-SEM)、红外光谱(FTIR)、X射线粉末衍射(XRD)对材料进行表征,通过亚甲基蓝光降解反应研究其催化性能。结果表明,掺杂Gd3+可以强烈抑制TiO2由锐钛矿相向金红石相的转变,抑制晶粒生长,减少晶粒尺寸;Gd3+掺杂TiO的纳米纤维对亚甲基蓝的光催化活性明显提高。     

Fabrication and Piezoelectric Property of BaTiO3 Nanofibers

BaTiO₃ (BTO) nanofibers were fabricated by sol–gel combined with electrospinning method. The effects of the concentration of acetic acid and sintering temperatures on the crystal phase and microstructure of the samples were investigated by scanning electron microscopy, X‐ray diffraction, and transmission electron microscopy (TEM). BTO nanofibers with improved surface morphology were obtained as the ethanol to acetic acid ratio (E/A) was 8:3. The fibers calcined at 750°C for 2 h exhibited good morphology and crystallization. TEM studies revealed that the BTO nanofibers were polycrystalline, with diameters being on the order of hundreds nanometer, where the existence of domains offered proof of ferroelectric structure. The ferroelectric domains and piezoresponse of BTO nanofibers were characterized by piezoresponse force microscopy. The calculated d₃₃ was 20 pm/V at maximum strain amplitude.     

Flexible,hydrophobic SiC ceramic nanofibers used as high frequency electromagnetic wave absorbers

In this paper, flexible hydrophobic SiC ceramic nanofibers have been successfully fabricated via electrospinning and subsequent high temperature heat treatment. The synthesized SiC ceramic nanofibers show excellent flexibility without any breakage even under a bending angle of 142.6°, and high hydrophobicity with a water contact angle of 149.05°. The SiC nanofibers exhibit excellent electromagnetic (EM) wave absorption properties with an effective absorption bandwidth (reflection loss (RL) <−10 dB, 90% EM wave absorbed) of 4–18 GHz. The maximum reflection loss of SiC ceramic nanofibers reaches −19.4 dB at 5.84 GHz. In addition, the nanofibers are environmentally stable in 2 mol/L NaOH solution for 2 h and high temperature of 500 °C in air atmosphere. The excellent EM wave absorption performance, flexibility, hydrophobic properties, corrosion resistant properties in alkali environment and high temperature stability make SiC ceramic nanofibers to be a potential candidate for EM wave absorption used in harsh environment.     

Fabrication and characterization of new bulky layer mixed metal oxide ceramic nanofibers through two nozzle electrospinning method

New bulky layers of metal mixed ceramic nanofibers were fabricated through two-nozzle electrospinning method followed by calcination. Solutions of PAN in DMF with various concentrations were prepared as: 11, 12, 13, 14, and 15 wt% to which the constant amounts of 2.1 g of Aluminum acetate, 0.3 g of Copper acetate and 0.3 g of Boehmite nanoparticles were added. A stepwise calcination process was utilized to obtain the ceramic nanofibers. The nanofibers were characterized by FTIR spectroscopy, TG-DTA, XRD, SEM and EDS techniques. The formulation with 12 wt% of PAN in DMF was proved to be the optimum spinable sample. The average diameter of as spun nanofibers was detected as 568 nm, which decreased to 181 nm after calcination and thermal degradation. Ceramic nanofibers were composed of CuO, Al₂O₃ and Cu₂Al₄O₇ phases. The average density of the sample was about 0.090 (g/cm³) and the porosity of the mat was 94.5% and thus, production of a 3D structure may be claimed. The ceramic nanofibers performed well as catalyst in the C-C coupling reaction (Suzuki reaction) by facilitating the synthesis of biaryl compound from aryl iodide in 20 min with isolated yield of 89% only by using 15 mg of ceramic nanofibers as the nano catalyst.