聚苯胺纳米线阵列的电化学组装研究

利用二次氧化法制备了多孔阳极氧化铝模板,通过控制电位聚合技术在阳极氧化铝模板内组装了聚苯胺纳米线阵列。采用扫描电子显微镜、透射电子显微镜和能谱仪等检测技术对填孔过程和阵列的形貌、结构进行分析和表征。结果表明,苯胺在纳米孔中的聚合过程经历四个阶段,填孔终止时间控制为第二阶段结束时间。阳极氧化铝模板中苯胺聚合适宜的电位为1.0V,pH为2.5。聚苯胺纳米线的直径均匀,约为70nm,与模板孔径基本一致,为非晶结构。     

磁性纳米线阵列的制备与应用

介绍了以多孔氧化铝(AAO)和刻蚀高聚物为模板制备磁性纳米线阵列的方法,包括溶胶-凝胶法、化学沉积法和电沉积法等.结合磁性纳米线的研究现状,展望了磁性纳米线阵列在磁记录、巨磁电阻、量子磁盘和高密度磁存储等方面的应用前景.     

Ni_(79)-Fe_(21)合金纳米线的电化学制备与表征

以多孔氧化铝为模板,采用控电位沉积方法制备了Ni-Fe纳米线及其阵列。能谱分析表明,纳米线组成为Ni79-Fe21。X-射线衍射测试表明,Ni-Fe纳米线呈面心立方Ni固溶体结构。磁滞回线测试表明,控电位制备的Ni-Fe纳米线阵列具有良好的软磁性能,500℃退火处理后,Ni-Fe合金纳米线具有硬磁性。     

沉积液pH值对Fe纳米线阵列磁性影响的研究

采用脉冲直流电化学沉积的方法,通过调节沉积液的pH值在氧化铝模板中制备了一系列的不同结晶取向的Fe纳米线阵列。随着pH值由2.8增大到5.5,Fe纳米线逐渐从多晶Fe转变为具有不同择优取向的Fe纳米线,并在pH值为4.3时,获得了具有(110)取向的单晶纳米线阵列。通过对纳米线阵列磁性研究发现,Fe纳米线取向性的调控能有效调控纳米线阵列的磁性能。在沉积液pH值为3.4时,所制备的Fe纳米线具有(200)择优取向,此时纳米线阵列的磁晶各向异性与形状各向异性均沿纳米线的生长方向,纳米线取得了最大的垂直矫顽力1967 Oe。     

AAO模板法自组装磁性纳米线阵列及其超顺磁性

高纯铝片在草酸溶液中经直流2次阳极氧化,得到多孔氧化铝(AAO)模板。通过扩孔、缩孔和脱模实现对模板的性能优化。通过交流沉积的方法,在AAO模板内自组装Fe磁性纳米线,形成Fe纳米点阵。扫描电子显微镜(SEM)和透射电子显微镜(TEM)图像分析表明,纳米线粗细均匀,长径比约为100。单根Fe纳米线的TEM衍射花样表明其具有单晶结构。振动样品磁强计(VSM)对纳米线的宏观磁性测量可知Fe纳米线的易磁化方向均沿线长轴方向,Fe的退磁场计算表明阵列中纳米线之间存在着磁相互作用减小了退磁场的作用。Fe纳米线阵列的Mossbauer谱表现出超顺磁性,可能是来源于组成纳米线的小晶粒的超顺磁性。     

模板法组装Ag纳米线阵列及其微结构

以多孔阳极氧化铝(AAO)作为模板,利用直流电沉积法,在AAO模板孔洞中成功组装了Ag纳米线阵列。扫描电子显微镜(SEM)分析表明,Ag纳米线的长度分布十分均匀,其长度随着沉积时间的延长而线性增长,生长速度约为5μm/h。透射电子显微镜(TEM)表明,Ag纳米线粗细均匀,直径约为200 nm。选区电子衍射(SAED)分析表明,所得Ag纳米线具有多晶结构。     

电沉积制备碲化铋纳米线阵列及其表征

先采用0.3 mol/L草酸溶液在0°C、8.9 mA/cm2下对纯铝板进行二次阳极氧化,制得氧化铝多孔膜(AAO),随后以AAO为模板,采用直流电沉积法制得Bi2Te3纳米线阵列。镀液组成和工艺条件为:Bi3+0.007 5 mol/L,2HTeO+0.001 25 mol/L,3NO-1 mol/L,温度0°C,pH 0.1,时间2 h。研究了沉积电位对沉积过程的电流变化以及纳米线的Te含量、形貌和结构的影响,得到最佳沉积电位为1.4 V。在1.4 V下沉积所得纳米线结构致密、连续,孔径约为90 nm,与AAO的孔径一致。     

氧化镍纳米线的制备及光电性能研究

通过电沉积法在阳极氧化铝(AAO)模板内制备了镍纳米线,然后在800℃下氧化8h得到NiO纳米线。利用X射线衍射(XRD)、原子力显微镜(AFM)和扫描电子显微镜(SEM)对NiO纳米线的组成、结构和形貌进行了表征,并测试了NiO/AAO阵列体系的光电压。测试结果表明:NiO纳米线为面心立方结构,平均晶粒尺寸为50nm,纳米线直径约90nm,与模板孔径相当;长度约为25μm,并受镍纳米线沉积时间的影响;在紫外灯(365nm)照射下,40V比60VNiO/AAO阵列体系的光电压大。     

铜金属纳米线的制备及其图案化

采用电化学沉积法在孔径为200nm的阳极氧化铝膜AAO模板中成功制备了Cu金属纳米线阵列、结合紫外线光刻法组装了图案化铜纳米线阵列.电化学沉积法可通过控制沉积时间来获得具有不同长径比的铜纳米线阵列;图案化的纳米线排列规整,高度有序;且纳米线组成的形状与掩膜相同.     

一维铂纳米线阵列的模板电沉积及其表征

将一种复合无机介孔膜作为新型的模板应用于一维纳米线阵列的模板合成研究中,通过采用模板恒电位沉积的方法制备出一维铂纳米线阵列,并利用扫描电镜,透射电镜,X射线衍射,能量分布谱,选区电子衍射对该铂纳米线阵列进行了表征。结果表明:通过模板恒电位沉积的方法可以将金属铂组装在复合无机介孔膜内的二氧化硅介孔管中,除去模板后,进而得到长度为10μm的一维多晶铂纳米线(半径为3～4nm)阵列。     

Fe21Ni79合金纳米线阵列的制备与磁性

用交流电化学沉积方法,在多孔铝阳极氧化膜的柱形孔内制备直径约60 nm,长度约为9.7 μm的Fe₂₁Ni₇₉合金纳米线.采用扫描电镜、透射电镜、X射线衍射仪和振动样品磁强计对纳米线的形貌 、结构和磁学性质进行了测试.结果表明,Fe₂₁Ni₇₉纳米线排列有序,长径比可控,合金呈fcc结构.当将其在外磁场下进行垂直磁化时,磁滞回线出现较高的矩形比0.86,矫顽力达1203Oe.且随着退火温度升高,矫顽力迅速增大,500℃时达到最大值1315Oe,之后又随退火温度的升高而下降.矩形比也呈现类似的变化规律.     

Tunable Magnetic Properties of Heterogeneous Nanobrush: From Nanowire to Nanofilm

With a bottom-up assemble technology, heterogeneous magnetic nanobrushes, consisting of Co nanowire arrays and ferromagnetic Fe₇₀Co₃₀ nanofilm, have been fabricated using an anodic aluminum oxide template method combining with sputtering technology. Magnetic measurement suggests that the magnetic anisotropy of nanobrush depends on the thickness of Fe₇₀Co₃₀ layer, and its total anisotropy originates from the competition between the shape anisotropy of nanowire arrays and nanofilm. Micromagnetic simulation result indicates that the switching field of nanobrush is 1900 Oe, while that of nanowire array is 2700 Oe. These suggest that the nanobrush film can promote the magnetization reversal processes of nanowire arrays in nanobrush.     

Isotropic magnetization response of electrodeposited nanocrystalline Ni–W alloy nanowire arrays

Isotropic magnetization response was demonstrated in electrodeposited nanocrystalline Ni–15 % W alloy nanowire arrays, which can be applied to nanoscale magnetic field sensors. The Ni–W alloy nanowire arrays were electrochemically synthesized on a nanochannel template electrode from an aqueous electrolytic solution. X-ray and electron diffraction patterns revealed that Ni–15 % W alloy deposits were composed of ultrafine crystal grains with a supersaturated solid solution phase. The magnetization of the Ni–15 % W alloy thin films reached saturation at around 2.5 kOe in a perpendicular direction to the film plane, whereas the pure Ni thin films hardly magnetized in the perpendicular direction. On the contrary, Ni–15 % W alloy nanowire arrays were easily magnetized, and reach saturation at around 1.0 kOe, even in a perpendicular direction to the array film plane that corresponds to the long-axis direction of the alloy nanowires.     

用多孔氧化铝膜为模板制备Fe磁性纳米线

铝在0．3mol／L草酸或硫酸介质中经过阳极氧化,得到不同孔径的多孔氧化铝模板,在此模板中电解沉积的Fe纳米线排布规则、有序,长径比约为150。根据测量的磁滞回线,可以看到制备的铁纳米线具有较大的磁各向异性,其垂直方向具有较高的矫顽力。     

Effects of anodization and electrodeposition conditions on the growth of copper and cobalt nanostructures in aluminum oxide films

Anodic aluminum oxide (AAO) films were prepared by alternative current (ac) oxidation in sulfuric acid and phosphoric acid solution. The porous structure of the AAO templates was probed by ac electrodeposition of copper. AAO templates grown using an applied square waveform signal in cold sulfuric acid solution exhibit a greater pore density and a more homogeneous barrier layer. UV–vis–NIR reflectance spectra of the Cu/AAO assemblies exhibit a plasmon absorption peak centered at 580 nm, consistent with the formation of Cu nanostructures slightly larger than 10 nm in diameter. Spectroscopic data also indicate that there is little or no oxide layer surrounding the Cu nanostructures grown by ac electrodeposition. The effect of pH of the cobalt plating solution on the magnetic properties of the Co/AAO assemblies was also investigated. Co nanowire arrays electrodeposited at pH 5.5 in H₂SO₄-grown AAO templates exhibit a fair coercivity of 1325 Oe, a magnetization squarness of about 72%, and a significant effective anisotropy. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

多孔阳极氧化铝模板组装Fe纳米线及其表征

Fe nanowire arrays are prepared by electrodeposition in porous anodic aluminum oxide template from a composite electrolyte solution. These nanowires have an uniform diameter of approximate 25 nm and a length in excess of 2.5μm.The micrographs and crystal structures of Fe nanowlres are studied by transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction(XRD). It is found that each nanowire is essentially a single crystal and has a different orientation in each array. Hysteresis loops of Fe nanowire array show that its easy magnetization direction is perpendicular to the sample plane.     

Electrodeposition of mesoporous manganese dioxide nanowires arrays from a novel conjunct template method

We report here for the first time on the synthesis of mesoporous MnO₂ nanowire array on conductive Ti/Si substrate. The morphology of the material is significantly controlled by the conjunct template of anodic aluminum oxide (AAO) and the hexagonal phase of a lyotropic liquid crystalline. Low-angle X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) studies show that the nanowires have a mesoporous structure consisting of cylindrical pores. Such a promising synthesis procedure may be a versatile approach that can be extended to the fabrication of other mesoporous metal/metal oxide, semiconductor, and polymer nanowire arrays.     

Ordered CoFe2O4 nanowire arrays with preferred crystal orientation and magnetic anisotropy

CoFe₂O₄ nanowire arrays were fabricated by electrodeposition of Fe²⁺ and Co²⁺ into anodic aluminum oxide (AAO) templates and further oxidization. The phase structure of the nanowires is cubic spinel-type, and the XRD result exhibits perfect preferred crystallite orientation along the nanowire axes. Compared with CoFe₂O₄ nanowire arrays synthesized by other methods, the magnetic hysteresis loops demonstrate that the arrays of nanowires exhibit uniaxial magnetic anisotropy with easy magnetization direction along the nanowire axes owing to the large shape anisotropy. This approach provides a facile technology to fabricate oxide nanowires with uniaxial magnetic anisotropy.     

Growth of mechanically fixed and isolated vertically aligned carbon nanotubes and nanofibers by DC plasma-enhanced hot filament chemical vapor deposition

Vertically aligned, mechanically isolated, multiwalled carbon nanotubes (MWCNTs) and nanofibers (MWCNFs) were grown using an array of catalyst nickel nanowires embedded in an anodic aluminum oxide (AAO) nanopore template using DC plasma-enhanced hot filament chemical vapor deposition (HFCVD). The nickel nanowire array, prepared by electrodeposition of nickel into the pores of a commercially available AAO membrane, acts as a template for CNT and CNF growth. It also provides both a mechanical “fixed support” boundary condition and enforces sufficient spatial separation of the CNT/CNFs from each other to enable reliable and well-controlled mechanical testing of individual vertically aligned CNT/CNFs. In contrast with other AAO-templated growth methods, no post-growth etching of the AAO is required, since the CNTs/CNFs grow out of the pores and remain vertically aligned. A mixture of hydrogen and methane was used for the growth, with hydrogen acting as a dilution and source gas for the DC plasma, and methane as the carbon source. A negative bias was applied to the sample mount to generate the DC plasma. The filaments provided the necessary heat for dissociation of molecular species, and also heat the sample itself significantly. Both of these effects assist the CNT/CNF growth. Minimal heating came from the low-power plasma. However, the associated DC field was essential for the vertical alignment of the CNTs and CNFs. Scanning electron, transmission electron, and atomic force microscopy confirm that the CNT/CNFs are composed of graphitic layers, and form a vertically aligned, relatively uniform, and dense array across the AAO template. A significant number of the structures grown are indeed high quality nanotubes, as opposed to more defective nanofibers that are often predominant in other growth methods. This method has the advantage of being scalable and consuming less power than other techniques that grow vertically aligned CNTs/CNFs.