直流电沉积法制备镍纳米线（阵列）及其磁性能研究

采用直流电化学沉积方法,在经过阶梯降压处理的多孔阳极氧化铝模板纳米级孔洞中,制备出直径约30nm,长度超过10μm的金属镍纳米线(阵列).通过场发射扫描电子显微镜,透射电子显微镜,X射线衍射仪,振动样品磁强计对所制备的样品进行形貌、结构及相关性能的表征和测试.结果表明所制备的镍纳米线排列规整,形态均匀,呈fcc结构,且沿[111]方向择优生长,易磁化方向沿纳米线长轴方向.     

Fabrication and optical property of single-crystalline InSb nanowire arrays

Semiconductor InSb nanowire arrays have been synthesized by the pulsed electrochemical deposition from citric acid aqueous solution into anodic alumina membranes. It was found that the InSb nanowires are of zinc-blende structure, and high filling rate and single-crystalline InSb nanowire array with right stoichiometric composition can be fabricated by proper controlling of the concentration of In and Sb ions and the PH value in the electrolyte and the pulse voltage, and the nanowires have [100] orientation with structure defects such as twins. The optical band gap has a strong blue shift with decreasing the diameter of the nanowire due to the quantum confinement effect.     

Fabrication of metallic nanowire arrays by electrodeposition into nanoporous alumina membranes: effect of barrier layer

Deposition into nanoporous alumina membranes is widely used for nanowire fabrication. Herein using AC electrodeposition ternary Fe–Co–Ni nanowires are fabricated within the nanoscale-pores of alumina membranes. Using an electrodeposition frequency of 1,000 Hz, 15 V_rms, consistently and repeatably yield nanowire arrays over membranes several cm² in extent. Electrochemical Impedance Spectroscopy (EIS) is used to explain the effects of AC electrodeposition frequency. The impedance of the residual alumina barrier layer, separating the underlying aluminum metal and the nanoporous membrane, decreases drastically with electrodeposition frequency facilitating uniform pore-filling of samples several cm² in area. Anodic polarization studies on thin films having alloy compositions identical to the nanowires display excellent corrosion resistance properties.     

Fabrication of superhydrophobic surfaces by a Pt nanowire array on Ti/Si substrates

Superhydrophobic surfaces were prepared on Ti/Si substrates via the fabrication of a platinum (Pt) nanowire array. The Pt nanowire array was obtained by dc electrodeposition of Pt into the pores of an anodic aluminium oxide (AAO) template on the substrate followed by the removal of the template. Transmission electron microscopy (TEM) examination demonstrated that all the nanowires have uniform diameter of about 30?nm. Field emission scanning electron microscopy (FE-SEM) showed that the structures at both the micrometre scale and nanometre scale bestowed the prerequisite roughness on the surfaces. The chemical surface modification made the Pt nanowire array superhydrophobic. The surface modified Pt nanowire array exhibited superhydrophobicity even in corrosive solutions over a wide pH range, such as acidic or basic solutions. The results demonstrated that the Pt nanowire array will have good potential applications in the preparation of superhydrophobic surfaces.     

基于TNT敏感聚合物的纳米阵列结构的制备与性质

利用多孔氧化铝模板法制备了两种1,3,5-trinitrotoluene(TNT)敏感的荧光共轭聚合物Tri-phenylamine-CO-para-biphenyene vinylene(TPA-PBPV)和Triphenylamine-co-para-phenyl-ene vinylene(TPA-PPV)的纳米线阵列结构.纳米线的直径在80～100 nm之间,高度在150-200nm之间.和固体薄膜相比,TPA-PBPV和TPA-PPV荧光光谱都发生了蓝移,TPA-PBPV的发射峰从485变为455 nm,PPV的峰从495 nm变为475 nm.蓝移的发光表明聚合物纳米线阵列可以抑制低能量陷阱,有望提高材料的传感性能.     

Structural and magnetic properties of Co and Co71Ni29 nanowire arrays prepared by template electrodeposition

A comparative study on the structural and magnetic properties of Co and Co₇₁Ni₂₉ nanowire arrays prepared by AC electrodeposition in alumina templates has been presented. The Co and Co₇₁Ni₂₉ nanowires observed by SEM and TEM have a 45 nm diameter and exhibit high aspect ratio. Also, the nanowires of both Co and Co₇₁Ni₂₉, determined by XRD, have an identical crystallographic structure. The Co₇₁Ni₂₉ nanowires exist in a cobalt solid solution. Both the as-obtained Co and Co₇₁Ni₂₉ nanowire arrays measured by VSM show obvious magnetic anisotropy, dominated by shape anisotropy. Compared to the Co nanowire arrays, Co₇₁Ni₂₉ nanowire array shows an enhanced coercivity Hc (⊥) and approximate square ratio Mr/Ms(⊥).     

智能剥离技术制备单晶 SOG材料的研究

结合中等剂量的氢离子注入和阳极键合(Anodic bonding)，利用智能剥离技术(Smart—cut)成功转移了一层单晶硅到玻璃衬底上。采用剖面透射电镜、高分辨透射电镜、扫描电镜和拉曼光谱等对SOG材料进行了研究，结果表明此技术制备的SOG材料具有界面陡峭、平整，顶层硅单晶质量完好等优点。     

Fabrication and field emission property of a Si nanotip array

Using a Si-based porous anodic alumina membrane as a mask, we demonstrate a way to pattern Si surface. After removing the SiO(2) nanoislands formed during anodization of the Al/Si interface, we obtain a Si nanotip array on the surface of a Si wafer. This array shows an excellent field emission property with a low turn-on field of 8.5?V?μm(-1). The Fowler-Nordheim plot obtained is linearly dependent, indicating that the emission current arises from the quantum tunnelling effect. The Si nanotip array can be expected to have important applications in nanoelectronic devices.     

Synthesis of PbTe nanowire arrays using lithographically patterned nanowire electrodeposition

We describe the preparation by electrodeposition of arrays of lead telluride (PbTe) nanowires using the lithographically patterned nanowire electrodeposition (LPNE) method. PbTe nanowires had a rectangular cross-section with adjustable width and height ranging between 60-400 nm (w) and 20-100 nm (h). The characterization of these nanowire arrays using X-ray diffraction, transmission electron microscopy and electron diffraction, scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy (XPS) is reported. PbTe nanowires were electrodeposited using a cyclic electrodeposition-stripping technique that produced polycrystalline, stoichiometric, face-centered cubic PbTe with a mean grain diameter of 10-20 nm. These nanowires were more than 1 mm in length and two additional processing steps permitted their suspension across 25 microm air gaps microfabricated on these surfaces. The LPNE synthesis of lithographically patterned PbTe nanowires was carried out in unfiltered laboratory air. Nanowires with lengths of 70-100 microm showed an electrical resistivity comparable to bulk PbTe. XPS reveals that exposure of PbTe nanowires to air causes the formation on the nanowire surface of approximately one monolayer of a mixed lead oxide and tellurium oxide within a few minutes.     

Fabrication of amorphous Co and Co-P nanometer array with different shapes in alumina template by AC electrodeposition

Using the porous alumina film as a template, the arrays of Co and Co-P with different shapes have been fabricated by AC electrodeposition. The as-obtained samples have been characterized by AFM, TEM and EDS. The results indicate that a small amount of non-metallic phosphor added in the electrolyte has a notable influence on the morphologies of electrodeposited nanostructural materials. An array of pure cobalt nanowires can be obtained, however, a mixed array of Co-P nanowires and nanotubes doped 2.0 at.% phosphor can be produced when the electrolytic solution contains 5.0 g/L sodium hypophosphite (NaH₂PO₂–H₂O) during the process of electrodeposition. Furthermore, only a Co-P nanoparticle array can be synthesized when the sodium hypophosphite (NaH₂PO₂–H₂O,) was raised to 10.0 g/L in the electrolytic solution. Also, the Co and Co-P nanowires, nanotubes and nanoparticles obtained display identical amorphous structure.     

CoFe2O4纳米线阵列的制备与磁性

在氧化铝模板的纳米孔洞中,用电化学的方法沉积钴铁合金纳米线,经过550℃、30h氧化处理,成功制备出钴铁氧体纳米线阵列.分别用透射电子显微镜(TEM)、X射线衍射仪(XRD)和振动样品磁场计(VSM)对样品的形貌、晶体结构和磁学性质进行了表征测试.TEM观察结果显示纳米线粗细均匀,直径约为70nm.XRD显示纳米线的物相结构为CoFe2O4;VSM测试结果表明,CoFe2O4纳米线阵列的磁滞回线矫顽力为1.190×105A/m,比氧化处理前的钴铁合金纳米线阵列有显著提高.     

Fabrication, characterization and property of microfibrous polyoxometalates containing cobalt or nickel

In this paper, fibrous membranes of poly(vinyl alcohol)/α-2-K₈P₂W₁₇MO₆₁ (M = Co, Ni) were prepared by electrospinning technique. Calcining the fibrous membranes at 340 °C for 6 h, fibrous membranes of pure α-2-K₈P₂W₁₇CoO₆₁ and α-2-K₈P₂W₁₇NiO₆₁ were obtained, respectively. Fourier transformation infrared spectroscopy and X-ray diffraction showed that Dawson-Wells structure of the polyoxometalates was still remained in the fibrous membranes. Scanning electron microscopy images and diameter distribution curves of the fibrous membranes indicated that the average diameter of α-2-K₈P₂W₁₇CoO₆₁ fibers was about 145 nm, and α-2-K₈P₂W₁₇NiO₆₁ about 168 nm. The magnetic property of the fibrous membranes was investigated.     

Fabrication of CoZn alloy nanowire arrays: Significant improvement in magnetic properties by annealing process

Highly ordered arrays of Co_1−xZn_x (0 ≤ x ≤ 0.74) nanowires (NWs) with diameters of ∼35 nm and high length-to-diameter ratios (up to 150) were fabricated by co-electrodeposition of Co and Zn into pores of anodized aluminum oxide (AAO) templates. The Co and Zn contents of the NWs were adjusted by varying the ratio of Zn and Co ion concentrations in the electrolyte. The effect of the Zn content, electrodeposition conditions (frequency and pH) and annealing on the structural and magnetic properties (e.g., coercivity (Hc) and squareness (Sq)) of NW arrays were investigated using X-ray diffraction (XRD), scanning electron microscopy, electron diffraction, and alternating gradient force magnetometer (AGFM). XRD patterns reveal that an increase in the concentration of Zn ions of the electrolyte forces the hcp crystal structure of Co NWs to change into an amorphous phase, resulting in a significant reduction in Hc. It was found that the magnetic properties of NWs can be significantly improved by appropriate annealing process. The highest values for Hc (2050 Oe) and Sq (0.98) were obtained for NWs electrodeposited using 0.95/0.05 Co:Zn concentrations at 200 Hz and annealed at 575 °C. While the pH of electrolyte is found to have no significant effect on the structural and magnetic properties of the NW arrays, the electrodeposition frequency has considerable effects on the magnetic properties of the NW arrays. The changes in magnetic property of NWs are rooted in a competition between shape anisotropy and magnetocrystalline anisotropy in NWs.     

Improved microstructure and magnetic properties of iron-cobalt nanowire via an ac electrodeposition with a multistep voltage

Highly ordered porous alumina templates prepared by a two-step anodization are widely utilized as the matrix to assemble nanowires. Usually, an ac electrodeposition with a constant voltage is employed to deposit the metal nanowires on the porous alumina template due to its simple electrodeposition process. However, the nanowires deposited under a constant voltage include many defects in the microstructure, e.g. the hole to weaken its physical properties. Recently, we used an ac electrodeposition with a multistep voltage to deposit a cobalt nanowire with less microstructure defects to enhance its magnetic properties. In this letter, we further investigate the microstructure and magnetic properties of the iron-cobalt nanowire via an ac electrodeposition with a multistep voltage on the porous alumina template. Such a FeCo nanowire has the more uniform crystalline microstructure than that of deposited under a constant voltage and thus the magnetic properties are improved. Our results indicate that an ac electrodeposition with a multistep voltage is an effective way to fabricate the nanowires on the porous alumina template.     

Fabrication and electrical properties of a Cu-tetracyanoquinodimethane nanowire array in a porous anodic alumina template

A nanowire array of metal-organic complex copper-tetracyanoquinodimethane (CuTCNQ) was obtained by depositing a layer of copper in the bottom of anodic alumina template channels during a vapor-induced reaction method. SEM observation showed that the channel diameters of anodic alumina membranes prepared under 40?V and 200?V are about 60?nm and 200?nm, respectively, and CuTCNQ nanowire arrays were synthesized in these channels. Nanodevice prototypes with electrical switching characteristics based on a CuTCNQ nanowire array were fabricated, whose reproducible electrical switching and memory effects were observed. The on-off ratio for switching reaches 10(4). The potential applications in information storage devices are also discussed.     

Fabrication of a porous polyimide membrane using a silicon nanowire array as a template

We demonstrate that a porous polyimide membrane can be fabricated by curing liquid polyimide on a vertically oriented silicon nanowire array and selectively etching away the nanowire-array-template using xenon difluoride (XeF₂). Pore size and density using the described technique are controllable. The former is dependent on nanowire diameter and the duration of etching, whereas pore density is determined by silicon nanowire density. We believe that the described porous membrane fabrication method can be applied to various polymer and nanowire systems.     

ZnO纳米线阵列修饰对材料表面浸润性调控

采用溶胶-凝胶法制备了ZnO薄膜,利用溶剂热沉积法获得大面积均匀ZnO纳米线阵列。通过对水在ZnO材料表面的浸润性研究,发现薄膜材料表面的粗糙度对ZnO膜亲水性有增强作用,而周期性ZnO阵列微结构表面可以实现其疏水性质增强效果。同时从理论上分析了这两种现象的物理机制,讨论了空气填隙对ZnO纳米线阵列表面的浸润性质的敏感性。制备出ZnO纳米线阵列的表观接触角约为103°,具有较强的疏水性质,可为进一步的ZnO光流控研究提供实验基础。     

Fabrication of transparent conducting amorphous Zn-Sn-In-O thin films by direct current magnetron sputtering

Amorphous ZnO-SnO₂-In₂O₃ films were grown by direct current magnetron sputtering from vacuum hot pressed ceramic oxide targets of Zn:In:Sn cation ratios 1:2:1 and 1:2:1.5 onto glass substrates. X-ray diffraction analysis showed that the microstructure remained amorphous during annealing at 200 °C for up to 5 hours. By monitoring the electrical resistivity, oxygen content and substrate temperature were optimized during deposition. The optimal films were characterized by Hall Effect, work function and optical spectroscopy measurements. Films of 1:2:1 composition showed the lowest resistivity (7.6 × 10^− 4 Ω-cm), when deposited onto substrates preheated to 300 °C. Transmissivity of all films exceeded 80% in the visible spectral region. The energy gap was 3.52-3.74 eV, and the work function ranged 5.08-5.22 eV, suitable for cathode applications in organic light emitting diodes. Overall, the film characteristics were comparable or superior to those of amorphous tin-doped indium oxide and zinc-doped indium oxide films and may serve as viable, lower-cost alternatives.     

Fabrication of iron oxide nanoparticles: magnetic and electrochemical sensing property

In this paper, we report a simple synthesis of Fe₂O₃ nanoparticles using hydrothermal method. The formation of the sample was confirmed by X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transformed infrared spectroscopy, Raman spectroscopy and UV–Visible absorption spectroscopy. The average crystallite size of the synthesized Fe₂O₃ nanoparticles was estimated to be 61 nm and the particles were of good crystalline nature. Field emission-scanning electron microscopy study of the sample revealed that the Fe₂O₃ powder has rod-like morphology which is composed of nanoparticles. The vibrating sample magnetometer measurement shows that the nanoparticles possess ferromagnetic property. The synthesized Fe₂O₃ nanoparticles were used to modify glassy carbon electrode (Fe₂O₃/GCE) and the modified electrode was used to detect pyrocatechol (PC) in a pH 7.4 phosphate buffer solutions by cyclic voltammetry and chronoamperometry. At the Fe₂O₃/GCE, PC is oxidized at less positive potential with larger current response than the bare GCE. The proposed sensor exhibits great potential in the field of electrochemical sensing of PC.     

Fabrication of multi-emitter array of CNT for enhancement of current density

We studied and compared field emission properties of two kinds of emitters of randomly oriented multi-wall carbon nanotubes (MWNTs), viz. continuous film emitter (CFE) and multi-emitter array (MEA). The CFE has a continuous film of MWNTs while the MEA consists of many equidistant small circular emitters. Both types of emitters were prepared by dispersing MWNTs over a titanium (Ti) film (for CFEs) or Ti circular islands (for MEAs) deposited on tantalum (Ta) followed by rooting of MWNTs into the Ti film or the Ti islands at high temperature. Emission properties of both types of emitters were analyzed with changing their emission areas. In case of the CFEs, current density decreased with an increase in emission area whereas consistent current densities were achieved from MEAs with different emission areas. In other words, the total emission current was achieved in proportion to the emission area in the case of MEAs. Additionally a high current density of 22 A/cm² was achieved at an electric field of 8 V/μm from MEAs, which was far better than that obtained from CFEs. The high current density in MEAs was attributed to edge effect, in which higher emission current is achieved from the edge of film emitter. The results indicate that the field emission characteristics can be greatly improved if a cathode contains many small equidistant circular emitters instead of a continuous film. The outstanding stability of the CFE and the MEA has been demonstrated for 2100 and 1007 h, respectively.