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1.
Wafer scale (cm(2)) arrays and networks of nanochannels were created in polydimethylsiloxane (PDMS) from a surface pattern of electrodeposited gold nanowires in a master-replica process and characterized with scanning electron microscopy (SEM), atomic force microscopy (AFM), and fluorescence imaging measurements. Patterns of gold nanowires with cross-sectional dimensions as small as 50 nm in height and 100 nm in width were prepared on silica substrates using the process of lithographically patterned nanowire electrodeposition (LPNE). These nanowire patterns were then employed as masters for the fabrication of inverse replica nanochannels in a special formulation of PDMS. SEM and AFM measurements verified a linear correlation between the widths and heights of the nanowires and nanochannels over a range of 50 to 500 nm. The PDMS replica was then oxygen plasma-bonded to a glass substrate in order to create a linear array of nanofluidic channels (up to 1 mm in length) filled with solutions of either fluorescent dye or 20 nm diameter fluorescent polymer nanoparticles. Nanochannel continuity and a 99% fill success rate was determined from the fluorescence imaging measurements, and the electrophoretic injection of both dye and nanoparticles in the nanochannel arrays was also demonstrated. Employing a double LPNE fabrication method, this master-replica process was also used to create a large two-dimensional network of crossed nanofluidic channels. 相似文献
2.
Bismuth telluride (Bi2Te3) nanowires were deposited into porous alumina templates with 35 nm diameter pores by a pulsed-potential electrodeposition method. For growth at temperatures between 1 and 4 degrees C, the nanowires filled 93% of the pores of the template, and the growth fronts were uniform with nanowire lengths of approximately 62-68 microm. There are over ten billion nanowires per square centimeter with aspect ratios approaching 2000:1. Samples were characterized by scanning and transmission electron microscopy, X-ray diffraction, and electron microprobe analysis. The crystalline nanowire arrays are highly oriented in the [110] direction, which is optimal for thermoelectric applications. 相似文献
3.
Nanowire fabrication methods can be classified either as 'top down', involving photo- or electron-beam lithography, or 'bottom up', involving the synthesis of nanowires from molecular precursors. Lithographically patterned nanowire electrodeposition (LPNE) combines attributes of photolithography with the versatility of bottom-up electrochemical synthesis. Photolithography defines the position of a sacrificial nickel nanoband electrode, which is recessed into a horizontal trench. This trench acts as a 'nanoform' to define the thickness of an incipient nanowire during its electrodeposition. The electrodeposition duration determines the width of the nanowire. Removal of the photoresist and nickel exposes a polycrystalline nanowire--composed of gold, platinum or palladium--characterized by thickness and width that can be independently controlled down to 18 and 40 nm, respectively. Metal nanowires prepared by LPNE may have applications in chemical sensing and optical signal processing, and as interconnects in nanoelectronic devices. 相似文献
4.
The Seebeck coefficient, S, and the electrical conductivity, σ, of electrodeposited poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires and thin films are reported. PEDOT nanowires were prepared by electropolymerizing 3,4-ethylenedioxythiophene (EDOT) in aqueous LiClO(4) within a template prepared using the lithographically patterned nanowire electrodeposition (LPNE) process. These nanowires were 40-90 nm in thickness, 150-580 nm in width, and 200 μm in length. σ and S were measured from 190 K to 310 K by fabricating heaters and thermocouples on top of arrays of 750 PEDOT nanowires. Such PEDOT nanowire arrays consistently produced S values that were higher than those for PEDOT films: up to -122 μV/K (310 K) for nanowires and up to -57 μV/K (310 K) for films. The sample-to-sample variation in S for 14 samples of PEDOT nanowires and films, across a wide range of critical dimensions, is fully explained by variations in the carrier concentrations in accordance with the Mott equation. In spite of their higher |S| values, PEDOT nanowires also had higher σ than films, on average, because electron mobilities were greater in nanowires by a factor of 3. 相似文献
5.
Highly ordered porous anodic aluminum oxide (OPAA) on aluminum substrate with an ultrathin barrier layer was prepared by a two-step aluminum anodic oxidation plus a step-by-step voltage decrement process. Ag nanowire arrays have been successfully electrodeposited into the OPAA template through constant current technique. The morphology, composition and structure of the nanowire arrays were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that Ag nanowires possess smooth surface and high aspect ratio up to 330 with a diameter of 70-80 nm. Nearly 100% of the pores were filled by Ag nanowires, which have face center cubic structure and (111) preferential orientation. The branch of originally straight pores at the formation front was demonstrated and the branched pores favor the formation of several nucleation sites in each pore at the beginning of the electrodeposition. 相似文献
6.
《Materials Research Bulletin》2006,41(9):1729-1734
Ordered selenium nanowire arrays with diameters about 40 nm have been fabricated by electrodeposition using anodic porous alumina templates. As determined by X-ray diffraction, Raman spectra, electron diffraction and high-resolution transmission electron microscopy, selenium nanowires have uniform diameters, which are fully controllable. Single crystalline trigonal selenium nanowires have been obtained after postannealing at 180 °C. These nanowires are perfect with a c-axis growth orientation. The optical absorption spectra reveal two types of electron transition activity. 相似文献
7.
《Materials Letters》2005,59(8-9):981-984
Ordered monocrystalline cobalt nanowire array has successfully been synthesized in a porous alumina template by direct current electrodeposition. The as-obtained cobalt nanowires with diameters of 35 nm, 45 nm, 60 nm, and length of 18 μm have been observed by transmission electron microscopy (TEM). A highly preferential orientation of the cobalt nanowires has been obtained by X-ray diffraction (XRD), and the orientation grows better as the hole diameter gradually reduces. M–H hysteresis loops determined by a vibrating sample magnetometer (VSM) indicate that the nanowire arrays obtained possess an obvious magnetic anisotropy. 相似文献
8.
9.
The electrical resistance, R, of an array of 30 palladium nanowires is used to detect the concentration of dissolved hydrogen gas (H(2)) in transformer oil over the temperature range from 21 to 70 °C. The palladium nanowire array (PdNWA), consisting of Pd nanowires ~100 nm (width), ~20 nm (height), and 100 μm (length), was prepared using the lithographically patterned nanowire electrodeposition (LPNE) method. The R of the PdNWA increased by up to 8% upon exposure to dissolved H(2) at concentrations above 1.0 ppm and up to 2940 ppm at 21 °C. The measured limit-of-detection for dissolved H(2) was 1.0 ppm at 21 °C and 1.6 ppm at 70 °C. The increase in resistance induced by exposure to H(2) was linear with [H(2)](oil)(1/2) across this concentration range. A PdNWA sensor operating in flowing transformer oil has functioned continuously for 150 days. 相似文献
10.
Arrays of thermoelectric bismuth telluride (Bi(2)Te(3)) nanowires were grown into porous anodic alumina (PAA) membranes prepared by a two-step anodization. Bi(2)Te(3) nanowire arrays were deposited by galvanostatic, potentiostatic and pulsed electrodeposition from aqueous solution at room temperature. Depending on the electrodeposition method and as a consequence of different growth mechanisms, Bi(2)Te(3) nanowires exhibit different types of crystalline microstructure. Bi(2)Te(3) nanowire arrays, especially those grown by pulsed electrodeposition, have a highly oriented crystalline structure and were grown uniformly as compared to those grown by other electrodeposition techniques used. X-ray diffraction (XRD) analyses are indicative of the existence of a preferred growth orientation. High resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED) confirm the formation of a preferred orientation and highly crystalline structure of the grown nanowires. The nanowires were further analyzed by scanning electron microscopy (SEM). Energy dispersive x-ray spectrometry (EDX) indicates that the composition of Bi-Te nanowires can be controlled by the electrodeposition method and the relaxation time in the pulsed electrodeposition approach. The samples fabricated by pulsed electrodeposition were electrically characterized within the temperature range 240?K≤T≤470?K. Below T≈440?K, the nanowire arrays exhibited a semiconducting behavior. Depending on the relaxation time in the pulsed electrodeposition, the semiconductor energy gaps were estimated to be 210-290?meV. At higher temperatures, as a consequence of the enhanced carrier-phonon scattering, the measured electrical resistances increased slightly. The Seebeck coefficient was measured for every Bi(2)Te(3) sample at room temperature by a very simple method. All samples showed a positive value (12-33?μV?K(-1)), indicating a p-type semiconductor behavior. 相似文献
11.
Mojgan Najafi Parnaz Assari Amir Abbas Rafati Mandana Hamehvaisy 《Journal of Superconductivity and Novel Magnetism》2014,27(12):2821-2827
Highly ordered [Co 0.975Cr 0.025]0.99Cu 0.01 nanowire arrays were electrodeposited by conducting alternating current (AC) conditions from sulfate-based electrolyte into nanopores of anodic aluminum oxide (AAO) template with 37 nm pore diameter and the interpore distances of almost 50 nm. Fabricated nanowire arrays were characterized using scanning electron microscopy, alternating gradient force magnetometer, and X-ray diffraction. The results illustrated that varying frequency, wave form, and annealing procedure had influence on magnetic properties of as deposited nanowires. The nanowire arrays electrodeposited at different electrodeposition frequencies show remarkably different magnetic behaviors. Due to increasing of the electrodeposition frequency, the rate of ions for reduction was decreased. The nanowires prepared at various wave form illustrated insignificant impact on magnetic properties. X-ray diffraction patterns display that both as-deposited and annealed nanowire arrays expose the same structure. The raised value of coercivity has been determined in annealed nanowire arrays. Magnetization measurements show that the maximum value of coercivity for [Co 0.975]0.99Cu 0.01 nanowires is observed at high temperature. 相似文献
12.
Highly ordered hydroxyapatite (HA) nanowire arrays were synthesized using porous anodic aluminum oxide (AAO) template from sol-gel solution containing P2O5 and Ca(NO3)2. Theresults of transmission electron microscopy (TEM) and scanning electron microscopy(SEM) revealed that the obtained HA nanowires had a uniform length and diameter andformed highly ordered arrays, which were determined by the pore diameter and thethickness of the applied AAO template. The results of X-ray diffraction (XRD) and X-rayphotoelectron spectroscopy (XPS) demonstrated that the major component was HA. Theselected-area electron diffraction (SAED) results indicated that HA was a polycrystallinestructure. This novel method of preparing highly ordered HA nanowires with a large areamight be important for many applications in biomaterials. 相似文献
13.
Kai Huang 《Materials Research Bulletin》2008,43(4):919-925
Tungsten oxide nanowire arrays have been grown on indium tin oxide coated glass substrate using tungsten trioxide powders as source by thermal evaporation approach without any catalysts. When the O2/Ar flow rate ratio was 1/100, large-scale, high-density and uniformly distributed tungsten oxide nanowire arrays were obtained. The morphology and structure properties of the tungsten oxide nanowires were characterized by scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. The influences of the oxygen concentration on the growth, density, shape and structure of the nanowires were investigated. The possible growth mechanism which governs the various types of nanowire arrays as the O2/Ar flow rate ratios changed is also discussed. Field emission properties of tungsten oxide nanowire arrays were studied at a poor vacuum condition. The remarkable performance reveals that the tungsten oxide nanowire arrays can be served as a good candidate for commercial application as electron emitters. 相似文献
14.
X.S Peng G.W MengJ Zhang X.F WangL.X Zhao Y.W WangL.D Zhang 《Materials Research Bulletin》2002,37(7):1369-1375
We have successfully fabricated ordered crystalline Ag2S nanowire arrays by direct current electrodeposition into the nanochannels of porous anodic aluminum oxide templates from a dimethylsulfoxide solution containing AgNO3 and elemental S. X-ray diffraction and the selected area electron diffraction investigations demonstrate that the Ag2S nanowires are a uniform actanthite structure. Electromicroscopy results show that the nanowires are quite ordered with diameters of about 40 nm and lengths up to 5 μm. X-ray energy dispersion analysis indicates that the atomic composition of Ag and S is very close to a 2:1 stoichiometry. Furthermore, a possible mechanism for the formation of the Ag2S nanowires is proposed. 相似文献
15.
Fe3Co7 alloy nanowire arrays have been fabricated by direct current electrodeposition of Fe2+ and Co2+ into anodic aluminum oxide (AAO) templates. The phase structure and magnetic properties of the nanowires were studied by
transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and vibrating sample
magnetometer (VSM). Magnetic measurements show that the coercivity and remanence of the as-deposited Fe3Co7 Alloy nanowires increase dramatically after heat-treatment at 773 K for 2 h, and the nanowire arrays exhibit uniaxial magnetic
anisotropy with easy magnetization direction along the nanowire axes owing to the large shape anisotropy. The great difference
between practical coercivity and ideal coercivity was also discussed in detail. 相似文献
16.
夏金德 《材料科学与工程学报》2006,24(2):289-291
采用真空灌注结合溶胶-凝胶和氧化铝模板法,在多孔氧化铝模板中制备了平均直径为50 nm的NiFe2O4纳米线阵列.X射线衍射结果显示所制备的纳米线是纯相的NiFe2O4纳米线,透射电镜和电子衍射的结果显示已制备的纳米线是多晶的且表面光滑,场发射扫描电镜图片显示纳米线是大面积且平行有序的、纳米线的长度和所用的氧化铝模板的厚度相当.磁测量的结果显示此纳米线阵列有形状各向异性,同块状材料相比矫顽力有所增强.对纳米线的生长机理做了简单的讨论. 相似文献
17.
Yong Ren Jianbo Wang Qingfang Liu Yingying Dai Bin Zhang Longgang Yan 《Journal of Materials Science》2011,46(23):7545-7550
To tailor coercivity and magnetic anisotropy, we have fabricated Co nanowire arrays in the pores of anodic aluminum oxide
templates by electrodeposition. Microstructure measurements performed by X-ray diffraction show that Co nanowire arrays are
hexagonal close-packed (HCP) structures with different crystalline textures. A wide range in change of coercivity from 925
to 3310 Oe at 300 K, with a maximum of up to 4050 Oe at 5 K, can be found for nanowire arrays with a diameter of 20 nm. This
may be the highest value and the widest range of coercivity reported for Co nanowires prepared by electrodeposition method.
This finding could be attributed to the adjustment of the microstructure of the cobalt nanowire arrays prepared in different
experimental conditions. We have also investigated the relationship between the crystalline textures and the magnetic properties
of Co nanowire arrays using micromagnetic simulation combined with microstructure measurements. The preferred orientation
of nanowire arrays, such as (1000) or (0002), is a key factor in determining coercivity. This wide tailoring of coercivity
makes possible more promising applications of Co nanowire arrays with fixed diameter and length. 相似文献
18.
Crystalline PbS nanowire arrays have been successfully fabricated by AC applied DC electrochemical deposition from aqueous solutions of dimethylsulfoxide DMSO solution containing lead chloride and elemental sulfur into sulfuric anodic alumina membranes (AAM). These nanowires have uniform diameters of approximately 30 nm, and their lengths are up to tens of micrometers. Scanning electron microscopy indicates that the ordered PbS nanowire arrays are completely embedded. The results of X-ray diffraction show that the as-synthesized nanowires are crystalline with highly preferential orientation. Energy dispersive spectrometer analysis shows that the composition ratio is very close to 1:1. Finally PL and UV–VIS illustrate the quantum confinement effects of PbS nanowire arrays. 相似文献
19.
Yu-Min Shen Yueh-Ting Shih Sheng-Chang Wang Pramoda K. Nayak Jow-Lay Huang 《Thin solid films》2010,519(5):1687-1692
Cu nanowire arrays were synthesized via a porous alumina membrane (PAM) template with a high aspect ratio, uniform pore size (120–140 nm), and ordered pore arrangement. The Cu2O nanowire arrays were prepared from the oxidization of Cu metal nanowire arrays. The electrochemical deposition potential of Cu metal nanowires (?180 mV vs. SCE) was determined from X-ray diffraction (XRD) patterns. The microstructure and chemical composition of Cu nanowire arrays were characterized using field emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), and X-ray diffraction (XRD). Results indicate that the Cu/Cu2O nanowire arrays assembled into the nanochannel of the porous alumina template with diameters of 120–140 nm. The valence of copper was controlled by the porous alumina template during the annealing process. Copper nanowires transformed to the Cu2O phase with the space limitation of the PAM template. Single-crystal Cu2O nanowire arrays were also obtained under the template embedded. 相似文献