双槽法电沉积Cu/Ni多层纳米线有序阵列

以多孔阳极氧化铝（AAO）为模板，采用双槽法电沉积工艺制得高度有序的Cu/Ni多层纳米线阵列。利用扫描电镜（SEM）和透射电镜（TEM）对Cu/Ni多层纳米线进行了表征，观察到纳米线表面平滑，多层结构清晰，各子层厚度均匀，直径约为 100 nm，与AAO模板孔径基本一致。由选区电子衍射（SAED）照片可知，多层纳米线中Cu层和Ni层均为单晶结构。振动样品磁强计（VSM）测试结果表明，Cu/Ni多层纳米线阵列具有明显的垂直磁各向异性，外加磁场垂直和平行于AAO模板表面时，磁滞回线的矩形比分别为 0.701 和 0.101 ，矫顽力分别为 589 Oe和 202 Oe。通过控制铝阳极氧化工艺及电沉积时间，可获得不同直径、不同子层厚度的Cu/Ni多层纳米线阵列。     

非晶Co-Pt合金纳米线有序阵列的制备及其磁学性质

通过直流电沉积方法，以多孔阳极氧化铝(AAO)为模板，在室温下成功制备出一维非晶态Co-Pt合金纳米线有序阵列. SEM和TEM分析表明：纳米线长度均约10 μm，直径35 nm；纳米线在阳极氧化铝模板孔内互相平行. XRD结果表明，制备的纳米线为非晶态结构，经过700 ℃退火处理后则转变为面心立方(FCC)多晶结构. 采用VSM(振动样品磁强计)对退火处理前后样品的矫顽力和剩磁比进行研究，结果表明：当外加磁场与纳米线平行时，非晶态Co-Pt合金纳米线的矫顽力高达1700 Oe，剩磁比为0.83，表现出明显的垂直磁各向异性；而退火处理则使其优秀的磁学性质消失. 退火前后不同的磁学性质源于其不同的微观结构. 非晶态的Co-Pt合金纳米线由于无磁晶各向异性竞争，进而使得由纳米线一维形态引起的形状各向异性起主导作用，使其显示了很好的垂直磁各向异性；而多晶样品由于磁晶各向异性与形状各向异性竞争，导致矫顽力和剩磁比迅速降低.     

直流电沉积Ni-Al2O3纳米阵列体系结构与性能

用直流电沉积的方法成功地将Ni金属填入了用二次腐蚀方法制备的氧化铝模板纳米级孔洞中，分别用电子显微镜、X射线衍射仪和振动样品磁强计对Ni阵列体系进行结构观察和磁性表征.结果表明，用二次腐蚀方法制得的多孔氧化铝模板的孔洞排布的有序性很高.被组装的Ni呈单晶结构并具有一定的择优取向； Ni-Al2O3阵列体系有明显的垂直磁各向异性，适用于垂直磁记录介质.     

Co/Cu多层纳米线阵列的制备与磁性能

利用双槽直流电沉积技术在阳极氧化铝(AAO)模板的纳米孔中获得调制波长为50 和200 nm 的Co/Cu多层纳米线, 多层纳米线的调制波长由电沉积时间控制. 运用扫描电子显微镜(SEM)和透射电子显微镜(TEM)表征纳米线的形貌, Co/Cu多层纳米线的长度约20 μm, 直径约80 nm; 用X射线衍射(XRD)研究多层线的结构; 用振动样品磁强计(VSM)测试纳米线阵列的磁性能; 利用可变磁场结合高灵敏度恒流装置研究巨磁电阻(GMR)特性. 结果表明, Co/Cu多层纳米线具有磁各向异性. 当磁场与纳米线平行和垂直时, 调制波长为50 nm的多层线的矫顽力分别为87500 和34200 A·m-1, 而调制波长为200 nm的多层线阵列的矫顽力分别为28600 和8000 A·m-1. 调制波长为50 nm的多层纳米线的磁电阻变化率高达-%, 而调制波长为200 nm的多层线未产生明显的GMR效应.     

单晶Ni纳米线阵列的制备与磁性能

采用恒电流沉积方法, 在多孔阳极氧化铝(AAO)模板中制备出了具有单晶结构的Ni纳米线阵列. 采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)技术对制备的Ni纳米线阵列的形貌及结构进行了表征. 利用振动样品磁强计(VSM)对单晶Ni纳米线阵列的磁性能进行了研究. 结果表明, 单晶镍纳米线阵列的易磁化方向为纳米线轴向, 并且与多晶纳米线相比显示出了更高的矫顽力. 直径为30 nm的纳米线具有较高的矫顽力(8.236×104 A/m)和较高的剩磁比(Mr＝0.94Ms).     

大长径比有序多孔阳极氧化铝模板的制备及用于镍纳米线阵列

报道一种恒电流二次氧化制备大长径比(>1000)阳极氧化铝(AAO)模板的方法,研究氧化时间和氧化电流密度分别对制备的AAO模板的表面形貌、孔径大小、厚度等的影响.结果表明,AAO模板的表面形貌及厚度n受m氧、厚化度电约流为密2度00及μ氧m、化长时径间比的为影10响0;-当13氧00化的电高流质密量度A为AO8模m板A·.c采m用-2电时化,氧学化沉1积8方h能法在制制备备出的孔A径A为O模15板0-的20孔0中成功制备了Ni纳米线阵列,分别用扫描电镜(SEM)、高分辨透射电镜(HRTEM)、X射线衍射(XRD)和X射线能量散射光谱(EDS)对其进行了表征;结果显示,制备的Ni纳米线排列整齐有序,每根Ni纳米线直径几乎相同,约150nm,长度约为180-200μm,长径比为1200-1300,与AAO模板的参数一致.研究了Ni纳米线阵列的长径比对其磁性能的影响,发现大长径比的Ni纳米线阵列具有明显的磁各向异性,而长径比约为200的Ni纳米线阵列未表现出明显的磁各向异性.本文结果表明,恒电流二次氧化方法能制备大长径比的AAO模板,并能用于制备大长径比的一维纳米材料阵列,可望在制备具有特殊光学、磁学等性能材料方面得到应用.     

CoNi-PVP复合催化剂的制备及对乙醇电催化氧化性能研究

采用还原-高分子稳定剂(PVP)络合保护的方法制备用于催化乙醇氧化的纳米复合材料CoNi-PVP.通过红外光谱(IR)、透射电镜(TEM)、扫描电镜能谱(SEM-EDS)等技术对纳米复合催化材料进行表征.结果显示,得到的产物为Co,Ni纳米线,直径3～5 nm,长度约100 nm.利用循环伏安和计时电流法测试了其在碱性介质中对乙醇电化学氧化的催化能力.CoNi-PVP-C电极中的Co、Ni金属含量为2%,PVP∶CoNi物质量比为5∶1时,对乙醇的电化学氧化有最佳催化活性.     

钴纳米线的模板制备与磁性

利用二次阳极氧化法制备了多孔阳极氧化铝模板. 用直流电化学沉积方法成功地在模板孔道内制备了钴纳米线. 采用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和振动样品磁强计(VSM)对样品的形貌、晶体结构和磁性进行了研究. 结果表明， 模板的孔径均匀, 孔道平直. 钴纳米线为多晶的六方密堆积结构. 钴纳米线具有明显的磁各向异性, 这主要起源于纳米线的形状各向异性.     

一种新的电化学方法制备CdS纳米线阵列

用一种新的电化学方法在多孔氧化铝模板中制备了CdS纳米线阵列体系,并用XRD、TEM对样品进行表征,结果显示CdS纳米线为立方相和六方相的多晶混合结构,对沉积机理进行了讨论.荧光光谱测量显示CdS纳米线阵列体系有三个强的紫外发光带和一个黄绿发光带.该文所使用的方法可以用来在氧化铝模板中制备其它材料的纳米线阵列体系.     

热处理对[NiFe/Cu/Co/Cu]_n多层纳米线磁性能的影响

采用双槽控电位法在阳极氧化铝(AAO)模板中制备了有序均一的[NiFe/Cu/Co/Cu]n多层纳米线阵列,并在不同温度下进行了热处理.利用X射线衍射(XRD)对热处理前后多层线的晶体结构进行了测试.考察了不同退火温度对多层线矫顽力、剩磁比、巨磁电阻(GMR)效应、磁灵敏度的影响.随热处理温度升高,多层纳米线中磁性微晶晶型取向越来越明显,晶体结构更均匀;多层纳米线的矫顽力和剩磁比先增大后减小.300°C下多层纳米线矫顽力达到最大值,GMR最大值可达59%,对应的磁电阻灵敏度(SV)为0.233%Oe-1.     

Annealing effects on the structure, photoluminescence, and magnetic properties of GaN/Mn3O4 core-shell nanowires

Nanowires consisting of GaN/Mn₃O₄ were prepared using a two-step approach that involved dipping the as-synthesized GaN nanowires into an aqueous manganese acetate solution. To examine the effects of annealing, GaN/Mn₃O₄ core-shell nanowires were heated thermally to 700 °C in N₂ ambient. Transmission electron microscopy showed that the continuous Mn₃O₄ shell layer had agglomerated to expose a bare GaN core surface after thermal annealing. The magnetic measurements showed that the ferromagnetic behavior of the GaN nanowires had been suppressed by coating with the Mn₃O₄ shell, without significant change by the subsequent thermal annealing. The GaN/Mn₃O₄ core-shell nanowires exhibited blue, green, and red photoluminescence (PL) emission. The red emission was enhanced by thermal annealing. This paper discusses the associated mechanism for the variations in PL and magnetic properties of GaN/Mn₃O₄ core-shell nanowires.     

Synthesis and thermal stability of ZnO nanowires

ZnO nanowires (NWs) were synthesized on Au-coated Si (100) substrates by vapor transport method. The effect of high temperature annealing on the structural and chemical composition as well as thermal stability was studied. The as-prepared ZnO NWs was nearly stoichiometric and identified as hexagonal ZnO phase. After annealing at 1,473 K, the atomic ratio of O/Zn, the intensity of the diffraction peaks, and the diameter of nanowires were increased. The ZnO NWs were fragmented into nanocrystals and the fragments coalesced with each other after annealing at 1,673 K. The thermal stability of ZnO NWs was studied by thermo-gravimetric (TG) analysis. A sharp increase in the TG curves was observed and can be attributed to the oxidation of some possibly presented Zn atoms. The activation energy of oxidation of Zn interstitial atoms was found to be 484.81 kJ mol^?1. A mass gain peak was observed after annealing at 1,473 K, but it was completely eliminated after annealing at 1,673 K.     

Synthesis of NiFe2O4 Nanowires with NiO Nanosheet as Precursor via a Topochemical Solid State Method

Large scale NiFe₂O₄ nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe₂O₄ annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Fe^- ions into NiFe₂O₄ nanowires. In the beginning stage of synthesizing process, the shape of NiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400℃ to 600℃. At last they transformed into nanoparticles from 700℃ to 1000℃. Thus, the optimized annealing temperature was selected as 600℃ because the NiFe₂O₄ obtained at 600℃(N600) exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m²/kg and the lowest coercivity(H_c) of 8914 A/m.     

Synthesis of manganese oxide electrodes with interconnected nanowire structure as an anode material for rechargeable lithium ion batteries

Manganese oxide electrodes composed of interconnected nanowires are electrochemically synthesized in manganous acetate solution at room temperature without any template and catalyst. Annealing temperature affects the electrode morphology, crystallization, and electrochemical performance. Scanning electron microscope (SEM) results show that nanowires are uniformly distributed and sizes are about 12-18 nm in diameter; the diameter decreases to about 8-12 nm after annealing at 300 degrees C. X-ray diffraction (XRD) and transmission electron microscope (TEM) images indicate that nanowires have poor crystalline characteristics. The higher the annealing temperature, the higher the crystalline degree is in manganese oxide. The synthesized anode material shows a much larger capacity than the traditional graphite materials for lithium storage. After annealing at 300 degrees C, the electrode's reversible capacity reaches 800 mAhg(-1), and the specific capacity retention remains nearly constant after 100 cycles.     

Porous ZnCo2O4 nanowires synthesis via sacrificial templates: high-performance anode materials of Li-ion batteries

A simple microemulsion-based method has been developed to synthesize ZnCo(2)(C(2)O(4))(3) nanowires that can be transformed to porous ZnCo(2)O(4) nanowires under annealing conditions. The morphology of porous ZnCo(2)O(4) nanowires can be tuned by the initial ZnCo(2)(C(2)O(4))(3) nanowires and the annealing temperatures. The as-synthesized porous ZnCo(2)O(4) nanowires have been applied as anode materials of Li-ion batteries, which show superior capacity and cycling performance. The porous one-dimensional (1D) nanostructures and large surface area are responsible for the superior performance. Moreover, it is indicated that porous ZnCo(2)O(4) nanowires synthesized at low annealing temperature (500 °C) show larger capacity and better cycling performance than that prepared at high annealing temperature (700 °C), because of their higher porosity and larger surface area.     

Disproportionation of thermoelectric bismuth telluride nanowires as a result of the annealing process

P-type thermoelectric bismuth telluride nanowires were fabricated by pulsed electrodeposition in anodic aluminium oxide (AAO) membranes. Subsequently, the nanowires were annealed at 423, 523 and 673 K in an inert atmosphere for 4 h. With increasing temperature, it was observed that the Te compound incongruently sublimates due to its high vapor pressure, leading to disproportionation (from Bi(2)Te(3) to Bi(4)Te(3)via Bi(4)Te(5)). The crystalline structure of the nanowires was then investigated using XRD and SAED, with nanowire compositions investigated using an EDX attached to a TEM. The crystallinity of the nanowires was found to be enhanced with increased annealing temperature, and nanowires annealed at 673 K were stably maintained in the Bi(4)Te(3) phase. Additionally, the Seebeck coefficient was determined and the thermopower of nanowires annealed at a temperature of 423 K was shown to be slightly enhanced. Significantly suppressed Seebeck values for annealing temperatures of 523 K and 673 K were also observed.     

Synthesis and characterization of highly ordered BiFeO3 multiferroic nanowire arrays

We report the synthesis and characterization of multiferroic BiFeO₃ (BFO) nanowires. The perovskite BFO nanowires with diameters about 60 nm and lengths about 10 μm were fabricated by means of the sol-gel method utilizing nanochannel alumina templates with post annealing at 700 °C. The microstructure of the BFO nanowires was investigated by means of x-ray diffraction and transmission electron microscopy, and the ferroelectric characteristic of BFO nanowires were demonstrated.     

Formation of well-aligned ZnGa(2)O(4) nanowires from Ga(2)O(3)/ZnO core-shell nanowires via a Ga(2)O(3)/ZnGa(2)O(4) epitaxial relationship

Formation of well-aligned and single-crystalline ZnGa(2)O(4) nanowires on sapphire (0001) substrates has been achieved via annealing of the Ga(2)O(3)/ZnO core-shell nanowires. Ga(2)O(3)/ZnO core-shell nanowires were prepared using a two-step method. The thickness of the original ZnO shell and the thermal budget of the annealing process play crucial roles for preparing single-crystalline ZnGa(2)O(4) nanowires. Structural analyses of the annealed nanowires reveal the existence of an epitaxial relationship between ZnGa(2)O(4) and Ga(2)O(3) phases during the solid-state reaction. A strong CL emission band centered at 360 nm and a small tail at 680 nm are obtained at room temperature from the single-crystalline ZnGa(2)O(4) nanowires.