不同结构镍纳米线阵列的制备及其磁性

采用直流电沉积在多孔有序氧化铝模板中制备了不同结构的有序镍纳米线阵列。采用SEM和TEM对所制备的镍纳米线的形貌和结构进行了表征。研究了镍纳米线不同结构对镍纳米线阵列磁性性能的影响规律．当电沉积电压为2．5V时制备的镍纳米线为多晶结构；电沉积电压4V时，镍纳米线为沿[220]择优取向的单晶结构；电沉积电压＞5V时，择优取向由[220]转为[111]方向．磁滞回线结果表明，单晶镍纳米线阵列与多晶纳米线阵列相比具有更高的矩形度，沿[111]择优取向的单晶纳米线相比沿[220]取向的单晶镍纳米线具有更大的矩形度，表现出显著的磁各向异性。     

基于p+-Si与n-ZnO纳米线的p-n异质结的制备及其性质研究

利用CVD蒸汽俘获法，在p^＋硅片上制备了垂直生长的n型ZnO纳米线阵列，用XRD和SEM分析了样品的结构与形貌。测试发现样品的I-V曲线符合典型的p-n异质结特性，正向开启电压为0．5V，反向饱和电流为0．02mA。计算了异质结的理想因子η，发现当异质结两端偏压在0V-0．3V的低压区域，理想因子为1．85，而在0．3v-0．8v的高偏压区域，理想因子为8．36。解释了理想因子偏高的原因是由于金属一半导体接触以及ZnO纳米线与p^＋-si界而存在缺陷。     

不同结构镍纳米线阵列的制备及其磁性

采用直流电沉积在多孔有序氧化铝模板中制备了不同结构的有序镍纳米线阵列。采用扫描电子显微镜和透射电子显微镜对所制备的镍纳米线的形貌和结构进行了表征。研究了镍纳米线不同结构对镍纳米线阵列磁性性能的影响规律。当电沉积电压为2.5V时制备的镍纳米线为多晶结构;电沉积电压4V时,镍纳米线为沿[220]择优取向的单晶结构;电沉积电压大于5V时,择优取向由[220]转为[111]方向。磁滞回线结果表明,单晶镍纳米线阵列与多晶纳米线阵列相比具有更高的矩形度,沿[111]择优取向的单晶纳米线相比沿[220]取向的单晶镍纳米线具有更大的矩形度,表现出显著的磁各向异性。     

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.     

复合锌镍纳米线结构和磁性研究

采用直流电化学沉积方法,在多孔阳极氧化铝模板纳米孔洞中制备出直径约90nm,长度超过10μm的金属Ni/Zn纳米线有序阵列.通过扫描电子显微镜(SEM),透射电子显微镜(TEM),原子力显微镜(AFM),X射线衍射仪(XRD),振动样品磁强计(VSM)对模板及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Ni/Zn纳米线具有沿[111]方向择优生长特性,易磁化方向沿纳米线长轴方向.     

镍-钴／镍／镍-钴镀层的制备及电化学性能

采用直流和脉冲方法电沉积了镍-钴／镍／镍-钴多层镀层。通过SEM对镍-钴／钞镍-钴镀层的微观结构进行了表征,采用Tafel曲线外推法、交流阻抗法、阳极极化曲线法等方法对镍-钴／镍／镍-钴镀层在0．1mol／LH2SO4和1％NaCl混合溶液及10％NaOH溶液中的耐腐蚀性能进行了表征。结果显示：镍-钴／镍／镍-钴镀层的表面致密均一;在0．1mol／LH2SO4＋1％NaCl溶液中的腐蚀电位最正,传质电阻最大达到i642Q·cm2;在10％NaOH中钝化区为542mV,具有较好的钝化效果。     

Heusler合金磁性纳米线的制备方法及磁性的研究进展

磁性纳米线发展至今,已在高密度垂直磁性存储器、传感器、生物医学、催化剂等领域得到广泛应用.其中,Heusler合金磁性纳米线(Heu-sler alloy magnetic nanowires,HAMNWs)因其优异的性能备受关注.然而,目前HAMNWs制备工艺尚未成熟,存在组分偏差、结构无序、形貌不均等问题,阻碍了其基本物理性质的研究和功能器件的应用设计.当前已有的HAMNWs制备方法包括扩散驱动退火法、模板辅助法、化学合成退火法、分子束外延法、静电纺丝法、电沉积法等,这些方法各有其优势和缺陷.其中,SBA-15模板辅助的化学合成退火法制备的HAMNWs组分精确、结构高度有序,但该模板与AAO模板相比,孔道均一性相对较差,导致纳米线形貌均一性和有序性较弱;分子束外延法可以实现纳米线以原子级精度生长,然而,其制备设备昂贵、操作复杂,难以推广普及;扩散驱动退火法主要针对二元核壳型HAMNWs,而对于三元HAMNWs,其适用难度较大;静电纺丝法对组分和结构的控制较好,但对纳米线的形貌均一性控制较弱,整体呈纤维状;电沉积法制备的纳米线形貌均一可控,但对于含有难共沉积元素的合金纳米线,其组分和结构控制都较差.本文综述了HAMNWs的制备方法,详细对比了各种方法的优缺点;重点针对直流、脉冲、交流电沉积法制备过程中不同的生长机理进行了讨论,并在此基础上分析了纳米线生长过程中各种因素的影响与调控.同时还对纳米线的基本物理性质和磁性参数进行了归纳总结,最后对未来HAMN-Ws的制备及应用发展进行了展望.     

基于模板电沉积法的坡莫合金纳米线制备研究进展

圆柱形坡莫合金纳米线具有单轴形状各向异性以及超高速磁畴壁输运特性,在微磁学研究和超高密度磁存储领域备受关注。因此,研究高质量圆柱形坡莫合金纳米线的制备技术具有十分重要的意义。目前在圆柱形坡莫合金纳米线制备方面,基于模板电沉积法成为了首选方式。由于各种电沉积参数对镍铁合金异常共沉积行为的影响,至今仍无法制备出镍铁成分配比一致以及致密性好的高质量纳米线。本文通过分析基于模板电沉积法的技术难点和原因,总结出可行的解决方案,为高质量坡莫合金纳米线的制备技术提供了参考。     

镍纳米管阵列的电沉积合成及其磁学性能表征

以氧化铝膜为模板、金属汞为电阴极,采用简单的直流电沉积方法制备出高度有序的镍纳米管阵列。利用扫描电子显微镜、透射电子显微镜、选区电子衍射、能谱仪、X射线粉末衍射和样品振动磁强计对样品进行形貌表征、成分及磁性能分析。结果表明,阵列中的镍纳米管彼此平行,尺寸均匀,纳米管外径为260～360nm;镍纳米管阵列表现出良好的磁各向异性,其易磁化方向垂直于镍纳米管阵列。以金属汞为电阴极是易形成纳米管的关键条件。     

Co88Ni12合金纳米线阵列的制备与磁性能表征

采用直流电化学沉积方法，在多孔阳极氧化铝模板的纳米级微孔内电沉积钴镍合金，制备出直径为30nm，长度为几个微米的准一维合金纳米线（阵列）材料；随后采用场发射扫描电子显微镜（FE-SEM），透射电子显微镜（TEM），X射线衍射仪（XRD），振动样品磁强计（VSM）对纳米线的形貌、结构及其磁性能进行了相关表征与测试．发现所制备的Co88Ni12合金纳米线表面光滑，粗细均一，具有较高的长径比；呈现密排六方结构（hcp），沿[100]择优取向生长，易磁化方向沿纳米线轴向方向．     

喷射电沉积纳米Ni/Co多层镀层及其组织性能

目前,纳米金属多层膜的研究体系和应用范围有待扩展,镀层成形机理、强化机理等方面有待深入研究。利用喷射电沉积技术制备了不同调制周期(λ)的Ni/Co纳米多层镀层,并对镀层的表面形貌与组织、显微硬度、耐磨损性能进行了测试与分析。结果表明:多层镀层各层之间有明显界限,镀层致密均匀,与低碳钢结合牢固;随着λ的减小,Ni/Co多层镀层表面越来越致密,镀层越来越平整;Ni/Co多层镀层结构的硬度和耐磨性明显优于纯Co镀层和纯Ni镀层;λ为20 nm时,Ni/Co多层镀层的硬度和耐磨损性能最好。     

Facile Synthesis of Bimetallic Ag/Ni Core/Sheath Nanowires and Their Magnetic and Electrical Properties

This paper describes a facile method for coating Ag nanowires with uniform, ferromagnetic sheaths made of polycrystalline Ni. A typical sample of these core/sheath nanowires had a saturation magnetization around 33 emu g^?1. We also demonstrated the use of this magnetic property to align the nanowires by simply placing a suspension of the nanowires on a substrate in a magnetic field and allowing the solvent to evaporate. The electrical conductivity of these core/sheath nanowires (2 × 10³ S cm^?1) was two orders of magnitude lower than that of bulk Ag (6.3 × 10⁵ S cm^?1) and Ni (1.4 × 10⁵ S cm^?1). This is likely caused by the transfer of electrons from the Ag core to the Ni sheath due to the difference in work function between the two metals. The electrons are expected to experience an increased resistance due to spin‐dependent scattering caused by the randomized magnetic domains in the polycrystalline, ferromagnetic Ni sheath. Studies on the structural changes to the Ni coating over time under different storage conditions show that storage of the nanowires on a substrate under ambient conditions leads to very little Ni oxidation after 6 months. These Ag/Ni core/sheath nanowires show promise in areas such as electronics, spintronics, and displays.     

磁性金属纳米结构的制备与表征

采用电化学沉积方法成功地制备了高度有序的镍纳米管/线阵列结构,并用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射(XRD)对产物的微观形貌和化学结构进行了表征和分析.测试结果显示,镍纳米结构阵列规整,镍纳米管壁具有多晶体结构;X射线衍射图谱表明,镍纳米管壁具有较高的结晶度.研究了沉积时间对镍纳米结构的影响.     

Exploring the Magnetic Properties of Individual Barcode Nanowires using Wide-Field Diamond Microscopy

A barcode magnetic nanowire typically comprises a multilayer magnetic structure in a single body with more than one segment type. Interestingly, due to selective functionalization and novel interactions between the layers, it has attracted significant attention, particularly in bioengineering. However, analyzing the magnetic properties at the individual nanowire level remains challenging. Herein, the characterization of a single magnetic nanowire is investigated at room temperature under ambient conditions based on magnetic images obtained via wide-field quantum microscopy with nitrogen-vacancy centers in diamond. Consequently, critical magnetic properties of a single nanowire can be extracted, such as saturation magnetization and coercivity, by comparing the experimental result with that of micromagnetic simulation. This study opens up the possibility for a versatile in situ characterization method suited to individual magnetic nanowires.     

铜纳米线的合成及其催化性能

利用多孔氧化铝(AAO)模板经交流电沉积制备得到了铜纳米线阵列,扫描电子显微镜(SEM)、能谱仪(EDS)分析结果表明:其长度在1~2μm,直径在60~80nm之间。利用制备的铜纳米线催化生长了纳米碳纤维阵列(VACNFs),利用SEM对VACNFs的形貌进行了表征,结果表明,所制备的VACNFs呈现阵列状分布,每根纤维垂直基底直立生长,在纤维末端距离较近的纤维之间相互吸引缠绕形成纤维束。最后分析了纳米碳纤维阵列的生长机制并提出了生长模型。     

Submicron particles of Co, Ni and Co-Ni alloys

Magnetic sub-micron sized particles (with diameters in the range 100–600 nm) of Co, Ni and Co-Ni alloys, protected with polyvinylpyrrolidone have been prepared in gram quantities using the polyol process. Experiments carried out with different metal precursors and starting compositions have yielded reliable routes to produce particles of the desired diameters in the 100–600 nm range. The particles were characterized with X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, thermogravimetric analysis and magnetic measurements. The particles are found to be stable under ambient conditions indefinitely. The coercivity values of the Co and Ni particles are ∼50% higher compared to the corresponding bulk values. The alloy particles follow a trend similar to the bulk alloys.     

Influence of Co Content on Raman and Photoluminescence Spectra of Co Doped ZnO Nanowires

Co doped ZnO nanowires with different Co contents have been fabricated by a chemical vapor deposition method. X-ray diffraction results show that all the samples are of single phase and crystallize in wurtzite ZnO structure. The lattice parameter a increases with increasing Co content, while the parameter c has no obvious change with increasing Co. Raman spectra show that the nonpolar E2(High) mode becomes broad and weak with the doping of Co, which indicates that the incorporation of Co causes structural disorder in the crystalline columnar ZnO lattice. The photoluminescence spectra exhibit that the position of the ultraviolet emission shifts to short wavelength and the intensity decreases with increasing Co. The green emission is affected by two contrary factors. It is increased by the introduced defects, but suppressed by the interaction between Co doping and native defects and the later affects it more significantly.     

Fe0.3Co0.7纳米有序阵列的制备和磁性

使用小孔径阳极氧化铝模板制备Fe0.3Co0.7纳米线有序阵列,研究了热处理对其磁性的影响.结果表明,热处理对Fe0.3Co0.7纳米线有序阵列的结晶度和局部形状各向异性有重大的影响,导致纳米阵列的矫顽力和剩磁比发生相应的变化.在适当热处理条件下获得的Fe0.3Co0.7纳米线有序阵列具有较高的矫顽力和剩磁比.在H2保护下550℃处理时获得最高的矫顽力2.63×105 A/m,矫顽力随着热处理时间的增加先是快速增加,然后趋向平缓,最后有一定程度的下降.     

铁钴镍基非晶态软磁材料的研究

研究了１０钟以铁钴镍为基的非昌态软磁材料，对非晶态合金的成分，熔点，晶化温度，居里温度及一些磁性能作了分析比较、将将材料制成元件装到电子镇流器上试验，研究结果表明，铁磁元素铁钴镍的含量比例，是影响非晶态磁性的主要因素；类金属元素对软磁材料的磁性能也有一定的影响，含磷的非晶态合金的熔点，晶化温度及居里温度比含碳的较高。