Fe纳米有序阵列的制备与磁学特性

采用电化学沉积法，在氧化铝模板中成功制备了直径50nm的Fe纳米线的高度有序阵列。纳米线的结构和磁学特性分别用透射电子显微镜（TEM），扫描电子显微镜（SEM），X射线衍射仪（XRD）和振动样品磁力计（VSM）测试。结果表明，Fe纳米线是以fcc结构存在。当外加磁场与纳米线的线轴平行时，测得的矫顽力为21000e，剩磁比为0．89，而当外加磁场与纳米线线轴垂直时，所测得的矫顽力仅为1600e，剩磁比为0．2。这表明纳米线阵列具有明显的各向异性，纳柴癌的易妯方向为纳粜姥姥妯方向．     

Magnetic Properties and Reversal Modes of Electrodeposited CoCr Nanowire Arrays with Different Diameters

Journal of Superconductivity and Novel Magnetism - The better understanding of magnetization reversal in impurity added magnetic nanowires (NWs) would allow for their efficient use in future...     

Magnetic Properties of Diluted Magnetic Nanowire

A magnetic diluted nanowire with cylindrical structure described by the Ising model is investigated. Using the effective field theory with a probability distribution technique, the influence of the dilution on the phase diagrams, susceptibility and the hysteresis loops are discussed in detail. Novel features are obtained for the thermal variations of longitudinal susceptibility and longitudinal magnetization. We have investigated the magnetic reversal of the system and have found the existence of triple hysteresis loops patterns, affected by the concentration of magnetic atoms, the temperature, and the exchange interaction between the core and the surface shell.     

Preparation and Photoluminescence of Ordered ZnO Nanowire Arrays

Ordered ZnO nanowire arrays embedded in anodic aluminum oxide (AAO) membranes were fabricated by electrochemical deposition of Zn(NO3)2 H3BO3 solution in a boiling bath. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observation results show that the polycrystalline ZnO nanowires with diameters around 100 nm were uniformly assembled into the ordered nanochannels of the AAO. The results of the investigation into photoluminescence (PL) and electronic paramagnetic resonance (EPR) measurements reveal that the interfaces between the ZnO nanowires and the pore walls of the AAO create a lot of oxygen vacancies, which are responsible for the green light emission (peaking around 512 nm) and the huge enhancement of the PL emission.     

高密度、直立金属纳米线有序阵列的制备

本文提供了一种简单、可控的制备直立纳米线阵列的方法。采用循环伏安法在多孔阳极氧化铝模板中电沉积了Ag、Cu、Au金属纳米线阵列。SEM图片证明模板孔洞的填充率非常高。XRD分析结果表明,纳米线阵列都具有面心立方结构。采用循环伏安法可以方便地调节电沉积时间,进而有效地调控金属纳米线的长径比。去除模板后发现,当纳米线的长径比较大时,纳米线易于倒塌,聚集在一起。当纳米线的长径比在一定范围时,易于获得高密度、直立在导电衬底上的纳米线阵列。     

Preparation and Photolunlinescence of Ordered ZnO Nanowire Arrays

Ordered ZnO nanowire arrays embedded in anodic aluminum oxide (AAO) membranes were fabricated by electrochemical deposition of Zn(NO3)2+H3BO3 solution in a boiling bath. Scanning electron microscope (SEM) and transmission electron microscope (TEM) observation results show that the polycrystalline ZnO nanowires with diameters around 100 nm were uniformly assembled into the ordered nanochannels of the AAO. The results of the investigation into photoluminescence (PL) and electronic paramagnetic resonance (EPR) measurements reveal that the interfaces between the ZnO nanowires and the pore walls of the AAO create a lot of oxygen vacancies, which are responsible for the green light emission (peaking around 512 nm) and the huge enhancement of the PL emission.     

硅基径向纳米线阵列的制备及其机理研究

采用金属辅助化学刻蚀(MACE)的方法在硅衬底上制备出尺寸可控、表面光滑的硅纳米线阵列.利用扫描电子显微镜等检测仪器对所制备的硅纳米线样品进行了表征,研究了附银时间和双氧水浓度等工艺参数对硅纳米线生长的影响.结果表明,在附银时间为60 s、双氧水浓度为1.0 mol/L条件下,能够得到较为均匀、规则的硅纳米线阵列.此外,探讨了银辅助刻蚀硅纳米线的形成机理.     

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。     

交流电化学沉积FeCo合金纳米线阵列及其磁性能研究

采用二步阳极氧化法制备孔结构高度有序的多孔氧化铝(AAO)模板。在不同Fe2+/Co2+摩尔比的电解液中,利用交流电化学沉积,在模板孔内成功制备了FeCo合金纳米线阵列。分别采用透射电子显微镜(TEM),场发射扫描电子显微镜(FE-SEM),X射线衍射仪(XRD)和震动样品磁强计(VSM)对样品的形貌,结构及磁学性能进行了表征。结果表明,制备的FeCo合金纳米线排列有序,粗细均匀;其直径与模板孔径一致,填充率较高,且具有明显的[110]择优取向。VSM测试结果表明,不同溶液浓度下制备的FeCo合金纳米线阵列均具有良好的垂直磁各向异性,易磁化轴沿着纳米线轴线方向。随着电解液Fe2+/Co2+摩尔比的不同,可在一定范围内对FeCo合金纳米线阵列的磁性进行调控,并对其原因进行了讨论。     

图案化ZnO纳米线阵列制备与应用的研究进展

综述了多种图案化制备ZnO纳米线阵列的技术,包括电子束光刻技术、纳米球蚀刻技术、激光干涉光刻技术、纳米压印技术和嵌段共聚物蚀刻技术等。介绍了图案化ZnO纳米线阵列在传感器、太阳能电池和UV检测器等功能器件中的应用进展,分析了图案化ZnO纳米线阵列制备与应用中的优点、意义及存在的问题,并展望了其未来发展趋势。     

定向硅纳米线阵列的场发射性质的研究及改进

本文测量了垂直基底方向生长的硅纳米线阵列的场发射性质,并研究了引入金对其场发射性质的影响.引入金后,硅纳米线阵列在10 μA/cm2时的开启电场从4.7 V/μm降到了2.3 V/μm,并且根据Fowler-Nordheim曲线斜率的变化,估算出纳米线阵列的功函数从3.6 eV降到了2.2 eV.     

Bi-based Nanowire and Nanojunction Arrays： Fabrication and Physical Properties

This article reviews the recent developments in the fabrication and properties of one-dimensional （1D） Bi-based nanostructures, including Bi, Sb, BixSb1-x and Bi2Te3 nanowire arrays, and Bi-Bi and Bi-Sb nanojunction arrays. In this article, we present an efiective method to fabricate Bi nanowire arrays with difierent diameters in anodic alumina membrane （AAM） with a single pore size by the pulsed electrodeposition. The fabrication of the high-filling and ordered Bi1-xSbx and Bi2Te3 single crystalline nanowire arrays, the Bi nanowire metalsemiconductor homojunction and Bi-Sb nanowire metal-semiconductor heterojunction arrays by the pulsed electrodeposition are reported. The factors controlling the composition, diameter, growth rate and orientation of the nanowires are analyzed, and the growth mechanism of the nanowire and nanojunction arrays are discussed together with the study of the electrical and thermal properties of Bi-based nanowires and nanojunctions.Finally, this review is concluded with some perspectives on the research directions and focuses in the Bi-based nanomaterials fields.     

Preparation and Magnetic Properties of FePt Nanodot Arrays Sputtering on AAO Templates

FePt nanodot arrays are the promising recording media for future super-high density magnetic recording because of their huge uniaxial magneto-crystalline anisotropy and good signal noise ratio. In this article, FePt nanodot arrays were successfully prepared on anodic aluminum oxide (AAO) templates by magnetron sputtering, and an Ag underlayer was proposed to improve the magnetic properties of FePt nanodot arrays. The dependences of Ag underlayer, annealing temperature, and pore diameter on the magnetic properties of FePt nanodot arrays were investigated. Using the AAO templates with pore diameter of 80 nm and annealing temperature of 600°C, the coercivity of Ag/FePt nanodot arrays is improved significantly to 10262 Oe.     

三维结构磷酸铁锂纳米线阵列的制备及其电化学性能

采用阳极氧化铝模板(AAO),通过溶胶-凝胶法制备出磷酸铁锂(LiFePO_4)纳米线阵列。场发射扫描电镜(FESEM)和透射电镜(TEM)表征均说明制得的LiFePO_4阵列是分散均匀且相互平行的。X射线衍射(XRD)和能谱图(EDS)表征均说明LiFePO_4纳米线是纯相橄榄石型结构。电化学性能测试表明纳米线阵列具有较好的循环稳定性,1C电流密度下循环100次后容量几乎不衰减,容量保持率为99.1%,10C电流密度下循环350次后容量保持率为91.6%。纳米线阵列的倍率性能较同等条件下制备的纳米粉体有较大提升,0.1C、10C电流密度下容量可分别达156.4mAh/g、106.9mAh/g。     

Perpendicular Magnetic Tunnel Junctions with CoFe/Pd Multilayer Electrodes and an MgO Barrier

We studied the magnetic and magnetoresistance characteristics of pseudospin-valve magnetic tunnel junctions (MTJs) based on CoFe/Pd multilayer electrodes with perpendicular magnetic anisotropy and an MgO barrier. The MTJs at annealing temperature (T _a) of 473 K showed a tunnel-magnetoresistance (TMR) ratio of 1.5%. An fcc (111)-oriented texture of the bottom and top Co₉₀Fe₁₀/Pd multilayer electrodes, together with an imperfectly crystallized MgO, were revealed by cross-sectional TEM images. The TMR properties of perpendicular MTJs with a Co₂₀Fe₆₀B₂₀ or Co₅₀Fe₅₀ layer inserted between the CoFe/Pd multilayer electrodes and the MgO barrier were also studied. The TMR ratio with Co₂₀Fe₆₀B₂₀ insertion was 1.7% at T _a= 473 K and monotonically decreased at T _a over 523 K. The TMR ratio with Co₅₀Fe₅₀ insertion increased up to 3% at T _a= 573 K and then decreased to 0.4% at T _a= 598 K. The influence of the Pd layer on CoFeB was studied by using the simplified structures of Pd/CoFeB/MgO/CoFeB/Pd and Ta/CoFeB/MgO/CoFeB/Ta with inplane anisotropy. A former structure with Pd resulted in reduced TMR ratio which decreases with increasing T _a, whereas MTJs with a Ta-based structure showed a monotonic increase of a TMR ratio. The low TMR ratio observed in Pd-containing structures appears to result from crystallization of CoFeB in an unfavorable crystal orientation.     

Study of Electronic and Magnetic Properties of MnAu Nanowire

Self-consistent ab initio calculations, based on density functional theory (DFT) approach and using full-potential linear augmented plane wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the MnAu nanowire. Polarized spin and spin-orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn layers in MnAu nanowire. Magnetic moments considered to lie along the c-axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest neighbour Ising model on a MnAu nanowire is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different layers. The exchanges interactions between the magnetic atoms, the critical exponent associated with the magnetic susceptibility are obtained for MnAu nanowire with different layers.     

Temperature Dependence of Magnetic Properties of SmCo/FeCo Multilayer Films

1. IntroductionIn addition to the magnetic properties of each individual particle, intergrain illteraction play a dominantrole during demagnetization processes[1'2]. These intergrain interactions are sensitively influenced by intergranular phases depending on the respective preparation methodl3'4]. A systematic improvement of permanent magnets is only possible by a deeper understanding of the relations between intergrain interaction, microstructural features, and magnetic properties.In this pa…