AAO模板合成法制备金属Ni磁性纳米线阵列的研究

利用电化学沉积法,在AAO模板上制备了铁磁性金属Ni纳米线有序阵列.通过XRD、SEM等分析测试方法研究了制备工艺与Ni纳米线结构的关系,并在此基础上研究了结构对其磁性能的影响.在恒定沉积电压为-2 V时,适当的电流密度(2 mA/cm2)以及较长的沉积时间(9 h),有助于得到沿着[220]方向的高织构性纳米线.另外,相对于多晶结构,单晶或高织构性结构的Ni纳米线具有较高的矫顽力、剩磁及更显著的磁各向异性.     

核/壳结构Fe/FeS_2纳米线结构与磁性能

利用电沉积及热硫化法制备了核/壳结构Fe/FeS2纳米线,研究了硫化过程对纳米线体系磁特性的影响。试验中,通过直流电沉积方法,可以在纳米孔洞高度有序排布的阳极氧化铝模板中制备Fe纳米线,之后部分溶去模板,再经450℃硫化处理,Fe纳米线表面可形成＂毛刷＂绒状物FeS2,从而形成核/壳结构Fe/FeS2纳米线。结果表明,随着高温硫化处理,Fe纳米线直径略有减小,且择优取向发生变化,并引起复合纳米线饱和磁化强度及矫顽力增强,主要认为是由于核/壳复合结构的形成引起纳米线体系静磁耦合作用降低所致。     

Ni纳米线的制备及其微波吸收电磁性能

以氧化铝模板的孔洞为模型利用直流电沉积法制备了Ni纳米线.采用SEM,XRD,TEM对Ni纳米线的形貌和结构进行了表征.结果表明,Ni纳米线为单晶结构,沿[111]方向择优取向.把所制备的Ni纳米线和石蜡按质量比1∶1混合均匀后,利用同轴法测量其磁导率和介电常数,同时研究了该复合材料的吸波性能,计算得到了在不同厚度下的反射率曲线.研究发现,该纳米线/石蜡复合材料是一种介电损耗材料,在约9.5 GHz处介电损耗可达0.55,具有一定的吸波性能;当厚度为3mm时,在6.5 GHz处反射率可达-18 dB.     

化学沉积法制备铜纳米管与纳米线

以多孔氧化铝膜为模板,通过化学沉积法制备Cu纳米管与纳米线。分别用透射电子显微镜（TEM）、X射线衍射仪（XRD）对制备的样品进行了形貌分析与结构表征。结果表明,成功组装出Cu纳米管与纳米线。研究发现,Cu纳米管与纳米线制备成功与否取决于前处理过程中的还原步骤。Cu纳米管的外径与Cu纳米线的直径可通过改变模板制备工艺,进而改变模板孔径来调节;Cu纳米管的内径可由沉积时间的变化来控制。     

AAO模板法制备Pd-Ni合金纳米线

在孔深60gm，直径200nm的通孔氧化铝模板中，用60mmol·dm^-3。Pd（NH3）4Cl2＋40mmol·dm^-3NiSO4·6H2O＋0．2mol·dm^-3NH4Cl，pH8．5和70mmol·dm^-3。Pd（NH3）4Cl2＋30mmol-dm^-3NiSO4·6H2O＋0．2mol·dm^-3NH4Cl，pH8.5的2种电解液，采用直流电沉积的方法制备钯镍合金纳米线阵列。借助扫描电子显微镜（SEM）和X-射线能谱仪（EDX）表征纳米线的形貌和成分。结果表明，用-0．6V～-0．8V（vsSCE）的直流电沉积，在氧化铝（AAO）模板中可以成功地制备出镍含量在8％～15％（质量分数，下同）之间的Pd-Ni合金纳米线有序阵列，其直径和模板的孔径是一致的。沉积电势负移将使得电流密度增加，有利于合金中电势较负金属镍含量的增大。     

Co纳米阵列的制备及其直径对磁性的影响

采用电化学沉积法，在氧化铝模板中制备了不同直径的Co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（XRD）仪和振动样品磁力计（VSM）测试。结果表明，Co纳米线是以fcc和hcp结构同时存在。磁学性质研究表明，这种阵列具有较强的垂直磁各向异性。直径对纳米有序阵列磁学特性的影响研究表明，当直径超过100nm后，Co纳米线磁学性质与块体Co已经没有什么区别。     

Fe磁性纳米线阵列的制备与微波吸收性能研究

采用脉冲和直流电沉积方式，以FeSO4，（NH4）2SO4等混合溶液为电解液，在多孔阳极氧化铝模板（AAO模板）微孔内成功制备出Fe磁性纳米线阵列。用X射线衍射仪、扫描电镜及HP8510B网络分析仪对多孔AAO模板以及Fe磁性纳米线阵列的微观形貌、组织结构及微波吸收性能进行了测试。结果表明，沉积的纳米线为立方结构α=Fe，且纳米线阵列存在（110）择优取向性。Fe纳米线组装后的铝基AAO模板吸波材料具有良好的微波吸收效果，在2GHz～18GHz频段内的最大反射率为-4．8dB，大于-1dB的吸收带宽约为10GHz。     

模板法电化学沉积超长铜纳米线制备及其性能

用恒电位电化学沉积法，尝试在氧化铝模板纳米孔内制备超长铜纳米线。透射电子显微镜（TEM）和扫描电子显微镜（SEM）分析结果表明：在较低的沉积电位下，纳米线表面较为光滑且呈现条纹结构，直径均匀，大约100nm，线长可达40-50μm，放置一段时间后离解成颗粒状；较高沉积电位下，纳米线的边缘粗糙不平，主要由晶粒连接而成，晶粒之间有空隙存在。金属纳米线的生长实际上是金属颗粒的堆积过程，金属原子之间无较强的化学键存在。由X射线衍射（XRD）、高分辨透射电子显微镜（HRTEM）分析得知，低电位下所得纳米线为单晶结构，沿[111]方向生长，而高电位下则出现了孪晶结构。     

CoPt合金纳米有序阵列制备及热处理对其磁性的影响

用电化学沉积法,在阳极氧化铝模板（AAO）中成功制备了直径为φ50nm的CoPt合金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、扫描电子显微镜、X射线衍射仪和振动样品磁力计（VSM）测试。结果表明,CoPt合金纳米线是以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Hc为2400 Oe,剩磁比为0．75,而当外加磁场与纳米线线轴垂直时,所测得的矫顽力仅为600 Oe,剩磁比为0．25。这表明纳米线阵列具有明显的各向异性,纳米线的易轴方向为纳米线线轴方向。热处理过程中合金的微结构发生了变化,可以极大地提高材料的矫顽力。     

电沉积增材制造微镍柱的工艺研究

目的 探究电沉积工艺参数对无掩模定域性增材制造微镍柱的微观形貌、直径和沉积速率的影响.方法 采用尖锥形铂丝作为阳极、铜板作为阴极,电镀液从阳极和导流腔之间的微缝隙以射流方式流到阴极表面,电化学沉积增材制造微镍柱.采用体视显微镜和扫描电子显微镜对镍柱微观结构进行检测.通过单因素试验研究极间电压和初始极间距对微镍柱微观形貌、沉积速率和直径的影响规律.结果 初始极间距为10μm、电压为3.8～4.4 V时,可以制备出直径均匀、圆柱度较高的微镍柱;电压增至4.7 V时,微镍柱形状不规则,常伴有分叉现象或呈瘤状沉积.极间电压从3.8 V增加到4.7 V时,微镍柱体积沉积速率由539μm3/s增长至4159μm3/s,直径由55μm增长至102μm.此外,当极间电压为4.1 V、初始极间距为20～40μm时,随着初始极间距的增大,微镍柱顶端从圆柱形逐渐转向锥形沉积.结论 极间电压对微镍柱微观形貌、沉积速率和直径的影响明显,初始极间距主要影响微镍柱顶端的沉积生长形状.     

Novel dye-sensitized solar cell architecture using TiO_2-coated Ag nanowires array as photoanode

With the aim of reducing series resistance and increasing dye loading, novel dye-sensitized solar cell architecture was designed with TiO_2 nanoparticle-coated Ag nanowires array as the photoanode. Ag nanowire array was prepared by anodic aluminum oxide(AAO) templateassisted electrochemical deposition route. Then, Ag nanowires were coated by TiO_2 nanoparticles in hydrothermal process. The structures of the photoanode were characterized by field emission scanning electron microscopy(FESEM). Ag nanowires are covered by a layer of very fine nanoparticles with a diameter of less than 5 nm. X-ray diffraction(XRD) and selected-area electron diffraction(SAED) show that Ag nanowires have a strong preferred orientation in(220) direction and the TiO_2 coating layer is a polycrystalline structure. With this photoanode, 3.2%conversion efficiency is achieved for the cell sensitized with N3 dye.     

Synthesis and characterization ofsingle-crystalline alumina nanowires

Alumina nanowires were synthesized on large-area silicon substrate via simple thermal evaporation method of heating a mixture of aluminum and alumina powders without using any catalyst or template. The phase structure and the surface morphology of the as-grown sample were analyzed by X-ray diffractometry(XRD) and scanning electron microscopy (SEM), respectively. The chemical composition and the microstructure of the as-grown alumina nanowires were characterized using transmission electron microscope(TEM). The nanowires are usually straight and the single crystalline has average diameter of 40 nm and length of 3 - 5μm. The growth direction is along the [002] direction. Well aligned alumina nanowire arrays were observed on the surface of many large particles. The catalyst-free growth of the alumina nanowires was explained under the framework of a vapor-solid(VS) growth mechanism. This as-synthesized alumina nanowires could find potential applications in the fabrication of nanodevices.     

EFFECT OF Ar PRESSURE ON STRUCTURAL AND ELECTRICAL PROPERTIES OF Cu FILMS DEPOSITED ON GLASS BY DC MAGNETRON SPUTTERING

Cu films with thickness of 630-1300nm were deposited on glass substrates without heating by DC magnetron sputtering in pure Ar gas. Ar pressure was controlled to 0.5, 1.0 and 1.5Pa respectively. The target voltage was fixed at 500V but the target current increased from 200 to 1150mA with Ar pressure increasing. X-ray diffrac-tion, scanning electron microscopy and atomic force microscopy were used to observe the structural characterization of the films. The resistivity of the films was measured using four-point probe technique. At all the Ar pressures, the Cu films have mixture crystalline orientations of [111], [200] and [220] in the direction of the film growth. The film deposited at lower pressure shows more [111] orientation while that deposited at higher pressure has more [220] orientation. The amount of larger grains in the film prepared at 0.5Pa Ar pressure is slightly less than that prepared at 1.0Pa and 1.5Pa Ar pressures. The resistivities of the films prepared at three different Ar pressures re     

多弧离子镀负偏压对氮化钛薄膜的影响

目的确定适当的负偏压,提高多弧离子镀氮化钛薄膜的综合性能。方法采用不同的负偏压,在4Cr13不锈钢表面制备Ti N薄膜,探讨偏压对薄膜表面质量、结构、硬度、结合力和摩擦系数的影响。结果负偏压对薄膜表面质量的影响较大:负偏压为0 V时,Ti N薄膜表面凹凸不平,液滴较多;随着负偏压升高,薄膜表面变得光滑,液滴减少并变小,薄膜致密性也得到提高。在不同负偏压下,Ti N薄膜均呈现出在(111)晶面的择优取向,但随着负偏压的增大,这种择优取向逐渐减弱,当负偏压达到400 V时,薄膜在(220)晶面的峰值逐渐增强。随着负偏压从0增至400 V,薄膜的硬度、结合力和耐磨性均先提高,后降低。当负偏压为300 V时,薄膜的硬度和结合力达到最大,分别为2650HV和58 N;摩擦系数和磨损量最小,分别为0.48和0.1065 mm3。结论施加适当的负偏压可以提高薄膜的硬度、结合力、耐磨性等性能,当负偏压为300 V时,薄膜的各项性能达到最佳。     

沉积偏压对AlCrTiN纳米复合涂层力学与抗高温氧化性能的影响

沉积偏压对涂层的结构与性能具有重要影响,为研究其对AlCrTiN纳米复合涂层成分、组织结构、力学与抗高温氧化性能的影响规律,采用磁控溅射技术,改变沉积偏压(-30、-60、-90、-120 V)制备四种AlCrTiN纳米复合涂层。利用X射线衍射仪、扫描电子显微镜、纳米压痕仪等仪器表征涂层的组织结构、成分、力学性能和抗高温氧化性能。研究结果表明：不同偏压下制备的AlCrTiN纳米复合涂层均为NaCl型fcc-(Al,Cr,Ti)N相结构。随着沉积偏压增大,涂层由沿(111)晶面择优生长转变为无明显的择优生长取向,晶粒尺寸降低,残余应力和硬度增大。偏压为-90 V与-120 V时,涂层表面更加致密,具有更高的硬度和弹性模量。在800℃与900℃氧化1 h后,所有涂层表面均生成一层连续致密的Al₂O₃膜。随着沉积偏压增加,氧化膜厚度逐渐降低,表明抗高温氧化性能逐渐增强,这是因为高偏压下涂层组织更致密,且晶粒更细小。研究成果对AlCrTiN纳米复合涂层的综合性能提升与工程化应用具有一定指导意义。     

一步阳极氧化法制备氧化铝纳米线及其形成机理

采用一步恒压阳极氧化法在草酸电解液中制备氧化铝纳米线,用扫描电子显微镜和X射线衍射仪等对阳极氧化后产物的形貌、晶相进行了分析,研究了氧化电压、反应温度和电解质浓度对氧化产物形貌的影响。结果表明,纳米线的最佳制备条件为40℃、40 V、0.1 mol/L的草酸电解液。新制备的纳米线为无定形结构,在800℃煅烧60 min后转变为立方相氧化铝。同时根据实验结果,从反应界面的温度分布角度,对氧化铝纳米线的形成机理进行了探讨。     

Structural studies of metallic nanowires with synchrotron radiation

Mesoporous alumina membranes, with pore diameters between 5 and 100 nm, have been used as templates for the electrochemical deposition of nanowires of metals including gold, silver, iron and cobalt. Several absorption and scattering techniques using synchrotron X-ray radiation, including EXAFS, XANES, SAXS, WAXS and high-energy diffraction, have been used to study the structural features of the empty membranes and the confined metal nanowires. The results show that the membranes consist of arrays of highly-aligned parallel cylindrical pores with axes that are distributed on a disordered two-dimensional hexagonal lattice. Nanowires of gold, silver, and iron have the same lattice structures and almost identical interatomic distances as the corresponding bulk metals. Cobalt nanowires are composed of a mixture of h.c.p. and f.c.c. phases in a ratio depending on the pore diameter. The crystallites of the metallic nanowires show strong preferred orientation relative to the pore axis in the case of iron and cobalt but are more isotropic in the case of gold and silver. The results confirm the anisotropic behaviour of the materials but further theoretical work and additional modelling will be required to extract the full quantitative information from the available data. The powerful combination of complementary X-ray techniques shows the advantages of using third-generation synchrotron radiation for this type of structural investigation.     

恒压阳极氧化对镁合金氧化膜的影响

    研究了恒压条件下,电压对阳极氧化膜性能的影响.结果表明:恒压10V的阳极氧化,阳极表面没有电火花的产生,类似于普通的阳极氧化;而恒压15、20、25 V的阳极氧化,阳极表面有电火花产生,是微火花放电阶段;恒压10、15、20、25 V制得的阳极氧化膜主要成分是MgO,同时含有Al₂O₃以及Na4(AlSiO₄)₃(OH)、Al₂SiO₅、SiO₂等;从10 V到20 V,随着电压的提高,试样耐蚀性提高;25 V时电火花的强度较大,放电气孔平均孔径较大,降低了有效厚度,耐蚀性下降.     

Crystallographic Texture Evolution of ■-Fe_4N and Its Influences on Tribological Property of Nitrided Steel

The crystallographic texture of ■-Fe4 N in compound layer and its influences on the tribological properties of nitrided steel 38 Cr Mo Al are investigated in the study. The preferred orientation of(200)■ is produced by low-temperature nitriding in atmosphere with low nitrogen–hydrogen ratio and increases with the nitriding time. The preferred orientation of(220)■ appears after 72 h cyclic nitriding. The orientation relationships(0001)_ε//(101)_■ and [110]_ε//[111]_■,(111)_■//(0001)_ε and 011_■//[1■10]_g,(200)■//(110)_■ and [011]_■//[111]_■, as well as (1■03)_ε //(220)_■ and [0100]_ε//[1■0]_■ are established by first-principles method. The misfit of interatomic distance(δ), determining the phase transition resistance, is calculated. Accordingly, two reaction pathways during nitriding, ■→■ and ■→ε→■, are assumed, which determines the preferred orientations of ■-Fe_4 N. Results of wear tests demonstrate that the specimen with preferred orientation of(200)■ exhibits lower frictional coefficient and lower wear rate in comparison with the specimen with(220)■ preferred orientation.(111)■ texture usually relates to the lower frictional coefficient but higher wear rate due to the main slip system parallel to the sliding plane. Therefore, the(200)■ preferred orientation has a positive significance in improving the wear properties of steels.