钴纳米线阵列的制备和磁性

在具有纳米孔洞的氧化铝模板上 ,用电化学的方法制备了钴纳米线有序阵列 ,磁性测量显示易磁化方向平行于纳米线 ,矫顽力较块材有很大提高 ,可作为垂直磁存储介质 ,理想的存储密度高达 2 .6× 10 10 /cm2     

(Sr_(0.1)Ca_(0.9))_(0.97)TiO_3∶Eu_(0.03)~(3+)荧光粉掺杂复合发光玻璃的制备与研究

玻璃具有透明、耐腐蚀等优点,是一种良好的基质材料。本文选用了TeO_2-ZnO、Bi_2O_3-ZnO-B_2O_3两种低熔点玻璃基体,掺杂(Sr_(0.1)Ca_(0.9))_(0.97)TiO_3∶Eu_(0.03)~(3+)荧光粉制备复合发光玻璃。研究表明,荧光粉在玻璃基体中的分散均匀性也受多种因素限制;荧光粉掺入玻璃基体中,受玻璃本身光散射的影响,发光性能受到了较大的限制。复合玻璃发光强度随着荧光粉掺杂量的增加而升高,但掺杂量超过一定值后,发光性能反而降低。掺杂量增加到一定程度时,得到的产物是烧结态陶瓷结构,其结构的变化降低了发光性能。对比TeO_2-ZnO、Bi_2O_3-ZnO-B_2O_3两种玻璃基体,TeO_2-ZnO玻璃与(Sr_(0.1)Ca_(0.9))_(0.97)TiO_3∶Eu_(0.03)~(3+)荧光粉有更好的匹配性。     

钙钛矿型混合导体BaCo_(0.7)Fe_(0.2)Nb_(0.1)O_(3-δ)的透氧性能

采用高温固相反应法制备钙钛矿型混合导体BaCo0.7Fe0.2Nb0.1O3-δ(BCFN)透氧膜,并通过SEM、XRD、O2-TPD等手段进行表征。实验考察了空气速率、氦气速率及温度对BCFN膜片透氧量的影响。研究发现膜的透氧量取决于两侧的氧分压差和氧离子在体相内的扩散。XRD的结果表明使用前后材料的相结构没有变化,证明BCFN作为透氧膜材料具有实际应用前景。     

不规则铁磁纳米线阵列的平均截止温度:静磁相互作用的影响

利用蒙特卡洛方法数值计算了不规则铁磁纳米线阵列的平均截止温度,重点考察了静磁相互作用的影响。纳米线组成三角形点阵,纳米线长度满足高斯分布。推导出非均匀纳米线间的静磁相互作用的解析表达式,在此基础上得到截止温度满足的解析方程。结果表明,纳米线长度分布宽度越大,系统的截止温度越小,即系统越不稳定。另外纳米线间的长程静磁相互作用也有利于系统的稳定。数值试验证明我们决定截止温度的方法简单精确,对纳米线长度涨落敏感,利用这种方法对系统稳定性的分析结果与前人相符。     

Fe21Ni79合金纳米线阵列的制备与磁性

用交流电化学沉积方法,在多孔铝阳极氧化膜的柱形孔内制备直径约60 nm,长度约为9.7 μm的Fe₂₁Ni₇₉合金纳米线.采用扫描电镜、透射电镜、X射线衍射仪和振动样品磁强计对纳米线的形貌 、结构和磁学性质进行了测试.结果表明,Fe₂₁Ni₇₉纳米线排列有序,长径比可控,合金呈fcc结构.当将其在外磁场下进行垂直磁化时,磁滞回线出现较高的矩形比0.86,矫顽力达1203Oe.且随着退火温度升高,矫顽力迅速增大,500℃时达到最大值1315Oe,之后又随退火温度的升高而下降.矩形比也呈现类似的变化规律.     

磁性纳米线阵列的制备与应用

介绍了以多孔氧化铝(AAO)和刻蚀高聚物为模板制备磁性纳米线阵列的方法,包括溶胶-凝胶法、化学沉积法和电沉积法等.结合磁性纳米线的研究现状,展望了磁性纳米线阵列在磁记录、巨磁电阻、量子磁盘和高密度磁存储等方面的应用前景.     

Fe_3O_4/P(St/ACPA)磁性高分子纳米球的制备与磁性能研究

采用化学共沉淀方法制备Fe_3O_4磁性粒子,并使用油酸和十一烯酸对其进行表面改性,然后采用一步细乳液聚合法制备含有羧基官能团的Fe_3O_4/P(St/ACPA)磁性高分子纳米球,对磁流体和磁性高分子纳米球进行性能表征。结果表明,改性的Fe_3O_4磁流体分散性好,粒径均一,在室温下呈超顺磁性,磁含量为68.5%(w),饱和磁化强度为51.3emu/g;Fe_3O_4/P(St/ACPA)磁性高分子纳米球成球性好,粒径为70 nm,磁含量为39%(w),饱和磁化强度为27.9 emu/g。     

Ni_(79)-Fe_(21)合金纳米线的电化学制备与表征

以多孔氧化铝为模板,采用控电位沉积方法制备了Ni-Fe纳米线及其阵列。能谱分析表明,纳米线组成为Ni79-Fe21。X-射线衍射测试表明,Ni-Fe纳米线呈面心立方Ni固溶体结构。磁滞回线测试表明,控电位制备的Ni-Fe纳米线阵列具有良好的软磁性能,500℃退火处理后,Ni-Fe合金纳米线具有硬磁性。     

银纳米线薄膜玻璃的制备及偏振性能研究

在玻璃表面镀膜是一种通过表面改性获得功能玻璃的有效方法,采用提拉工艺在玻璃表面制备具有高度取向的银纳米线薄膜。利用紫外可见光度分光仪和超景深三维视频显微镜等设备研究不同银纳米线含量、提拉速率对玻璃透过率、消光比等光学性能的影响。结果表明：银纳米线薄膜玻璃在银纳米线质量分数为2%、拉提速率为20 mm/min时,消光比在530 nm处达到24.2 dB,且在500～1 050 nm波长范围内消光比值达到20 dB以上,此时银纳米线薄膜玻璃的整体偏振性能最佳。这种制备方法有望降低大规模组装功能性纳米级电子和光子结构的成本。     

纳米阵列膜磁性质的蒙特卡罗模拟

计算机的模型数字模拟是进行新一代超高密度磁记录材料的研究和开发的重要手段。本文介绍了利用蒙特卡罗方法研究纳米阵列膜的磁性质的基本思想、目前取得的主要结果、面临的问题和可能的解决办法。     

CoPt_3纳米线阵列的制备及特性研究

在具有纳米级孔洞的多孔氧化铝模板上,用电化学方法成功地制备了CoPt3纳米线有序阵列复合膜。分别用透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线衍射(XRD)、振动样品磁强计(VSM)和SQUID对样品进行了测试与表征。形貌观察和物相分析表明,模板中的CoPt3纳米线构成的阵列,排列均匀有序,长约1.5微米,直径35纳米;而纳米线中的CoPt3为L12无序结构。磁性研究表明,纳米线的无序晶体结构决定了纳米线阵列弱的磁晶各向异性;同时纳米线中部分小晶粒在400K左右表现出顺磁性,导致纳米线阵列居里温度的下降。比较低温和室温下的磁滞回线,低温下有大的矫顽力,从另一方面证明纳米线中的小晶粒确实存在相转变。     

一维铂纳米线阵列的模板电沉积及其表征

将一种复合无机介孔膜作为新型的模板应用于一维纳米线阵列的模板合成研究中,通过采用模板恒电位沉积的方法制备出一维铂纳米线阵列,并利用扫描电镜,透射电镜,X射线衍射,能量分布谱,选区电子衍射对该铂纳米线阵列进行了表征。结果表明:通过模板恒电位沉积的方法可以将金属铂组装在复合无机介孔膜内的二氧化硅介孔管中,除去模板后,进而得到长度为10μm的一维多晶铂纳米线(半径为3～4nm)阵列。     

钕氟复合掺杂二氧化钛纳米线阵列的光催化性能

利用溶胶-电泳沉积技术,以多孔有序阳极氧化铝膜为模板制备Nd~(3+)/F~-共掺杂的二氧化钛纳米线阵列.用扫描电子显微镜、X射线衍射仪对其进行表征,并以甲基橙为降解物,对Nd~(3+)单掺杂TiO_2、F~-单掺杂TiO_2和Nd~(3+)/F~-共掺杂TiO_2进行了光催化降解性能研究.结果表明:Nd~(3+)/F~-共掺杂TiO_2纳米线阵列具有比单元素掺杂更高的光催化活性,光照1 h对甲基橙的降解率均达到90%以上.同时,杂质离子的引入使得TiO_2薄膜的吸收波长发生红移,实现了在不降低TiO_2光催化性能的同时又具有可见光活性.     

Synthesis,Magnetic Anisotropy and Optical Properties of Preferred Oriented Zinc Ferrite Nanowire Arrays

Preferred oriented ZnFe₂O₄ nanowire arrays with an average diameter of 16 nm were fabricated by post-annealing of ZnFe₂ nanowires within anodic aluminum oxide templates in atmosphere. Selected area electron diffraction and X-ray diffraction exhibit that the nanowires are in cubic spinel-type structure with a [110] preferred crystallite orientation. Magnetic measurement indicates that the as-prepared ZnFe₂O₄ nanowire arrays reveal uniaxial magnetic anisotropy, and the easy magnetization direction is parallel to the axis of nanowire. The optical properties show the ZnFe₂O₄ nanowire arrays give out 370–520 nm blue-violet light, and their UV absorption edge is around 700 nm. The estimated values of direct and indirect band gaps for the nanowires are 2.23 and 1.73 eV, respectively.     

Field Emission Properties and Fabrication of CdS Nanotube Arrays

A large area arrays (ca. 40 cm²) of CdS nanotube on silicon wafer are successfully fabricated by the method of layer-by-layer deposition cycle. The wall thicknesses of CdS nanotubes are tuned by controlling the times of layer-by-layer deposition cycle. The field emission (FE) properties of CdS nanotube arrays are investigated for the first time. The arrays of CdS nanotube with thin wall exhibit better FE properties, a lower turn-on field, and a higher field enhancement factor than that of the arrays of CdS nanotube with thick wall, for which the ratio of length to the wall thickness of the CdS nanotubes have played an important role. With increasing the wall thickness of CdS nanotube, the enhancement factor β decreases and the values of turn-on field and threshold field increase.     

Fabrication of Highly Ordered Polymeric Nanodot and Nanowire Arrays Templated by Supramolecular Assembly Block Copolymer Nanoporous Thin Films

Realizing the vast technological potential of patternable block copolymers requires both the precise controlling of the orientation and long-range ordering, which is still a challenging topic so far. Recently, we have demonstrated that ordered nanoporous thin film can be fabricated from a simple supramolecular assembly approach. Here we will extend this approach and provide a general route to fabricate large areas of highly ordered polymeric nanodot and nanowire arrays. We revealed that under a mixture solvent annealing atmosphere, a near-defect-free nanoporous thin film over large areas can be achieved. Under the direction of interpolymer hydrogen bonding and capillary action of nanopores, this ordered porous nanotemplate can be properly filled with phenolic resin precursor, followed by curation and pyrolysis at middle temperature to remove the nanotemplate, a perfect ordered polymer nanodot arrays replication was obtained. The orientation of the supramolecular assembly thin films can be readily re-aligned parallel to the substrate upon exposure to chloroform vapor, so this facile nanotemplate replica method can be further extend to generate large areas of polymeric nanowire arrays. Thus, we achieved a successful sub-30 nm patterns nanotemplates transfer methodology for fabricating polymeric nanopattern arrays with highly ordered structure and tunable morphologies.     

水热法制备Fe2O3微纳米材料及其磁性研究

以FeCl3为铁源,以PVP为表面活性剂,采用水热法,制备了氧化铁纳米材料.采用XRD、SEM、TEM和SQUID-VSM对样品进行了表征.结果随着反应时间的延长,产物的尺寸先是增大,随后由于发生了刻蚀而尺寸减小、其磁学性能也发生了相应的变化.说明反应时间对产物的形貌、尺寸和磁性影响较大.     

Fabrication and Properties of 2-2 Cement Based Piezoelectric Composites

Composites with 2-2 connectivity were fabricated from lead magnesium niobate-lead zirconate-lead titanate(PMN) and sulphoaluminate cement by cut-filling process. The influences of PMN volume fraction and water/cement ratio on the properties of the composite were investigated. The results show that the piezoelectric strain constant d₃₃ increase rapidly with increasing volume fraction of PMN. When the PMN volume fraction is about 0.60, the d₃₃ value is up to 357 pCN^-1. The planar electromechanical coupling coefficient K_p of the composites is lower than that of PMN ceramic, while the thickness electromechanical coupling coefficient K_t is higher than that of PMN ceramic. The water/cement ratio has little influence on piezoelectric properties of 2-2 cement based piezoelectric composite.     

聚丙烯/四氧化三铁纳米复合材料的制备、表征及磁性能研究

采用固态高速搅拌预混-熔融密炼过程制备了磁性聚丙烯(PP)/四氧化三铁(Fe3O4)纳米复合材料,并分别利用扫描电镜(SEM)、X射线衍射(XRD)、示差扫描量热仪(DSC)、热失重分析仪(TGA)和振动样品磁强计(VSM)对获得的复合材料的形貌、结构及磁性能进行了表征。结果显示:Fe3O4纳米粒子质量分数为5%时在聚合物基体中分散良好,基本呈单颗粒分散;随着Fe3O4含量的增加,粒子在PP基体中团聚程度加剧。Fe3O4和PP在复合材料中保持了各自的晶相结构,但是Fe3O4的加入降低了PP的结晶程度。同时,Fe3O4的加入提高了PP的热稳定性。振动样品磁强计(VSM)的结果表明:复合材料的饱和磁化强度(Ms)随Fe3O4含量的增加而增加,并呈线性的依赖关系;矫顽力(Hc)和剩余磁化强度(Mr)均很小,所制得的磁性纳米复合材料近似呈超顺磁性;该研究为磁性高分子纳米复合材料的制备提供了一种简单易行,Fe3O4纳米粒子在聚合物基体中良好分散,并且可以大批量生产磁性纳米复合材料的方法,并可能促进PP/Fe3O4纳米复合材料在电磁屏蔽和微波吸收等领域的应用。