多孔TiO2/Al/SiO2纳米复合结构的紫外光吸收特性研究

在SiO₂玻璃衬底上用脉冲激光沉积(PLD)技术,分别沉积Ti和Ti/Al膜,经电化学阳极氧化成功制备了多孔TiO₂/SiO₂和TiO₂/Al/SiO₂纳米复合结构. 其中TiO₂薄膜上的微孔阵列高度有序,分布均匀. 实验研究了Al过渡层对多孔TiO₂薄膜光吸收特性的影响. 结果表明：无Al过渡层的多孔TiO₂薄膜其紫外吸收峰在27 关键词： 2薄膜')" href="#">多孔TiO₂薄膜 阳极氧化 紫外光吸收     

多孔阳极氧化物的形成效率与纳米孔道的形成机理

多孔型阳极氧化铝（PAA）和多孔阳极氧化钛纳米管因其在诸多领域的广泛应用而备受关注．然而这类多孔阳极氧化物中纳米孔道的形成机理至今还不清楚,阳极氧化过程中电流一时间曲线与多孔形貌之间的关系至今无法解释．本文从致密型阳极氧化铝（CAA）的击穿机理入手,详细对比了CAA和PAA形成过程的区别与内在联系,从两种氧化膜电流．时间曲线（或电压一时间曲线）的分界点这个全新视角入手,找出了阳极氧化过程中氧化物形成效率下降的本质原因是电子电流的产生和氧气的析出．在CAA中球形孔洞的证据充分说明初期的规则孔洞是氧气气泡形成的．铝在混合电解液中阳极氧化的结果表明,一旦氧气析出停止,孔道生长就停止并被致密型的氧化物覆盖,一种新型的复合型氧化膜由此而得．最终结果表明：在PAN的形成过程中,适当的电子电流是氧气析出和孔洞形成的保证,适当的离子电流是氧化物形成和孔壁生长的保证．     

微米/纳米技术军事应用潜力巨大

 微米/纳米技术包括从亚毫米到亚微米尺寸的材料、工艺和器件的综合和集成技术,该技术领域将对航天工程、信息技术、制导武器、计算机、传感器探测技术、航空航天电子技术、雷达技术、隐身技术、微型机械设计与制造、微型光学自适应技术等诸多技术领域产生重大影响,其军事应用价值和潜力十分巨大!所以美国空军航天与导弹系统中心(SMC)从20世纪90年代初就开始预测微米/纳米技术在上述技术领域对未来空军武器装备系统和新系统结构发展的潜在影响。众所周知微电子技术发展曾使精确制导武器命中率提高2个数量级;使相控阵雷达功能提高了10×10³倍,平均无故障时间提高了230倍.     

水热法合成ZnO纳米棒图案及其场增强效应

利用水热合成方法在图案化的Au岛上合成了ZnO纳米棒图案,采用的溶液体系为六次甲基四胺和硝酸锌溶液,ZnO纳米棒的基底是ITO导电玻璃上的有序Au岛. 由于ZnO的异相成核速度在Au和ITO基底上具有不同的成核速度,因此ZnO优先生长在成核速度快的Au岛上,同时由于受到了溶液中前驱物种扩散的限制,纳米棒继续生长也被受到了约束. 通过调控六次甲基四胺和硝酸锌的浓度,可以调整不同的图案. 此外,利用X射线衍射、光致发光谱和场发射特性性能对水热合成的ZnO纳米棒图案进行了研究. ZnO纳米棒表现出良好的场增强性     

多孔TiO2/Al/SiO2纳米复合结构的紫外光吸收特性研究

在SiO₂玻璃衬底上用脉冲激光沉积(PLD)技术，分别沉积Ti和Ti/Al膜，经电化学阳极氧化成功制备了多孔TiO₂/SiO₂和TiO₂/Al/SiO₂纳米复合结构. 其中TiO₂薄膜上的微孔阵列高度有序，分布均匀. 实验研究了Al过渡层对多孔TiO₂薄膜光吸收特性的影响. 结果表明：无Al过渡层的多孔TiO₂薄膜其紫外吸收峰在27     

纳米隧道结的制备和特性研究

结合对向靶直流磁控溅射技术、微电子光刻方法和原子力显微镜阳极氧化加工方法制备了实用的纳米钛-钛氧化线-钛隧道结，钛膜的厚度为3.02nm.钛氧化线的宽度为60.5nm，在室温下此隧道结的I-V曲线表现出明显的库仑阻塞效应. 关键词： 原子力显微镜阳极氧化 钛氧化线 隧道结 库仑阻塞效应     

Nb/AlOx-Al/Nb超导隧道结制备氧化工艺与特性研究

提出一种氧的等离子氧化的方法改善结区边缘绝缘性能,降低超导隧道结的漏电流。对Al膜进行等离子氧化能够有效的改善氧化膜的绝缘性能,AES分析表明:氧化绝缘层均匀,界面清晰;应用此方法成功制备出较好性能的Nb隧道结。     

由纳米管和纳米颗粒构成的TiO2膜的制备与机理研究

采用聚苯乙烯小球修饰Ti片表面,并进行阳极氧化,制备出一种由纳米颗粒和纳米管构成的TiO₂膜．通过数值模拟,分析了氧化表面附近的局部电场分布对TiO₂膜形貌的影响．结果表明,覆盖物增强了局部电场,从而加快了O^2-与Ti的反应速率,有利于TiO₂的生长;与此同时,[TiF₆]^6-的扩散受到阻碍,使得TiO₂的溶解速率减慢．可见,覆盖物打破了TiO₂纳米管形成的平衡条件,导致纳米颗粒的生成．此外,通过X射线衍射和Raman光谱的测试分析发现,所制备的TiO₂为锐钛矿结构.     

Rh6G/氧化多孔硅复合膜的荧光光谱

为了发展性能良好的固体染料激光器,多孔介质中镶嵌激光染料是一种可行的途径。将氧化多孔硅作为基质材料,通过浸泡的方式将激光染料Rh6G嵌入其中,形成Rh6G/氧化多孔硅复合膜,对比研究了Rh6G在无水乙醇、多孔硅、多孔氧化硅中的荧光特性。结果表明,经高温氧化后,氧化多孔硅透明度提高,其荧光强度明显变弱,在复合膜中已检测不到其荧光行为。相比于在无水乙醇溶液中,在氧化多孔硅中Rh6G发射光谱的半峰全宽有所展宽,峰值波长略有红移,对称性大为提高,具有类似单体发光特性,这种现象与纳米孔对Rh6G的聚集程度的限制有关。     

有序Ti02纳米管阵列结构的可控生长及其物相研究

分别在HF水溶液、含NH4F和H2O的乙二醇有机溶液中对Ti箔进行阳极氧化,得到TiO2纳米管阵列结构.该结构高度有序、分布均匀、垂直取向,且通过阳极氧化工艺条件(如阳极氧化电压、电解液的选择与配比以及氧化时间等)可实现对其结构参数(如管径、管壁厚度、管密度、管长等)的有效控制.利用XRD研究了TiO2纳米管阵列的物相结构.结果表明:退火前的TiO2纳米管阵列为无定形结构;分别在真空和氧气氛中5I)0℃退火后,HF水溶液中制备的样品出现单一锐钛矿相,页在含NH4F和H2O的乙二醇有机溶液中氧化得到的样品则出现锐钛矿和金红石的混合相.前者在氧气氛中退火后锐钛矿晶化程度较高;后者在真空中退火后混合相的品化程度也较高.初步分析了TiO2纳米管阵列的形成机理.这些结果对基于TiO2,纳米管阵列的传感器及有机一无机异质结太阳电池的应用研究是非常有益的.     

Measurement of the double layer capacitance of aluminium samples by holographic interferometry

In the present investigation, holographic interferometry was utilized for the first time to measure the double layer capacitance of aluminium samples during the initial stage of anodization processes in an aqueous solution without any physical contact. The anodization process (oxidation) of the aluminium samples was carried out chemically in different sulphuric acid concentrations (0.5–3.125% H₂S0₄) at room temperature. In the meantime, a method of holographic interferometry was used to measure the thickness of anodization (oxide film) of the aluminium samples in aqueous solutions. Along with the holographic measurement, a mathematical model was derived in order to correlate the double layer capacitance of the aluminium samples in solutions to the thickness of the oxide film of the aluminium samples which forms due to the chemical oxidation. The thickness of the oxide film of the aluminium samples was measured by real-time holographic interferometry. Consequently, holographic interferometry is found to be very useful for surface finish industries, especially for monitoring the early stage of anodization processes of metals, in which the thickness of the anodized film as well as the double layer capacitance of the aluminium samples can be determined in situ. In addition, a comparison was made between the obtained data of the double layer capacitance from the holographic measurements and the double layer capacitance data obtained from measurements of electrochemical impedance spectroscopy. The comparison indicates that there is good agreement between the data from both techniques.     

Correlations among micro- and macromechanical properties of composite materials based on the interphase concept

In this paper an attempt was made to define microstructural properties of carbon fiber/PP composites, with respect to fiber surface chemistry and morphology. In order to define the effects of the fiber surface sizings and morphology on the polymer microstructure, the interphase and mechanical properties of the composites, carbon fibers with similar, but not identical surface chemistry (CH and CT) were used. Characterization was performed by several techniques: SEM, POM, reflection microscopy, DSC, FTIR, XPS, contact angle measurements. For microstructural analysis, the geometrical method, method of intercept and DIF method were used. It was found that both carbon fibers have a strong influence on the nucleation mechanism and crystallization as well as on the microstructural parameters in the model and macro composites. Nucleation efficiency of the fibers has been confirmed by the nucleation parameter Q, measured by Muchova–Lednicky method and by the interfacial energy parameters. Microstructural analysis based on the photographs obtained by POM, SEM and reflection microscopy has shown that in the CH/PP model and macrocomposites the sieve-grain network was formed, which indicates better mechanical properties. The results obtained for the macromechanical properties of PP composites reinforced with CH and CT have confirmed the prediction based on micostructural analysis.     

锂离子电池用具有分级三维离子电子混合导电网络结构的纳微复合电极材料

文章评述了分级三维离子电子混合导电网络结构和具有该结构的纳微复合电极材料在锂离子电池中的应用等方面的最新研究工作进展.首先介绍了纳微复合电极结构相关概念及其优缺点,然后列举了一些运用此概念设计并构筑出的电极材料实例.研究证明,此新型电极结构能够大幅提高锂离子电池电极材料的储锂性能,并且该结构设计还可推广到其他电化学储能...     

Three-dimensional magnetic properties of soft magnetic composite materials

A three-dimensional (3-D) magnetic property measurement system, which can control the three components of the magnetic flux density B vector and measure the magnetic field strength H vector in a cubic sample of soft magnetic material, has been developed and calibrated. This paper studies the relationship between the B and H loci in 3-D space, and the power losses features of a soft magnetic composite when the B loci are controlled to be circles with increasing magnitudes and ellipses evolving from a straight line to circle in three orthogonal planes. It is found that the B and H loci lie in the same magnetization plane, but the H loci and power losses strongly depend on the orientation, position, and process of magnetization. On the other hand, the H vector evolves into a unique locus, and the power loss approaches a unique value, respectively, when the B vector evolves into the round locus with the same magnitude from either a series of circles or ellipses.     

基于复合抖动技术的三维轮廓数据压缩方法

三维扫描技术获取的三维轮廓数据体积较大,不便于三维数字博物馆数据的实时传输和显示。针对这个问题,提出了基于复合抖动技术的三维轮廓数据压缩方法。首先,利用虚拟结构光投影系统实现三维轮廓数据的图像存储。然后,对图像的不同通道使用不同的抖动技术进行处理,并将结果保存到8位灰度图中主要的3位或者3幅1位逻辑图中,实现三维轮廓数据的进一步压缩存储。实验表明,与提供的三维模型格式相比提出方法的数据压缩比高达75.9∶1,非常适合三维轮廓数据的实时传输、重建与显示。     

Waterborne crackle decorative coatings and crack patterns

A preparation method of waterborne crackle decorative coatings was reported in this paper and the factors that influence crack patterns were investigated. The crackle coating consisted of a waterborne basecoat and a waterborne topcoat. The basecoat was made from two-component epoxy emulsion and the topcoat was made from fluorine-containing acrylic emulsion, silicone-acrylic emulsion or styrene-acrylic emulsion. Three junction types of crack patterns were prepared by the three top coatings, which were T-junction, Y-junction and mixed junction. T-junction type with long and straight cracks was prepared from styrene-acrylic emulsion 296DS. Y-junction type with curve and short cracks was prepared from fluorine-containing acrylic emulsion A603C and mixed junctions type was made from silicone-acrylic emulsion. Crack patterns with different spacing were prepared by controlling the thickness of topcoat, dryness of basecoat or conditions of film forming. The characterize methods of type and spacing for crack pattern were developed and properties of coating film including adhesion, water resistance, scrub resistance and so on were tested. The results showed that the crackle coatings possessed satisfactory properties for practical application.     

Large third—order optical nonlinearity in Au nanomeytre particle doped BaTiO3 composite films near the resonant frequency

Nanometre-sized gold particles embedded in BaTiO₃ composite thin films (Au/BaTiO₃) were fabricated by the pulsed laser deposition technique. The films were grown on MgO (100) substrates at 700℃. The crystalline property of the films was studied with x-ray diffraction. X-ray photoelectron spectroscopy was used to check the Au composition and chemical nature for the deposited films. The absorption peak due to the surface plasmon resonance of Au particles was observed at the wavelength of about 570 nm, which increased as the metal particle size was increased. The nonlinear optical properties of the Au/BaTiO₃ films were determined using the z-scan method at the wavelength of 532 nm, which was close to the resonant frequency. The real and imaginary parts of the third-order nonlinear susceptibility χ⁽³⁾ at an Au concentration of about 6.7 at.% were determined to be 6.62×10^-7 esu and -6.24×10^-8 esu, respectively. The films showed a very large absorption, masking the nonlinear refraction effect at high metal concentrations.     

Three-dimensional vector holograms in photoreactive polymer dissolved liquid crystal composite

A detailed analysis of three-dimensional vector holograms is presented which were recorded in a photoreactive polymer dissolved liquid crystal. The diffraction properties of resultant periodic anisotropic structures were investigated. Experimental observations confirmed that the diffraction efficiencies of the structures varied with slight changes of the grating pitch, and also that they strongly depended on the incident angle of the probe beam. These diffraction properties were explained by the finite-difference time-domain optical simulations.