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硅和氧化硅与贵金属金和银不互熔，因此，把硅氧化物同贵金属共蒸发可以用来制取各种硅纳米结构．如果把SiO和Ag2O一起蒸发到温度保持在Ag熔点以上（比如说，1000℃）的衬底上，则会形成Ag为内核、SiO2为外壳的内核／壳层结构．根据壳层几何形状的不同，其上由冷却造成的应力分布花样可以是三角铺排、菲波纳契螺旋、草莓上的“X形”点阵等花样（Li＆Cao，Science 309，909（2005））．     

球面上皱褶花样的演化

文章从理论和实验两方面研究了通过控制柔性衬底的曲率来调控球面上应力诱导之皱褶花样的可行性.研究以Ag内核/SiO2壳层微结构为对象.结果表明,当球形衬底的曲率较小且应力刚超过临界值时,皱褶花样为三角铺排的凹痕结构;而当应力进一步增大和/或衬底的半径增大时,则出现迷宫形的花样.皱褶的周期长度和临界屈曲应力都随衬底半径的增大而增大.此方向上的研究对于理解大自然中许多花样(比如花叶序与皱纹)的产生和演化具有重要的意义.     

受限于纳米孔的星型ABC三嵌段共聚物自组装形成核-壳-柱状相

在不同条件、不同形状与尺寸孔隙下,星型ABC三嵌段共聚物自组装形成的核-壳-柱状相的相行为,纳米结构形成与小孔几何形状有关,不同表面势能对星型ABC三嵌段共聚物的自组装过程有影响.     

ZrO2/SiO2多层膜中膜厚组合周期数及基底材料对残余应力的影响

ZrO2/SiO2多层膜由相同沉积条件下的电子束蒸发方法制备而成,通过改变多层膜中高(ZrO2)、低(SiO2)折射率材料膜厚组合周期数的方法,研究了沉积在熔石英和BK7玻璃基底上多层膜中残余应力的变化.用ZYGO光学干涉仪测量了基底镀膜前后曲率半径的变化,并确定了薄膜中的残余应力.结果发现,该多层膜中的残余应力为压应力,随着薄膜中膜厚组合周期数的增加,压应力值逐渐减小.而且在相同条件下,石英基底上所沉积多层膜中的压应力值要小于BK7玻璃基底上所沉积多层膜中的压应力值.用x射线衍射技术测量分析了膜厚组合周期数不同的ZrO2/SiO2多层膜微结构,发现随着周期数增加,多层膜的结晶程度增强.同时多层膜的微结构应变表现出了与所测应力不一致的变化趋势,这主要是由多层膜中,膜层界面之间复杂的相互作用引起的.     

ZrO2／SiO2多层膜中膜厚组合周期数及基底材料对残余应力的影响

ZrO₂／SiO₂多层膜由相同沉积条件下的电子束蒸发方法制备而成， 通过改变多层膜中高(ZrO₂)、低(SiO₂)折射率材料膜厚组合周期数的方法，研究了沉积 在熔石英和BK7玻璃 基底上多层膜中残余应力的变化. 用ZYGO光学干涉仪测量了基底镀膜前后曲率半径的变化， 并确定了薄膜中的残余应力. 结果发现，该多层膜中的残余应力为压应力，随着薄膜中膜厚 组合周期数的增加，压应力值逐渐减小. 而且在相同条件下，石英基底上所沉积多层膜中的 压应力值要小于BK7玻璃基底上所沉积多层膜中的压应力值. 用x射线衍射技术测量分析了膜 厚组合周期数不同的ZrO₂／SiO₂多层膜微结构，发现随着周期数增 加，多层膜的结晶程 度增强. 同时多层膜的微结构应变表现出了与所测应力不一致的变化趋势，这主要是由多层 膜中，膜层界面之间复杂的相互作用引起的. 关键词： 2／SiO₂多层膜')" href="#">ZrO₂／SiO₂多层膜 残余应力 膜厚组合周期数     

Gax In1-xP缓冲层组分对InP自组装形貌影响的研究

应用缓冲层对自组装结构的作用能Er和自组装结构表面能E8 的协同作用分析了InP自组装结构在GaxIn1-xP缓冲层表面的形貌变化.计算发现缓冲层组分影响自组装结构的形貌.随着缓冲层与InP自组装结构之间应力的增加,InP岛倾向于拉长.理论计算还发现随着自组装结构体积的增大,自组装结构也随之拉长.而且缓冲层的参数决定了自组装结构最小能量状态时的体积大小.应用金属有机物化学气相沉积技术在GaAs衬底上生长了不同的InP/GaInP体系,并对实验得到的自组装体系形貌进行了分析.实验结果证实了以上的理论分析.     

埋置量子点应力分布的有限元分析

通过衬底材料和外延材料的交替生长方式制备出多层排列的自组装量子点超晶格结构.这些埋置量子点的应力/应变场影响着它们的光电性能、压电性能以及力学稳定性.基于各向异性弹性理论的有限元方法,研究了埋置金字塔形应变自组织Ge/Si半导体量子点的应力/应变分布以及流体静应变和双轴应变分布,并与非埋置量子点的应力/应变分布做了比较,指出了它们之间的异同以及覆盖层对量子点应力/应变分布的影响. 关键词： 量子点 应力分布 应变分布     

光子晶体带隙和缺陷的特性

基于平面波展开法,以介电常数分别为1F/m和13F/m的物质构成三角晶格二维光子晶体,改变空气孔半径r与晶格常数a之间的大小,数值模拟得到r=0.48a时形成最大完全带隙0.4298-0.5192Hz.移去中心圆柱形成缺陷,数值模拟得到不能形成完全带隙结构,研究结论为光子晶体器件的制作提供参考.     

对羟基苯甲酸丁酯在蓖麻油-水界面上自组装及其重构动力学研究

以循环伏安法研究了对羟基苯甲酸丁酯在蓖麻油-水界面上自组装膜生长动力学,在自组装初期苯环以卧式定向按指数生长规律形成Langmuir自组装膜,成膜速率常数为0.0216min-1,单分子扩散系数为1.14×10-6cm2/s.自组装后期,苯环的卧式定向转化为立式定向,遵从S形玻兹曼函数,转化速率常数为k=0.0143min-1.自组装膜在支持电解质中以指数函数形式进一步重构成为完整、稳定的有序膜,重构速率常数为k=0.0319(士0.0011)min-1.自组装膜修饰电极在较高扫速下符合理想电容器模型,而在较低扫速下受离子扩散影响.自组装膜修饰较大程度地提高了电极的双电层电容.     

受限壁的选择性对软受限下星形三嵌段共聚物形貌的影响

基于嵌段共聚物在软受限条件下能够自组装形成很多有序结构,在催化、电子器件、光学传感等领域有广泛的应用价值,目前只对线性三嵌段共聚物在软受限下的自组装形貌做了分析,对星形三嵌段共聚物在软受限下的自组装行为还未有一个统一的定论.在这项研究中,应用模拟退火来研究ABC星形三嵌段共聚物在软受限下的自组装行为,嵌段与溶剂没有选择性下(中性壁),通过调整三个嵌段(f_A、f_B和f_C)的体积分数来构建相图,我们的模拟预测了各种独特的自组装纳米结构,包括薄片+球形、圆柱状,穿孔层,薄片+圆柱体,核壳补丁.然后通过改变嵌段与溶剂的选择性预测了链长度比为1:x:1的共聚物粒子形貌.通过计算接触数、均方根末端距与平均链长的比值以及平均键长随x的变化,验证了形貌转变机制.     

一种在线测量微机械薄膜残余应力的新结构

提出了一种利用临界屈曲法在线测量微机械薄膜残余应力的新结构，并采用表面微加工技术制作了两种测试样品.搭建了在线观测实验装置来实时监控释放过程中结构出现的临界屈曲变形模态，由此判断出结构内部的应力状态，同时在测得临界刻蚀深度的情况下，采用有限元方法计算出残余应力大小.借助有限元方法，先研究了多个参数对临界屈曲应力的影响，然后利用这种新结构对薄膜残余应力进行了实际测量，所得结果与微旋转结构的应力测量结果基本吻合.分析及实验表明，新结构在测量薄膜残余应力方面有许多优点，具有较高的实用价值，不仅能满足大量程的应力检测要求，而且只用一个结构就可以同时测量压应力和拉应力，从而极大提高了器件版图空间的利用率.     

Dynamical system approach to phyllotaxis

This paper presents a bifurcation study of a model widely used to discuss phyllotactic patterns, i.e., leaf arrangements. Although stable patterns can be easily obtained by numerical simulations, a stability or bifurcation analysis is hindered by the fact that the model is defined by an algorithm and not a dynamical system, mainly because new active elements are added at each step, and thus the dimension of the "natural" phase space is not conserved. Here a construction is presented by which a well defined dynamical system can be obtained, and a bifurcation analysis can be carried out. Stable and unstable patterns are found by an analytical relation, in which the roles of different growth mechanisms determining the shape is clarified. Then bifurcations are studied, especially anomalous scenarios due to discontinuities embedded in the original model. Finally, an explicit formula for evaluation of the Jacobian, and thus the eigenvalues, is given. It is likely that problems of the above type often arise in biology, and especially in morphogenesis, where growing systems are modeled.     

Fabrication of multi-scale structures with multiple X-ray masks and synchrotron hard X-ray irradiations

Synchrotron hard X-ray irradiation can be utilized in lithography processes to manufacture precise structures. Due to the difficulty of precise X-ray mask fabrication in hard X-ray lithography, this X-ray process has been used mainly to fabricate precise microstructures. In this study, a technology is proposed for fabricating novel multi-scale patterns that include submicron-scale structures using hard X-rays. The required X-ray masks for submicron-sized patterning are fabricated by a simple UV lithography process and sidewall metal deposition. Above all, thanks to the high penetration capability of hard X-rays with sub-nanometer wavelengths, it is possible to employ multiple masks to fabricate a variety of patterns. By combining each sub-micron X-ray mask with typical micro-sized X-ray masks, a unique X-ray lithography is performed, and various multi-scale structures are fabricated. The usefulness of the proposed technology is demonstrated by the realization of these structures.     

准自由支撑铝薄膜中有序表面结构的自组织生长

利用真空热蒸发方法在液体基底表面成功制备出具有自由支撑边界条件的金属铝薄膜系统，研究了薄膜中自发形成的自边界向内部区域逐渐生长而呈带状分布的有序表面结构.该有序结构的形成与薄膜厚度、沉积速率和真空环境中的生长时间等实验参数密切相关，其形成过程可用一个三阶段生长模型来描述.实验证明此类有序结构是在薄膜内应力作用下，铝原子及原子团簇在液体表面自由扩散凝聚所致.进一步的理论研究表明：基于特征的边界条件和固液相互作用，该自由支撑铝薄膜系统中包含了丰富的正弦形内应力分布，各种具有不同振幅和频率的正弦形内应力的合成可形成矩形状畴块和带状有序结构. 关键词： 液体基底 铝薄膜 自组织生长 有序结构     

Fabrication of patterned gold microstructure by selective electroless plating

Patterned gold microstructures on glass or Si wafers have been fabricated by a novel method which is composed of selective electroless plating and microcontact printing. This process may be widely used for the production of fine metal patterns in printed circuits or as a substrate to form patterned SAMs. In addition, these patterned metal microstructures can be readily transferred to adhesive tape surface to fabricate flexible metal microstructure, which may be applied in all-plastic circuit.     

Contribution of surface tension energy during plastic deformation of nanomaterials

The surface tension energy of crystallites in polycrystalline materials having different microstructures and in nanomaterials has been estimated. A hypothesis is proposed, according to which the yield stress of materials is determined by the balance of elastic energy and the surface tension energy of crystallites. The independently measured value of surface energy can be used to estimate the yield stress of polycrystalline materials.     

Biaxial stresses, surface roughness and microstructure in evaporated TiO2 films with different deposition geometries

The residual stresses, surface roughness and microstructure in titanium oxide films prepared by electron-beam evaporation and deposited with different geometries were investigated, with particular focus on the in-plane anisotropy of the biaxial stresses and microstructures. Thin films were deposited with various deposition angles on B270 glass substrates and silicon wafers. Two different types of deposition geometries were studied. The residual stress in the thin films was examined by a phase-shifting Twyman-Green interferometer. The optical constants, biaxial stress and surface roughness were found to be related to the evolution of the anisotropic microstructures in the films. The results revealed that the anisotropic stresses that developed in the evaporated titanium oxide films were dependent upon the deposition geometry and microstructure of the films.     

Anisotropic rheology during grain boundary diffusion creep and its relation to grain rotation,grain boundary sliding and superplasticity

The response of periodic microstructures to deformation can be analysed rigorously and this provides guidance in understanding more complex microstructures. When deforming by diffusion creep accompanied by sliding, irregular hexagons are shown to be anisotropic in their rheology. Analytic solutions are derived in which grain rotation is a key aspect of the deformation. If grain boundaries cannot support shear stress, the polycrystal viscosity is extremely anisotropic. There are two orthogonal directions of zero strength: sliding and rotation cooperate to allow strain parallel to these directions to be accomplished without any dissolution or plating. When a linear velocity/shear stress relationship is introduced for grain boundaries, the anisotropy is less extreme, but two weak directions still exist along which polycrystal strength is controlled only by the grain boundary “viscosity”. Irregular hexagons are characterised by four parameters. A particular subset of hexagons defined by two parameters, which includes regular hexagons as well as some elongate shapes, shows singular behaviour. Grain shapes that are close to that of the subset may exhibit large grain rotation rates and have no well-defined rheology unless there is a finite grain boundary viscosity. This new analysis explains why microstructures based on irregular but near equiaxed grains show high rotation rates during diffusion creep and it provides a framework for understanding strength anisotropy during diffusion creep.     

Superlattice Patterns in Coupled Turing Systems

In this paper, superlattice patterns have been investigated by using a two linearly coupled Brusselator model. It is found that superlattice patterns can only be induced in the sub-system with the short wavelength. Three different coupling methods have been used in order to investigate the mode interaction between the two Turing modes. It is proved in the simulations that interaction between activators in the two sub-systems leads to spontaneous formation of black eye pattern and/or white eye patterns while interaction between inhibitors leads to spontaneous formation of super-hexagonal pattern. It is also demonstrated that the same symmetries of the two modes and suitable wavelength ratio of the two modes should also be satisfied to form superlattice patterns.     

Strength of alloys with heterogeneous microstructures

The strengthening mechanisms of alloys composed of more than one phase are discussed in a systematic manner. A definition is proposed for certain types of microstructures. Plastic strain of fine dispersion structures (precipitation-hardened alloys) can vary between homogeneous and extremely localized in a few slip bands. There are consequences of localization on yield and fracture stress, static and cyclic work-hardening ability, fatigue crack initiation, and propagation.A distinction is required between fine and coarse two-phase structures. While the strength of the former can be adequately treated with dislocation theory, the latter require a micromechanical approach similar to that of composite materials. As examples will serve some aspects of strength of alloys with dual phase and duplex structures. Finally, it is shown that the microstructure leading to maximum yield stress need not be identical with that of optimum wear resistance.