“看见”一种新型的二维冰结构

 固体表面与水(冰)形成的界面是自然界中最常见的界面之一。它直接或者间接地影响到我们的日常生活以及工业技术的方方面面,对于该问题的科学研究涉及表面物理、大气化学、环境科学等多个领域。其中,水在固体表面发生的多相结晶过程是人们研究水和固体界面的一个重要方面。在地上,这种结冰过程能形成美丽的冰川,也会导致路面和铁轨结冰而阻碍交通;在空中,这种结冰过程是大气层循环中的一个重要组成部分,同时也是很多起飞机事故的元凶。     

微观尺度下的水:从准一维、二维受限空间到生物以及材料表面

地球上的各种过程,包括物理、化学、环境和生物等,大多数与微观尺度下的界面水息息相关.界面水有大量悬而未决的基础科学问题,长期以来水都是重要的科学研究对象.本文通过从一维受限空间、二维表面以及生物大分子和材料表面上的水等角度概述当前的一些研究进展,讨论与界面水相关的一些前沿问题,以及在界面水方面的基础研究和新技术的突破对于解决这些前沿问题的必要性.     

超高时空分辨光电子显微镜的研究进展(特邀)

新型光电材料、磁性材料、低维量子材料等是目前凝聚态物理的研究前沿,其在微纳尺度的近场光学动力学具有丰富的物理内涵和广阔的应用前景。飞秒激光的超高时间分辨与光电子显微镜的超高空间分辨结合为一种超高时空分辨测量技术,为材料物理、表面物理等研究注入了新的活力,提供了强有力的平台。本文介绍了超高时空分辨光电子显微镜,讨论了其在金属表面等离激元动力学、低维材料等新型半导体材料动力学、材料异质结界面动力学等方面的应用和研究进展,最后展望了其在飞秒-纳米尺度表面和界面物理研究的应用前景。     

液晶界面物理效应研究及进展

液晶表面和与它接触的固体表面的相互作用，作为边界条件对液晶显示起着重要的控制作用，并影响着液晶表现出的各种物理效应．液晶表面和界面科学一直是液晶物理学研究的重要领域．这一领域内一个重要的课题是，从物理机理出发寻找正确反映界面作用规律的数学物理方程，以便完善发展液晶界面理论，指导界面诱导技术．文章就这一研究领域已取得的成果、未解决的问题、当前研究的热点(一级转变和挠曲电效应)及目前有争议的问题(表面弹性项是否存在等)进行了介绍。     

表面增强拉曼散射光谱的应用进展

表面增强拉曼光谱是一种非常有效的探测界面特性和分子间相互作用、表征表面分子吸附行为和分子结构的工具。已成为灵敏度最高的研究界面效应的技术之一,最大范围地应用于研究吸附分子在表面的取向及吸附行为、吸附界面表面状态、生物大分子的界面取向及构型、构象和结构分析;SERS技术也逐渐成为表面科学和电化学领域有力的研究手段,并已在痕量分析乃至单分子检测、化学及工业、环境科学、生物医学体系、纳米材料以及传感器等方面的研究中得到了广泛应用,甚至出现了拉曼技术与其他技术的联用。文章综述了近几年来表面增强拉曼散射作为一种光谱技术在这些应用领域的研究进展以及潜在应用价值;并简单介绍了作者所在实验室的相关工作,特别是富勒烯和碳纳米管材料等领域的一些探讨与研究。     

钙钛矿型铁电氧化物表面结构与功能的控制及其潜在应用

钙钛矿型铁电氧化物由于具有本征的、非易失的、可翻转的自发极化以及带有高电荷密度的极性表面等特性,被认为是最有前途的功能材料之一.研究钙钛矿型铁电氧化物的表面结构对理解其表面/界面能量转化、调控表面物质吸附和脱附、控制界面化学反应、以及设计稳定的低功耗电子器件具有重要意义.本文首先概述了铁电相与其表面结构的关系,并介绍了钙钛矿型铁电氧化物复杂表面结构的形成;之后阐述了铁电表面/界面结构的调控机制,为后续的钙钛矿型铁电氧化物的表面结构设计、表面性能与功能的控制提供了研究基础;最后介绍了铁电氧化物表面/界面的功能调控和潜在器件的设计,并结合目前铁电材料领域表面科学研究的局限性,对今后基于钙钛矿型铁电氧化物表面结构的研究发展以及应用前景提出了展望.     

Co/Cu(111)薄膜生长和退火过程中的扩散

利用同步辐射角分辨光电子能谱和俄歇电子能谱研究了CoCu(111)分子束外延薄膜在生长和退火过程中的电子结构.实验发现:随着Co膜厚度的增加,Cu的sdz2杂化带能级位移相应增大,证实了界面间发生了互混;退火过程中存在表面扩散,而非通过界面的体扩散.并把这两种不同过程的扩散的内在动力归结为Co的表面自由能显著大于Cu的表面自由能 关键词： 表面扩散和界面混合物形成 固体表面能 表面态和能带结构     

全固态电池中界面的结构演化和物质输运

全固态电池中科学问题的本质在于引入的固态电解质的特性及全新的固-固界面的存在.从构-效关系出发,固-固界面和电解质自身的结构演化与物质输运过程决定了全固态电池的性能.随着固态电解质材料研究的不断丰富,目前全固态电池中的问题主要集中在固-固界面,界面处的组成和结构限制了全固态电池的性能.根据固-固界面接触的情况不同,本文按照固-固界面物理接触、化学接触和表面改性处理这三个层次总结与讨论全固态电池中固-固界面处的结构及其物质输运.最后从功能材料功能性起源角度讨论局域对称性与宏观复杂体系下材料性能的关联.     

表面物理与表面物理国家重点实验室

 日常生活中人们无时无刻不在与表面打交道,人类对物质的认识也总是从表面开始才能够逐渐深入的。我们生活在地球表面,在板块运动以及空气和水的侵蚀作用下,地表形成复杂的山川河流,由此我们欣赏到迷人的自然风光。在较小的尺度下,各种植物的枝叶、果实在表面应力作用下呈现不同的形状,为我们识别、利用丰富的自然资源提供了特征依据。人们甚至通过对材料表面进行修饰,从而实现对其功能的设计和调控,比如在钢铁表面电镀惰性金属,可以大大提高钢铁结构的抗腐蚀能力和美观性;而通过对镜头表面镀膜厚度的控制,能够实现滤光或增透的目的。在肉眼不能直接观察的微观尺度上,表面上发生的众多物理、化学现象和过程,也在我们的生产生活中扮演着重要的角色,比如金属纳米颗粒对一些重要化学反应的催化作用,半导体界面对电子传输的调制作用等。正是表面科学帮助人们理解这些行为产生的微观机理,并帮助人们探索控制、优化材料相应功能的方法,从而推动人类文明社会的发展。     

仿生多尺度超浸润界面材料

仿生多尺度超浸润界面材料是20世纪90年代末以来迅速发展起来的一类新型功能材料,该研究领域突出的特点是基础研究和应用研究密切结合、仿生理念与材料制备技术密切结合.近年来,研究人员围绕仿生多尺度超浸润界面材料的构筑与应用中的若干关键科学问题开展了深入研究,取得了一系列有特色、有创新意义的研究成果,开发出了一系列的材料制备新方法和新技术.本文首先介绍仿生多尺度超浸润界面材料的发展历程和固体表面浸润性的理论基础;然后讨论对自然界中具有特殊浸润性能的功能表面的原理揭示和仿生设计;对仿生多尺度超浸润界面材料的典型应用领域,例如自清洁、集水、防冰、油水分离以及化学反应等进行了总结;最后对仿生多尺度超浸润界面材料的发展前景进行了讨论.     

Off-axis electron holography of hetero-interfaces

Off-axis electron holography is one of the new emerging methods for high spatial resolution characterization of interfaces in materials. It enables recording and retrieval of both amplitude and phase of an electron wavefunction scattered by a specimen. Phase changes introduced by magnetic and electrostatic fields have been studied in the first applications of electron holography to domain walls in ferromagnetic and ferroelectric materials and to p-n junctions. Planar defects in single crystals, such as stacking faults, have been observed with strong phase contrast due to dynamical diffraction.Applications to heterogeneous interfaces have only started. High phase contrast due to mean inner potential differences is found for interfaces between high and low atomic number materials. Dynamical contributions to the phase of the transmitted beam are important for epitaxial interfaces in strongly diffracting orientations. Numerical hologram reconstructions yield quantitative amplitude and phase images of an interface which are energy filtered and are in perfect registry. Both are function of specimen thickness. The thickness dependence can be eliminated by division of the phase image with a logarithm of the amplitude image. This ratio maps the product of the mean inner potential and the mean free path for inelastic scattering across a hetero-interface in weekly diffracting orientations.Resolution enhancement through aberration correction has not been demonstrated for interfaces as yet. Holography of interfaces in plan view is unexplored.     

Femtosecond laser ablation profile near an interface: Analysis based on the correlation with superficial properties of individual materials

Femtosecond laser ablation of materials is turning to be an important tool for micromachining as well as for selective removal of biological tissues. In a great number of applications, laser ablation has to process through interfaces separating media of different properties. The investigation of the ablation behavior within materials and passing through interfaces is the main aim of this study. Especially, the analysis of the discontinuity in the ablation profile close to interfaces between distinct materials can reveal some of the phenomena involved in the formation of an ablated microcavity geometry. We have used a method that correlates the ablation cross sectional area with the local laser intensity. The effective intensity ablation properties were obtained from surface ablation data of distinct materials. The application of this method allows the prediction of the occurrence of a size discontinuity in the ablation geometry at the interface of distinct media, a fact which becomes important when planning applications in different media.     

纳米多晶体的热力学函数及其在相变热力学中的应用

以往关于纳米材料热力学的研究，绝大多数以界面的热力学函数表征整体纳米材料的热力学性质，这种近似处理，对于尺寸超过几十纳米的较粗纳米材料，在相变热力学中对特征转变温度和临界尺寸等重要参量的预测，将导致很大误差. 应用“界面膨胀模型”和普适状态方程，研究了纳米晶界的热力学特性，进一步发展了纳米晶整体材料热力学函数的计算模型，给出了单相纳米多晶体的焓、熵和吉布斯自由能随界面过剩体积、温度，以及晶粒尺寸发生变化的明确表达式. 以Co纳米晶为例，分析了界面与整体纳米多晶体热力学函数的差异，确定了相变温度与晶粒尺寸的依赖关系，以及一定温度下可能发生相变的临界尺寸. 关键词： 纳米多晶体 热力学函数 相变热力学     

The growth and modification of materials via ion–surface processing

A wide variety of gas phase ions with kinetic energies from 1–10⁷ eV increasingly are being used for the growth and modification of state-of-the-art material interfaces. Ions can be used to deposit thin films; expose fresh interfaces by sputtering; grow mixed interface layers from ions, ambient neutrals, and/or surface atoms; modify the phases of interfaces; dope trace elements into interface regions; impart specific chemical functionalities to a surface; toughen materials; and create micron- and nanometer-scale interface structures. Several examples are developed which demonstrate the variety of technologically important interface modification that is possible with gas phase ions. These examples have been selected to demonstrate how the choice of the ion and its kinetic energy controls modification and deposition for several different materials. Examples are drawn from experiments, computer simulations, fundamental research, and active technological applications. Finally, a list of research areas is provided for which ion–surface modification promises considerable scientific and technological advances in the new millennium.     

用离子辐照模拟研究反应堆结构材料中金属/金属界面原子扩散行为

介绍了利用载能离子辐照模拟研究反应堆结构材料中金属／金属界面原子扩散行为的实验进展,特别是辐照参数（如辐照剂量、辐照温度、核能损、电子能损以及膜结构等）对界面原子扩散行为的影响,并对可能的机理进行了简要的评述。 Atom diffusion at metal/metal interfaces is very important for property of reactor structural materials, which can be simulated by using energetic ion irradiations. The present situation of experimental studies on atom diffusion at metal/metal interfaces induced by energetic ion irradiations is reviewed. The influence of experimental parameters such as the irradiation dose, irradiation temperature, electronic energy loss, nuclear energy loss and the interface structure on the intermixing is emphatically introduced. In addition, the possible mechanisms of metal/ metal intermixing are also briefly described.     

单负材料界面处反射相位特性研究

根据Maxwell电磁场理论,推导出线偏振单色平面波的普适菲涅尔表达式,得到特异材料反射相移计算公式。利用反射相移公式研究了线偏振单色平面波从空气入射到单负材料(ε0或μ0)时分界面处反射相位的特性。结果表明单负材料界面处反射相位连续变化,与传统材料全反射的相位变化特点相似。     

Design, synthesis and characterisation of interfaces in engineering materials

Examples of recent work where novel interfaces have been designed and synthesised in a variety of materials are presented. The significance of characterisation using transmission electron microscopy and atom probe field ion microscopy is emphasised as a key tool for providing feedback into the design and synthesis. This is particularly true for complex multicomponent materials such as discussed here, where the materials design is largely concerned with achieving the right blance of solute across specific interfaces. The discussion focuses on precipitate/matrix inter-faces in turbine rotor steels used for power generation and internal interfaces in precipitation in an experimental multi-component aluminium alloy.     

Elastic energy-driven phase separation of phospholipid monolayers at the nematic liquid-crystal-aqueous interface

Experimental measurements and a thermodynamic model reveal that nematic elasticity can induce lateral phase separation of amphiphilic molecules assembled at interfaces between thermotropic liquid crystals (LCs) and immiscible aqueous phases. The morphologies of the phase-separated domains of amphiphiles induced by nematic elasticity are shown to be strongly dependent on the nature of the deformation of the LC. This study provides important insight into the physics that controls the ordering of molecules at interfaces of soft anisotropic materials, and identifies a new mechanism of phase separation at these interfaces.     

Thermodynamics and structural aspects of grain boundary segregation

Physical and chemical properties of solid materials are strongly. influenced by the chemical composition of internal interfaces, One of the crucial parameters affecting interfacial chemistry is the atomic structure of the interface. Due to its importance. a considerable amount of work was done to elucidate the relationship between structure and chemical composition of interfaces. This article reviews the present understanding of an important and fundamental part of this relationship, namely, the structural aspects of grain boundary segregation. After a brief outline of grain boundary structure and geometry. thermodynamic approaches to describe grain boundary segregation are summarized and their application to materials is discussed. covering particular sites at a single grain boundary as well as the role of interfaces in polycrystals. Both the experimental evidence of grain boundary segregation anisotropy and the theoretical results of computer simulations of grain boundary segregation are summarized. Useful methods of predicting grain boundary segregation are presented. Finally, segregation behavior of solutes at grain boundaries is compared with that at free surfaces, and examples of chemical composition of intexphase boundaries are given.     

Orientation-dependent transparency of metallic interfaces

As devices are reduced in size, interfaces start to dominate electrical transport, making it essential to be able to describe reliably how they transmit and reflect electrons. For a number of nearly perfectly lattice-matched materials, we calculate from first principles the dependence of the interface transparency on the crystal orientation. Quite remarkably, the largest anisotropy is predicted for interfaces between the prototype free-electron materials silver and aluminum, for which a massive factor of 2 difference between (111) and (001) interfaces is found.