纳米材料与微型机器外文文献翻译、中英文翻译

外文资料

Nanotechnology and Micro-machine

原文(一):

Nanomaterial

Nanomaterials and nanotechnology have become a magic word in modern society.

Nanomaterials represent today’s cutting edge in the development of novel advanced materials which promise tailor-made functionality and unheard applications in all key technologies. So nanomaterials are considered as a great potential in the 21th century because of their special properties in many fields such as optics, electronics, magnetics, mechanics, and chemistry. These unique properties are attractive for various high performance applications. Examples include wear resistant surfaces, low temperature sinterable high-strength ceramics, and magnetic nanocomposites. Nanostructures materials present great promises and opportunities for a new generation of materials with improved and marvelous properties.

It is appropriate to begin with a brief introduction to the history of the subject. Nanomaterials are found in both biological systems and man-made structures. Nature has been using nanomaterials for millions of years,as Disckson has noted: “Life itself could be regarded as a nanophase system”.Examples in which nanostructured elements play a vital role are magnetotactic bacteria, ferritin, and molluscan teeth. Several species of aquatic bacteria use the earth’s magnetic field to orient thenselves. They are able to do this because they contain chains of nanosized, single-domain magnetite particles. Because they have established their orientation, they are able to swim down to nutriments and away from what is lethal to them ,oxygen. Another example of nanomaterials in nature is that herbivorous mollusks use teeth attached to a tonguelike organ, the radula, to scrape their food. These teeth have a complex

structure containing nanocrystalline needles. We can utilize biological templates for

making nanomaterials. Apoferritin has been used as a confined reaction environment

for the synthesis of nanosized magnetite particles. Some scholars consider biological

nanomaterials as model systems for developing technologically useful nanomaterials.

Scientific work on this subject can be traced back over 100 years.In 1861 the

British chemist Thomas Graham coined the term colloid to describe a solution

containing 1 to 100 nm diameter particles in suspension. Around the turn of the

century, such famous scientists as Rayleigh, Maxwell, and Einstein studied colloids.

In 1930 the Langmuir-Blodgett method for developing monolayer films was

developed. By 1960 Uyeda had used electron microscopy and diffraction to study

individual particles. At about the same time, arc, plasma, and chemical flame furnaces

were employed to prouduce submicron particles. Magnetic alloy particles for use in

magnetic tapes were produced in 1970.By 1980, studies were made on clusters

containing fewer than 100 atoms .In 1985, a team led by Smalley and Kroto found

C clusters were unusually stable. In 1991, Lijima spectroscopic evidence that 60

reported studies of graphitic carbon tube filaments.

Research on nanomaterials has been stimulated by their technological

applications. The first technological uses of these materials were as catalysts and

pigments. The large surface area to volume ratio increases the chemical

activity.Because of this increased activity, there are significant cost advantages in

fabricating catalysts from nanomaterials. The peoperties of some single-phase

materials can be improved by preparing them as nanostructures. For example, the

sintering temperature can be decreased and the plasticity increased on single-phase,

structural ceramics by reducing the grain size to several nanometers. Multiphase

nanostructured materials have displayed novel behavior resulting from the small size

of he individual phases.

Technologically useful properties of nanomaterials are not limited to their

structural, chemical, or mechanical behavior. Multilayers represent examples of

materials in which one can modify of tune a property for a specific application by

sensitively controlling the individual layer thickness. It was discovered that the resistance of Fe-Cr multilayered thin films exhibited large changes in an applied magnetic field of several tens of kOe.This effect was given the name giant magnetoresistance (GMR). More recently, suitably annealed magnetic multilayers have been developed that exhibit significant magnetoresistance effects even in fields as low as 5 to10 Oe (Oersted). This effect may prove to be of great technological importance for use in magnetic recording read heads.

In microelectronics, the need for faster switching times and ever larger integration has motivated considerable effort to reduce the size of electronic components. Increasing the component density increases the difficulty of satisfying cooling requirements and reduces the allowable amount of energy released on switching between states. It would be ideal if the switching occurred with the motion of a single electron. One kind of single-electron device is based on the change in the Coulombic energy when an electron is added or removed from a particle. For a nanoparticle this enery change can be large enough that adding a single electron will effectively blocks the flow of other electrons. The use of Coulombic repulsion in this way is called Coulomb blockade.

In addition to technology, nanomaterials are also interesting systems for basic scientific investigations .For example, small particles display deviations from bulk solid behavior such as reductios in the melting temperature and changes (usually reductions) in the lattice parameter. The changes n the lattice parameter observed for metal and semiconductor particles result from the effect of the surface free energy. Both the surface stress and surface free energy are caused by the reduced coordination of the surface atoms. By studying the size dependence of the properties of particles, it is possible to find the critical length scales at which particles behave essentially as bulk matter. Generally, the physical properties of a nanoparticle approach bulk values for particles containing more than a few hundred atoms.

New techniques have been developed recently that have permitted researchers to produce larger quantities of other nanomaterials and to better characterize these materials.Each fabrication technique has its own set of advantages and

disadvantages.Generally it is best to produce nanoparticles with a narrow size distribution. In this regard, free jet expansion techniques permit the study of very small clusters, all containing the same number of atoms. It has the disadvantage of only producing a limited quantity of material.Another approach involves the production of pellets of nanostructured materials by first nucleating and growing nanoparticles in a supersaturated vapor and then using a cold finger to collect the nanoparticle. The nanoparticles are then consolidated under vacuum. Chemical techniques are very versatile in that they can be applied to nearly all materials (ceramics, semiconductors, and metals) and can usually produce a large amount of material. A difficulty with chemical processing is the need to find the proper chemical reactions and processing conditions for each material. Mechanical attrition, which can also produce a large amount of material, often makes less pure material. One problem common to all of these techniques is that nanoparticles often form micron-sized agglomerates. If this occurs, the properties of the material may be determined by the size of the agglomerate and not the size of the individual nanoparticles. For example, the size of the agglomerates may determine the void size in the consolidated nanostructured material.

The ability to characterize nanomaterials has been increased greatly by the invention of the scanning tunneling microscope (STM) and other proximal probes such as the atomic force microscope (AFM), the magnetic force microscope, and the optical near-field microscope.SMT has been used to carefully place atoms on surfaces to write bits using a small number of atmos. It has also been employed to construct a circular arrangement of metal atoms on an insulating surface. Since electrons are confined to the circular path of metal atoms, it serves ad a quantum ‘corral’of atoms. This quantum corral was employed to measure the local electronic density of states of these circular metallic arrangements. By doing this, researchers were able to verify the quantum mechanical description of electrons confined in this way.

Other new instruments and improvements of existing instruments are increasingly becoming important tools for characterizing surfaces of films, biological materials, and nanomaterials.The development of nanoindentors and the improved

ability to interpret results from nanoindentation measurements have increased our ability to study the mechanical properties of nanostructured materials. Improved high-resolution electron microscopes and modeling of the electron microscope images have improved our knowledges of the structure of the the particles and the interphase region between particles in consolidated nanomaterials.

Nanotechnology

1. Introduction

What id nanotechnology? it is a term that entered into the general vocabulary only in the late 1970’s,mainly to describe the metrology associated with the development of X-ray,optical and other very precise components.We defined nanotechnology as the technology where dimensions and tolerances in the range 0.1～100nm(from the size of the atom to the wavelength of light) play a critical role.

This definition is too all-embracing to be of practical value because it could include,for example,topics as diverse as X-ray crystallography ,atomic physics and indeed the whole of chemistry.So the field covered by nanotechnology is later narrowed down to manipulation and machining within the defined dimensional range(from 0.1nm to 100nm) by technological means,as opposed to those used by the craftsman,and thus excludes,for example,traditional forms of glass polishing.The technology relating to fine powders also comes under the general heading of nanotechnology,but we exclude observational techniques such as microscopy and various forms of surface analysis.

Nanotechnology is an ‘enabling’ technology, in that it provides the basis for other technological developments,and it is also a ‘horizontal’or ‘cross-sectional’technology in that one technological may,with slight variations,be applicable in widely differing fields. A good example of this is thin-film technology,which is fundamental to electronics and optics.A wide range of materials are employed in devices such as computer and home entertainment peripherals, including magnetic disc reading heads,video cassette recorder spindles, optical disc stampers and ink jet nozzles.Optical and semiconductor components include laser gyroscope mirrors,diffraction gratings,X-ray optics,quantum-well devices.

2. Materials technology

The wide scope of nanotechnology is demonstrated in the materials field,where materials provide a means to an end and are not an end in themseleves. For example, in electronics,inhomogeneities in materials,on a very fine scale, set a limit to the nanometre-sized features that play an important part in semiconductor technology, and in a very different field, the finer the grain size of an adhesive, the thinner will be the adhesive layer, and the higher will be the bond strength.

(1) Advantages of ultra-fine powders. In general, the mechanical, thermal, electrical and magnetic properties of ceramics, sintered metals and composites are often enhanced by reducing the grain or fiber size in the starting materials. Other properties such as strength, the ductile-brittle transition, transparency, dielectric coefficient and permeability can be enhanced either by the direct influence of an ultra-fine microstructure or by the advantages gained by mixing and bonding ultra-fine powders.

Oter important advantages of fine powders are that when they are used in the manufacture of ceramics and sintered metals, their green (i.e, unfired) density can be greatly increased. As a consequence, both the defects in the final produce and the shrinkage on firing are reduced, thus minimizing the need for subsequent processing.

(2)Applications of ultra-fine powders.Important applications include:

Thin films and coatings----the smaller the particle size, the thinner the coating can be

Electronic ceramics ----reduction in grain size results in reduced dielectric thickness

Strength-bearing ceramics----strength increases with decreasing grain size

Cutting tools----smaller grain size results in a finer cutting edge, which can enhance the surface finish

Impact resistance----finer microstructure increases the toughness of high-temperature steels

Cements----finer grain size yields better homogeneity and density

Gas sensors----finer grain size gives increased sensitivity

Adhesives----finer grain size gives thinner adhesive layer and higher bond strength

3. Precision machining and materials processing

A considerable overlap is emerging in the manufacturing methods employed in very different areas such as mechanical engineering, optics and electronics. Precision machining encompasses not only the traditional techniques such as turning, grinding, lapping and polishing refined to the nanometre level of precision, but also the application of ‘particle’ beams, ions, electrons and X-rays. Ion beams are capable of machining virtually any material and the most frequent applications of electrons and X-rays are found in the machining or modification of resist materials for lithographic purposes. The interaction of the beams with the resist material induces structural changes such as polymerization that alter the solubility of the irradiated areas.

(1) Techniques

1) Diamond turning. The large optics diamond-turning machine at the Lawrence Livermore National Laboratory represents a pinnacle of achievement in the field of ultra-precision machine tool engineering. This is a vertical-spindle machine with a face plate 1.6 m in diameter and a maximum tool height of 0.5m. Despite these large dimensions, machining accuracy for form is 27.5nm RMS and a surface roughness of 3nm is achievable, but is dependent both on the specimen material and cutting tool.

(2) Grinding

Fixed Abrasive Grinding The term“fixed abrasive” denotes that a grinding wheel is employed in which the abrasive particles, such as diamond, cubic boron nitride or silicon carbide, are attached to the wheel by embedding them in a resin or a metal. The forces generated in grinding are higher than in diamond turning and usually machine tools are tailored for one or the other process. Some Japanese work is in the vanguard of precision grinding, and surface finishes of 2nm (peak-to-valley) have been obtained on single-crystal quartz samples using extremely stiff grinding machines

Loose Abrasive Grinding The most familiar loose abrasive grinding processes are lapping and polishing where the workpiece, which is often a hard material such as

glass, is rubbed against a softer material, the lap or polisher, with abrasive slurry between the two surfaces. In many cases, the polishing process occurs as a result of the combined effects of mechanical and chemical interaction between the workpiece, slurry and polished.

Loose abrasive grinding techniques can under appropriate conditions produce unrivalled accuracy both in form and surface finish when the workpiece is flat or spherical. Surface figures to a few nm and surface finishes bettering than 0.5nm may be achieved. The abrasive is in slurry and is directed locally towards the workpiece by the action of a non-contacting polyurethane ball spinning at high speed, and which replac es the cutting tool in the machine. This technique has been named “elastic emission machining” and has been used to good effect in the manufacture of an X-ray mirror having a figure accuracy of 10nm and a surface roughness of 0.5nm RMS.

3）Thin-film production. The production of thin solid films, particularly for coating optical components, provides a good example of traditional nanotechnology. There is a long history of coating by chemical methods, electro-deposition, diode sputtering and vacuum evaporation, while triode and magnetron sputtering and ion-beam deposition are more recent in their wide application.

Because of their importance in the production of semiconductor devices, epitaxial growth techniques are worth a special mention. Epitaxy is the growth of a thin crystalline layer on a single-crystal substrate, where the atoms in the growing layer mimic the disposition of the atoms in the substrate.

The two main classes of epitaxy that have ben reviewed by Stringfellow (1982) are liquid-phase and vapour-phase epitaxy. The latter class includes molecular-beam epitaxy (MBE), which in essence, is highly controlled evaporation in ultra high vacuum. MBE may be used to grow high quality layered structures of semiconductors with mono-layer precision, and it is possible to exercise independent control over both the semiconductor band gap, by controlling the composition, and also the doping level. Pattern growth is possible through masks and on areas defined by electron-beam writing.

4. Applications

There is an all-pervading trend to higher precision and miniaturization, and to illustrate this a few applications will be briefly referred to in the fields of mechanical engineering,optics and electronics. It should be noted however, that the distinction between mechanical engineering and optics is becoming blurred, now that machine tools such as precision grinding machines and diamond-turning lathes are being used to produce optical components, often by personnel with a backgroud in mechanical engineering rather than optics. By a similar token mechanical engineering is also beginning to encroach on electronics particularly in the preparation of semiconductor substrates.

(1) Mechanical engineering

One of the earliest applications of diamond turning was the machining of aluminum substrates for computer memory discs, and accuracies are continuously being enhanced in order to improve storage capacity: surface finishes of 3nm are now being achieved. In the related technologies of optical data storage and retrieval, the toler ances of the critical dimensions of the disc and reading head are about 0.25 μm. The tolerances of the component parts of the machine tools used in their manufacture, i.e.the slideways and bearings, fall well within the nanotechnology range.

Some precision components falling in the manufacturing tolerance band of 5～50nm include gauge blocks, diamond indenter tips, microtome blades, Winchester disc reading heads and ultra precision XY tables (Taniguchi 1986). Examples of precision cylindrical components in two very different fields, and which are made to tolerances of about 100 nm, are bearing for mechanical gyroscopes and spindles for video cassette recorders.

The theoretical concept that brittle materials may be machined in a ductile mode has been known for some time. If this concept can be applied in practice it would be of significant practical importance because it would enable materials such as ceramics, glasses and silicon to be machined with minimal sub-surface damage, and could eliminate or substantially reduce the need for lapping and polishing.

Typically, the conditions for ductile-mode machining require that the depth of cut

is about 100 nm and that the normal force should fall in the range of 0.1～0.01N. These machining conditons can be realized only with extremely precise and stiff machine tools, such as the one described by Yoshioka et al (1985), and with which quartz has been ground to a surface roughness of 2 nm peak-to-valley. The significance of this experimental result is that it points the way to the direct grinding of optical components to an optical finish. The principle can be extended to other materials of significant commercial importance, such as ceramic turbine blades, which at present must be subjected to tedious surface finishing procedures to remove the structure-weakening cracks produced by the conventional grinding process.

(2) Optics

In some areas in optics manufacture there is a clear distinction between the technological approach and the traditional craftsman’s approach, particul arly where precision machine tools are employed. On the other hand, in lapping and polishing, there is a large grey area where the two approaches overlap. The large demand for infrared optics from the 1970s onwards could not be met by the traditional suppliers, and provided a stimulus for the development and application of diamond-turning machines to optic manufacture. The technology has now progressed and the surface figure and finishes that can be obtained span a substantial proportion of the nanotechnology range. Important applications of diamond-turned optics are in the manufacture of unconventionally shaped optics, for example axicons and more generelly, aspherics and particularly off-axis components. Such as paraboloids.

The mass production(several million per annum) of the miniature aspheric lenses used in compact disc players and the associated lens moulds provides a good example of the merging of optics and precision engineering. The form accuracy must be better than 0.2μm and the surface roughness m ust be below 20 nm to meet the criterion for diffraction limited performance.

(3) Electronics

In semiconductors, nanotechnology has long been a feature in the development of layers parallel to the substrate and in the substrate surface itself, and the need for precision is steadily increasing with the advent of layered semiconductor structures.

About one quarter of the entire semiconductor physics community is now engaged in studying aspects of these structures. Normal to the layer surface, the structure is produced by lithography, and for research purposes ar least, nanometre-sized features are now being developed using X-ray and electron and ion-beam techniques.

5. A look into the future

With a little imagination, it is not difficult to conjure up visions of future developments in high technology, in whatever direction one cares to look. The following two examples illustrate how advances may take place both by novel applications and refinements of old technologies and by development of new ones.

(1) Molecular electronics

Lithography and thin-film technology are the key technologies that have made possible the continuing and relentless reduction in the size of integrated circuits, to increase both packing density and operational speed. Miniaturization has been achieved by engineering downwards from the macro to the micro scale. By simple extrapolation it will take approximately two decades for electronic switches to be reduced to molecular dimensions. The impact of molecular biology and genetic engineering has thus provided a stimulus to attempt to engineer upwards, starting with the concept that single molecules, each acting as an electronic device in their own right, might be assembled using biotechnology, to form molecular electronic devices or even biochip computers.

Advances in molecular electronics by downward engineering from the macro to the micro scale are taking place over a wide front. One fruitful approach is by way of the Langmure-Biodgett (LB) film using a method first described by Blodgett (1935).

A multi-layer L

B structure consists of a sequence of organic monolayers made by repeatedly dipping a substrate into a trough containing the monolayer floating on a liquid (usually water), one layer being added at a time. The classical film forming materials were the fatty acids such as stearic acid and their salts. The late 1950s saw the first widespread and commercially important application of LB films in the field of X-ray spectroscopy (e.g, Henke 1964, 1965). The important properties of the films that were exploited in this application were the uniform thickness of each film, i.e.

one molecule thick, and the range of thickness, say from 5to 15nm, which were available by changing the composition of the film material. Stacks of fifty or more films were formed on plane of curved substrates to form two-dimensional diffraction gratings for measuring the characteristic X-ray wavelengths of the elements of low atomic number for analytical purposes in instruments such as the electron probe of X-ray micro-analyzer.

(2) Scanning tunneling engineering

It was stated that observational techniques such as microscopy do mot, at least for the purposes of this article, fall within the domain of nanotechnology. However,it is now becoming apparent that scanning tunneling microscopy(STM) may provide the basis of a new technology, which we shall call scanning tunneling engineering.

In the STM, a sharp stylus is positioned within a nanometre of the surface of the sample under investigation. A small voltage applied between the sample and the stylus will cause a current to foow through the thin intervening insulating medium (e.g.air, vacum, oxide layer). This is the tunneling electron current which is exponentially dependent on the sample-tip gap. If the sample is scanned in a planr parallel to ies surface and if the tunneling current is kept cnstant by adjusting the height of the stylus to maintain a constant gap, then the displacement of the stylus provides an accurate representation of the surface topographyu of the sample. It is relevant to the applications that will be discussed that individual atoms are easily resolved by the STM, that the stylus tip may be as small as a single atom and that the tip can be positioned with sub-atomic dimensional accuracy with the aid of a piezoelectric transducer.

The STM tip has demonstrated its ability to draw fine lines, which exhibit nanometre-sized struture, and hence may provide a new tool for nanometre lithography.The mode of action was not properly understood,but it was suspected that under the influence of the tip a conducting carbon line had been drawn as the result of polymerizing a hydrocarbon film, the process being assisted by the catalytic activity of the tungsten tip. By extrapolating their results the authors believed that it would be possible to deposit fine conducting lines on an insulating film. The tip would operate

in a gaseous environment that contained the metal atoms in such a form that they could either be pre-adsorbed on the film or then be liberated from their ligands or they would form free radicals at the location of the tip and be transferred to the film by appropriate adjustment of the tip voltage.

Feynman proposed that machine tools be used to make smaller machine tools which in turn would make still smaller ones, and so on all the way down to the atomic level. These machine tools would then operate via computer control in the nanometre domain, using high resolution electron microscopy for observation and control. STM technology has short-cricuired this rather cumbrous concept,but the potential applications and benefits remain.

原文(二)

Micro-machine

1. Introduction

From the beginning, mankind seems instinctively to have desired large machines and small machines. That is, “large” and “small” in comp arison with human-scale. Machines larger than human are powerful allies in the battle against the fury of nature; smaller machines are loyal partners that do whatever they are told.

If we compare the facility and technology of manufacturing larger machines, common sense tells us that the smaller machines are easier to make. Nevertheless, throughout the history of technology, larger machines have always stood ort. The size of the restored models of the water-mill invented by Vitruvius in the Roman Era, the windmill of the middle Ages, and the steam engine invented by Watt is overwhelming. On the other hand, smaller machined in history of technology are mostly tools. If smaller machines are easier to make, a variety of such machined should exist, but until modern times, no significant small machines existed except for guns and clocks.

This fact may imply that smaller machines were actually more difficult to make. Of course, this does not mean simply that it was difficult to make a small machine; it means that it was difficult to invent a small machine that would be significant to human beings.

Some people might say that mankind may not have wanted smaller machines. This theory, however, does not explain the recent popularity of palm-size mechatronics products.

The absence of small machines in history may be due to the extreme difficulty in manufacturing small precision parts.

2. Why Micro-machine Now

The dream of the ultimate small machine, or micro-machine, was first depicted in detail about 30 years ago in the 1966 movie “Fantastic V oyage”.At the time the study of micro machining of semiconductors had already begun. Therefore, manufacturing minute mechanisms through micro machining of semiconductors would have been possible, even at that time.There was, however, a wait of over 20 years before the introduction, about 10 years ago, of electrostatic motors and gears made by semiconductor micro machining.

Why didn’t the study of micro machining and the dream of micro- machines meet earlier? A possible reason for this is as follows. In addition to micro machining, the development of micro-machines requires a number of technologies including materials, instrumentation, control, energy, information processing, and design. Before micro-machine research and development can be started, all of these technologies must reach a certain level. In other words, the overall technological level, as a whole, must reach a certain critical point, but it hadn’t reached that point 30 years ago.

Approximately 20 years after “Fantastic V oyage,” the technology level for micro-machines finally reached a critical point. Micromotors and microgears made by semiconductor micromachining were introduced at about that time, triggering the research and development of micro- machines.

The backgroud of the micro-machine boom, which started about 10 years ago, can be explained by the above.

3. Micro-machine as Gentle Machines

How do micro-machines of the future differ from conventional machines? How will they change the relationship between nature and humans?

The most unique feature of a micro-machine is, of course, its small size. Utilizing its tiny dimensions, a micro-machine can perform tasks in a revolutionary way that would be impossible for conventional machines. That is, micro-machines do not affect the object or the environment as much as conventional machines do. Micro-machines perform their tasks gently. This is a fundamental difference between micro-machines and conventional machines.

The medical field holds the highest expectations for benefits from this feature of micro-machines.Diagnosis and treatment will change drastically from conventional methods, and “Fantastic V oyage”may no longer be a fantasy. If a micro-machine can gently enter a human body to treat illnesses, humans will be freed from painful surgery and uncomfortable gastro-camera testing. Furthermore, if micro-machines can halt the trend of ever-increasing size in medical equipment, it could slow the excess growth and complexity of medical technology, contributing to the solving of serious problems with high medical costs for citizens.

Micro-machines are gentle also in terms of machine maintenance, since they can be inspected and repaired without difficulty in reaching and overhauling the engine or plant. The more complex the machine, the more susceptible it is to malfunction due to overhaul and assembly. In addition, there have been more instances of human errors during overhaul and assembly. It is good for the machine id overhaul is not necessary.Itis even better if maintenance can be performed without stopping the machine. Repeated stop-and-go operation will accelerate damage of the machine due to excess stress caused by thermal expansion.

Such gentleness of a micro-machine id an advantage, as well as a weakness in that a micro-machine id too fragile to resist the object or the environment. This is the drawback of the micro-scale objects.

For example, a fish can swim freely against the current, but small plankton cannot. This is result of physical laws and nothing can change it. Still, the plankton can live and grow in the natural environment by conforming to the environment.

Unlike conventional machines which fight and control nature, micro-machines will probably adapt to and utilize nature. If a micro-machine cannot proceed against

the current, a way will be found to proceed with the flow, naturally avoiding collisions with obstacles.

4. Micro-electronics and Mechatronics

The concept of micro-machines and related technologies is still not adequately unified, as these are still at the development stage. The micro-machines and related technologies are currently referred to by a variety of different terms. In the United States, the accepted term is “Micro Electro Mechanical Systems” (MEMS); in Europe, the term “Microsystems Technology” (M ST) is common, while the term “micro-engineering” is sometimes used in Britain. Meanwhile in Australia “micro-machine”.The most common term if it is translated into English is “micro-machine”in Japan. However “micro-robot” and “micro-mechanism” are also available case by case.

The appearance of these various terms should be taken as reflecting not merely diversity of expression, but diversity of the items referred to. Depending on whether the item referred to is an object or a technology, the terminology may be summed up as follows:

Object: micro-robot, micro-mechanism

Technology: micro-engineering, MST

Object＆technology:MEMS, micro-machine

With regard to technology, if we summarize the terms according to 1) where the technology for micro-machine systems branched off from; and 2) whether the object dealt with by the technology in question is an element or a machine system, the terms can be organized as follows.That is, MEMS and MST stem from mechatronics, and have developed dealing mainly with machine systems. In this sense, MEMS and MST on the one hand and micro-machines and microengineering on the other hand form two separate groups, but as the former has started to move in the direction of machine systems, while the later has already incorporated microelectronics,the differences between the two groups are gradually disappearing.

Looking at the ares included in the two groups, given that the machine systems which are the main concern of micro-machines include elements, and given also that

micro-machines include microelectronics,it would be natural to assume that micro-machines include MEMS and MST.

中文翻译

纳米材料与微型机器

纳米材料

在现代社会中纳米材料和纳米技术已经成了神奇的词。

在新型先进材料的发展中，纳米材料代表今天的前沿，在所有的关键技术中，它预示着度身定造的功能和闻所未闻的应用。由于在许多领域纳米材料有其特殊的性质，（如光学，电子，磁学，力学，化学），因此人们认为在21世纪它有很大潜力。这些独特的性能吸引着各种各样高性能应用。例如拥有耐磨表面，低温高强度陶瓷，和磁性纳米复合材料。在拥有良好的令人惊奇的性质的新一代材料中，纳米结构材料呈现出很大的惊喜和机会。

我们适当的以简要介绍这个主题的历史为开始。在生物系统和人造结构中发现了纳米材料。数百万以来大自然一直在使用纳米材料，正如Disckson已指出：“生活本身可视为纳米系统” 。例如，在趋磁细菌，铁，和软体动物的牙齿中纳米分子发挥重要作用。数种水生细菌利用地球的磁场定位它们自己。他们能够做到这一点，因为它们含有纳米链，单域磁铁矿颗粒。因为它们建立了自己的方向，为了食物他们能游到海底远离致命的东西，氧气。纳米材料在自然界的另一个例子是草食性软体动物用牙附着于齿舌，获得他们的食物。这些牙齿有一个复杂的结构，含有纳米针头。我们可以利用生物模板制造纳米材料。为合成纳米磁铁矿颗粒,apoferritin已被用来作为一种局限于反应的环境。一些学者认为生物纳米材料作为发展在技术上有用的纳米材料的模型系统，。

科学工作就这个问题可以追溯到100多年前.在 1861年，英国化学家托马斯格雷厄姆在被停牌时创造了胶体名词来描述一个解决方案包含直径1至100纳米的颗粒。围绕世纪之交，一些著名科学家像瑞利，麦克斯韦，爱因斯坦都研究胶体。1930年开发单层薄膜的Langmuir - blodgett方法在发展。到1960年uyeda使用了电子显微镜和衍射研究个别粒子。与此同时，电弧，等离子，化学火焰炉都用于生产亚微米粒子。1970年磁性合金颗粒使用在磁带制作.到1980年，提出了含有少于100个原子集群的研究。在1985年，由Smalley 和kroto

C集群异常稳定。在1991年， lijima 所领导的设计小组发现光谱，证据表明，60

报道了石墨碳管细丝的研究。

他们的技术应用已刺激了纳米材料的研究。第一次技术利用这些材料作为催化剂和颜料。该大型区域表面的体积比率增加了化学反应.由于这一活动的增加，在制造纳米材料催化剂方面有显著的成本优势。一些单相材料的性能可以由准备像纳米结构来提高。举例来说，通过减少晶粒尺寸的几个毫微米，单相结构陶瓷的烧结温度降低和可塑性增加。多相纳米材料表现出新颖的行为造成单个时期的小规模。

在技术上有用的属性纳米材料不仅限于其结构，化学或机械行为。材料的多层代表例子之一是通过敏锐地控制个别层厚度来修改调节特殊应用软件的性能。人们发现铁铬多层薄膜的阻力应用磁场的数十koe展示出很大的变化.它的作用被命名为巨磁电阻（ GMR ）。最近，适当的退火磁性多层膜已发展，它展现出显著的磁电阻效应，甚至在像5 到10光电（ oersted ）的各个领域。这个效应可能会使用在磁记录读取头证明有很大的技术重要性。

在微电子领域，需要更快的开关时间和更大的一体化付出相当大的努力，以

减少电子零件的大小。组件密度的增长增加了满足冷却需求的困难，并减少在状

态下所允许的释放的大量能量之间的转换.如果一个单一电子切换发生，它将会

是理想的。一种单电子器件在库仑能源时电子从一个粒子添加或删除的基础上变

化。对于一个纳米粒子来说，这能量变化可以足够大，以至添加单电子将有效地

阻止流动的其他电子。库仑斥力以这种方式的使用是所谓的库仑封锁。

此外，对于技术来说，纳米材料也有有趣的系统为基本的科学调查。例如，

小的颗粒显示偏离散装固体的行为，如在晶格参数熔点减少和变化（通常是减

少）。晶格参数的变化遵守金属和半导体粒子由表面应力效果引起的结果。同时

表面自由能造成熔点的降低。表面原子的协调减少造成了表面应力和表面自由

能。通过研究依赖性质的粒子的大小，有可能找到关键长度尺度像大批物质粒子

的行为。一般来说，纳米粒子的物理性能有很多价值因为颗粒含有超过数百原子。

新技术已经开发，最近已批准研究人员生产大数量的其他纳米材料和更好地

表征这些材料.每个制作技术都有自己的优势和缺点.一般地，最好是生产有一个

狭窄大小分布的纳米粒子。在这方面，自由射流扩展技术允许研究非常小的集群，

所有的都含有相同数目的原子。它有只生产数量有限的材料的缺点.另一种做法，涉及生产微丸的纳米材料，首先是在过饱和蒸汽下的核和日益增长的纳米粒子然后在综合真空条件下用冷指针收集纳米粒子。化学技术是非常灵活的，因为它们可以适用于几乎所有的材料（陶瓷，半导体，金属），并通常可以生产大量的材料。化学加工的困难，是要为每一种材料找到适当的化学反应和加工条件。技工减员，往往使用少纯的物质也可以生产出大量的材料。所有这些技术的一个共同问题是纳米粒子的形式往往是微米大小。如果发生这种情况，材料的性能可能由团聚的大小确定，而不是单个纳米粒子的大小。例如在加固的纳米材料中，大小的团聚体可决定无效的大小。

表征纳米材料的能力已大大增加通过发明的扫描隧道显微镜（ STM ）和其他近端探针如原子力显微镜（ AFM ），磁力显微镜和光学近场显微镜. STM已用来仔细在表面定位原子以使用一个少量原子写字。它也已用于金属原子在绝缘的表面构造环形。由于电子限于金属原子的环形内，它作为原子的量子围栏存在。这量子围栏被用来衡量当地的这些金属安排的电子态密度的通告。这样做的话，研究员能够以这种方式验证量子力学描述电子局限。

其他新的手段和现有工具的改善正日益成为描述表面薄膜，生物材料和纳米材料的重要的工具。从纳米订货方法造成的纳米订货商发展和解释能力的提高，已经增加了我们研究纳米材料机械性能的能力。改进的高分辨电子显微镜和电子显微镜图像建模已经提高了我们在综合纳米材料中粒子和界面区域之间结构的知识。

纳米技术

1.简介

什么是纳米科技？在20世纪70年代末的时候这是一个进入普通词汇的名词，主要是来形容计量与X射线的发展，光学和其他非常精确的组件. 我们把纳米技术定义为一种技术，尺寸和公差范围在0.1 ? 100 nm（从原子的大小到光的波长）发挥关键的作用。

这个定义是包含实用价值，因为它可包括，例如，主题不同的X射线晶体学，原子物理学乃至整个的化学.因此领域所涵盖的纳米科技是后来缩小操控和加工内部定义的三维范围（从0.1nm到100 nm的）的技术手段，技工反对那些用途，从而排除了，例如传统形式的玻璃磨光技术.这种技术与精细粉末有关，它也来

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