Modern materials science

In spite of the slow development of crystal structure analysis, once it did take olT it involved a huge number of investigators tens of thousands of crystal structures were determined, and as experimental and interpretational techniques became more sophisticated, the technique was extended to extremely complex biological molecules. The most notable early achievement was the structure analysis, in 1949, of crystalline penicillin by Dorothy Crowfoot-Hodgkin and Charles Bunn this analysis achieved something that traditional chemical examination had not been able to do. By this time, the crystal structure, and crystal chemistry, of a huge variety of inorganic compounds had been established, and that was most certainly a prerequisite for the creation of modern materials science. 

This chapter is entitled Precursors of Materials Science and the foregoing major Sections have focused on the atomic hypothesis, crystallography, phase equilibria and microstructure, which I have presented as the main supports that made possible the emergence of modern materials. science. In what follows, some other fields of study that made substantial contributions are more brielly discussed. It should be remembered that this is in no way a le.xihnok, my task is not to explain the detailed nature of various phenomena and entitities, but only to outline how they came to be invented or recognised and how they have contributed to the edifice of modern materials science. The reader may well think that I have paid too much attention, up to now, to metals that was inevitable, but I shall do my best to redress the balance in due course. 

The study of the multifarious magnetic properties of solids, followed in due course by the sophisticated control of those properties, has for a century been a central concern both of physicists and of materials scientists. The history of magnetism illustrates several features of modern materials science. 

The characterisation of materials is a central necessity of modern materials science. Effectively, it signifies making precise distinctions between different specimens of what is nominally the same material. The concept covers qualitative and quantitative analysis of chemical composition and its variation between phases the examination of the spatial distribution of grains, phases and of minor constituents the crystal structures present and the extent, nature and distribution of structural imperfections (including the stereological analysis outlined in Chapter 5). 

In this chapter, I propose to take a strongly historical approach to the field, and focus on just a few of the numerous techniques of investigation and characterisation . What is not in doubt is that these techniques, and the specialised research devoted to improving them in detail, are at the heart of modern materials science. 

The Stereoscan instruments were a triumphant success and their descendants, mostly made in Britain, France, Japan and the United States, have been sold in thousands over the years. They are indispensable components of modern materials science laboratories. Not only that, but they have uses which were not dreamt of when Oatley developed his first instruments thus, they are used today to image integrated microcircuits and to search for minute defects in them. 

Recent texts have assembled impressive information about the production, characterisation and properties of semiconductor devices, including integrated circuits, using not only silicon but also the various compound semiconductors such as GaAs which there is no room to detail here. The reader is referred to excellent treatments by Bachmann (1995), Jackson (1996) and particularly by Mahajan and Sree Harsha (1999). In particular, the considerable complexities of epitaxial growth techniques - a major parepisteme in modern materials science - are set out in Chapter 6 of Bachmann s book and in Chapter 6 of that by Mahajan and Sree Harsha. 

Ultramodern techniques are being applied to the study of corrosion thus a very recent initiative at Sandia Laboratories in America studied the corrosion of copper in air spiked with hydrogen sulphide by a form of combinatorial test, in which a protective coat of copper oxide was varied in thickness, and in parallel, the density of defects in the copper provoked by irradiation was also varied. Defects proved to be more influential than the thickness of the protective layer. This conclusion is valuable in preventing corrosion of copper conductors in advanced microcircuits. This set of experiments is typical of modern materials science, in that quite diverse themes... combinatorial methods, corrosion kinetics and irradiation damage... are simultaneously exploited. 

As we saw in Chapter 3, the founding text of modern materials science was Frederick Seitz s The Modern Theory of Solids (1940) an updated version of this, also very influential in its day, was Charles Wert and Robb Thomson s Physies of Solids (1964). Alan Cottrell s Theoretical Structural Metallurgy appeared in 1948 (see Chapter 5) although devoted to metals, this book was in many ways a true precursor of materials science texts. Richard Weiss brought out Solid State Physics for Metallurgists in 1963. Several books such as Properties of Matter (1970), by Mendoza and Flowers, were on the borders of physics and materials science. Another key precursor book, still cited today, was Darken and Gurry s book. Physical Chemistry of Metals (1953), followed by Swalin s Thermodynamics of Solids. 

In modern materials science topics of high interest are surface structures on small (nanometer-length) scales and phase transitions in adsorbed surface layers. Many interesting effects appear at low temperatures, where quantum effects are important, which have to be taken into account in theoretical analyses. In this review a progress report is given on the state of the art of (quantum) simulations of adsorbed molecular layers. 

Although typically whiggish, Smith s historical survey is extremely rich and useful because it emphasizes the interplay between various academic disciplines and the longstanding practical tradition of metallurgists. The quotation above points out at the two fundamental notions - structure and properties - of modem metallurgy which are also the basis of the conceptual framework of modern materials science. The earliest notions on metallic structures - polycrystallinity, solid solutions, segregation, diffusion, deformation - were not elaborated by theoreticians but rather by practitioners. [7]... 

FIG. 8. A schematic overview of how clusters are related to many areas of modern materials science, micro electronics, mesoscopic physics when the sizes of the clusters increase. 

Such structure-function relationships form the paradigm of modern materials science, and in the 80s and 90s many academic materials/chemical/polymer engineering departments were rebuilding to include a greater emphasis on soft-matter and electronic properties. They recmited young faculty members with degrees in chemistry or physics, with the result that the boundaries between these various departments has become blurred. 

As a consequence, numerous approaches to create super-hydrophobic textile surfaces have been published in the last years from a number of research groups aiming to replace the conventional wet-chemical finish using fluorocarbons. The scope of this paper is to give an introduction to several novel approaches to create durable hydrophobic finishes on textile substrates, which make use of developments in modern materials science, which either have been investigated in fundamental research or are already applied in various industrial branches. Experimental data from recent studies by the authors are used to detail several of the concepts. 

The defects that can occur in BCP nanopatterns can take several forms and it is beyond the scope of this chapter to detail these in full, however, it is worth providing a general overview. They take the form of many structural defects in other systems and can be broadly described as dislocations and disclinations and a good review is provided elsewhere (Krohner and Antony, 1975). In the simplest explanation, a dislocation is a defect that affects the positional order of atoms in a lattice and the displacement of atoms from their ideal positions is a symmetry of the medium Screw and edge dislocations representing insertion of planes or lines of atoms are typical of dislocations. For a discUnation the defects (lines, planes or 3D shapes) the rotational symmetry is altered through displacements that do not comply with the symmetry of the environment. Kleman and Friedel give an excellent review of the application of these topics to modern materials science (Kleman and Friedel, 2008). 

Modern materials science is mainly based on three sections of physical chemistry, namely, the thermodynamics of multicomponent multiphase systems, the kinetics of phase transitions, and morphology. I he location of the configurative point on the state diagram, the trajectory ajid velocity of its transfer determine the type of phase separation and the mechanism of kinetics, which, in turn, determines the morphology of the system, and, finally, the performance of materials and articles. 

M.J. Yacamdn and R. Mehl, The role of nano sized particles. A frontier in modern materials science, from nanoelectronics to environmental problems Medalist, Award Metall. Mat. Trans. A, vol. 29, no. 3, pp. 713-716,1998. 

Modern materials science is characterized by a close interplay with physics, chemistry, and biology. This is specially true of nanomaterials, as vividly demonstrated by the methods of synthesis employed for these materials. On the one hand, are the top-down methods which rely on continuous breakup of bulk matter while on the other are the bottom-up methods that build up nanomaterials from their constituent atoms. The top-down and bottom-up approaches can also be considered as physical and chemical methods, respectively. A variety of hybrid methods have since come into being. 

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