This volume comprised the proceedings of a NATO Advanced Study Institute held in Geilo, Norway between 29 March and 9 April 1987. Al though the principal support for the meeting was provided by the NATO Cornrni ttee for Scientific Affairs, a number of additional sponsors also contributed. Additional funds were received from: Institutt for Energiteknikk (Norway) The Norwegian Research Council for Science and Humanities NORDITA (Denmark) VISTA (Norway) The organizing cornrni ttee would like to take this opportunity to thank all sponsors for their help in promoting an exciting and rewarding meeting. This Study Institute was the ninth of a series of meetings held in Geilo on subjects related to phase transitions and was a natural successor to the 1985 meeting on Scaling Phenomena in Disordered Systems. Many of the subjects discussed at the latter meeting were revisited in 1987, with time dependence as an added feature. Often the common theme was the concept of fractals first introduced into statistical physics some six years ago. However, by no means all disordered systems can be forced into a fractal framework, and many of the lectures reinforced this lesson.

Fractals and disordered systems have recently become the focus of intense interest in research. This book discusses in great detail the effects of disorder on mesoscopic scales (fractures, aggregates, colloids, surfaces and interfaces, glasses and polymers) and presents tools to describe them in mathematical language. A substantial part is devoted to the development of scaling theories based on fractal concepts. In ten chapters written by leading experts in the field, the reader is introduced to basic concepts and techniques in disordered systems and is led to the forefront of current research. This second edition has been substantially revised and updates the literature in this important field.

The author integrates discussions of fractal geometry, surface modeling techniques, and applications to real world problems to provide a comprehensive, accessible overview of the field. His work will equip researchers with the basic tools for measurement and interpretation of data, stimulating more work on these problems and, perhaps, leading to an understanding of the reasons that Nature has adopted this geometry to shape much of our world.

This volume is the proceedings of the NATO Advanced Study Institute, "Diffusion in Materials", held at "Centre Paul Langevin", Aussois, during March 12-25, 1989. There were 105 participants of whom 24 were lecturers and members of the international advisory committee. In addition to the participants from NATO countries, a small number of participants came from Australia, Hungary, Poland and Tunisia. The principal aim of the organizing committee was to bring together scientists of wide interest and expertise in the field of diffusion and to familiarize the young workers in material science with the wide range of theoretical models and methods and of experimental techniques . The Institute was concerned with the study of diffusion and related phenomena in solids which are at the cutting edge of novel technologies. The discussion of basic theories of defects in solids and their transport, with their applications in the understanding of diffusion processes in "simple solids" was followed by the wide range of current theoretical models and methods, experimental techniques and their potential. The lectures on the diffusion in specific materials included : metals, dilute and concentrated alloys, simple and compound semiconductors, stoichiometric and non-stoichiometric oxides, high-Tc compounds, carbides, nitrides, silicates, conducting polymers and thin films, ionic, superionic, amorphous and irradiated materials.

Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing presents the physical and chemical principles of the sol-gel process. The book emphasizes the science behind sol-gel processing with a chapter devoted to applications. The first chapter introduces basic terminology, provides a brief historical sketch, and identifies some excellent texts for background reading. Chapters 2 and 3 discuss the mechanisms of hydrolysis and condensation for nonsilicate and silicate systems. Chapter 4 deals with stabilization and gelation of sols. Chapter 5 reviews theories of gelation and examines the predicted and observed changes in the properties of a sol in the vicinity of the gel point. Chapter 6 describes the changes in structure and properties that occur during aging of a gel in its pore liquor (or some other liquid). The discussion of drying is divided into two parts, with the theory concentrated in Chapter 7 and the phenomenology in Chapter 8. The structure of dried gels is explored in Chapter 9. Chapter 10 shows the possibility of using the gel as a substrate for chemical reactions or of modifying the bulk composition of the resulting ceramic by performing a surface reaction (such as nitridation) on the gel. Chapter 11 reviews the theory and practice of sintering, describing the mechanisms that govern densification of amorphous and crystalline materials, and showing the advantages of avoiding crystallization before sintering is complete. The properties of gel-derived and conventional ceramics are discussed in Chapter 12. The preparation of films is such an important aspect of sol-gel technology that the fundamentals of film formation are treated at length in Chapter 13. Films and other applications are briefly reviewed in Chapter 14. Materials scientists and researchers in the field of sol-gel processing will find the book invaluable.