The two-word title of this book can only give an indication about its content and approach to the subject it deals with. In the course of time, the term has gradually become somewhat blurred. The reason is easy to see: similar problems are now more and more frequently studied by different branches of natural science. The term "mixed crystals" has acquired specific connotations in physics, chemistry, biology, and geology. One and the same term can now serve as a name for things which are either not quite the same or sometimes quite different. And this is precisely what happened to the two words in the title of the book. One of them, the term "crystal", for which crystallography had an un ambiguous definition, is now employed by biologists to describe the structure of cell membranes and by chemists who use it to denote degrees of polymer crystallinity. "Crystal" has thus become a broad term that can help describe any solid, or just a condensed state of a substance, if the solid has a suf ficient degree of order in the arrangement of its components. But the book is called "~lixed Crystals". The other word in its title, the adjective "mixed", has also developed several meanings. It is now thought ap plicable to both homogeneous and heterogeneous systems, that is, to crystals composed of different molecules and also to solids that are a mixture of crys tals with different structures.

``Optical Properties of Mixed Crystals'' is concerned with the description of optical processes in substitutionally disordered semiconductors and insulators which can be basically described through their elementary excitations. Two of the chapters relate to the phonon response including the effect of side bands on electron transitions. Two relate to electronic spectra, one on photoelectron spectroscopy and the other on excitons. A further chapter deals with magnons in magnetic crystals and a final chapter is related to fluctuations and band edge effects.Each chapter deals with a specific class of excitation, but the book makes it clear that the fundamental structure of the excitation spectra, including band formation, band tailing and localisation is common to every type of excitation. The volume shows how some basic concepts and ideas can be widely applied to bring coherence and understanding to a diverse area of solid state physics. It therefore provides an up-to-date summary of the experimental and theoretical situation in an important and rapidly developing field and brings together for the first time a discussion of the many different types of spectra which appear in mixed crystals.

This book focuses on mixed crystals formed by molecular substances. The emphasis lies on the elucidation of the structural and thermodynamic properties of two-component systems. Thanks to the fact that the research efforts have been directed to a number of families of chemically coherent substances, rather than to a collection of isolated systems, the knowledge of mixed crystals has substantially increased. This is reflected by the discovery of several empirical relationships between thermodynamic properties, crystallographic properties, and also between thermodynamic mixing properties and exothermodynamic parameters, such as the structural mismatch between the components of the binary systems. This book is a benchmark for material scientists and a unique starting point for anyone interested in mixed crystals.

In this volume, contributions covering the theoretical and practical aspects of multicomponent crystals provide a timely and contemporary overview of the state-of-the art of this vital aspect of crystal engineering/materials science. With a solid foundation in fundamentals, multi-component crystals can be formed, for example, to enhance pharmaceutical properties of drugs, for the specific control of optical responses to external stimuli and to assemble molecules to allow chemical reactions that are generally intractable following conventional methods. Contents Pharmaceutical co-crystals: crystal engineering and applications Pharmaceutical multi-component crystals: improving the efficacy of anti-tuberculous agents Qualitative and quantitative crystal engineering of multi-functional co-crystals Control of photochromism in N-salicylideneaniline by crystal engineering Quinoline derivatives for multi-component crystals: principles and applications N-oxides in multi-component crystals and in bottom-up synthesis and applications Multi-component crystals and non-ambient conditions Co-crystals for solid-state reactivity and thermal expansion Solution co-crystallisation and its applications The salt-co-crystal continuum in halogen-bonded systems Large horizontal displacements of benzene-benzene stacking interactions in co-crystals Simultaneous halogen and hydrogen bonding to carbonyl and thiocarbonylfunctionality Crystal chemistry of the isomeric N,N’-bis(pyridin-n-ylmethyl)-ethanediamides, n = 2, 3 or 4 Solute・solvent interactions mediated by main group element (lone-pair)・・・π(aryl) interactions

There have been few books devoted to the study of phonons, a major area of condensed matter physics. The Physics of Phonons is a comprehensive theoretical discussion of the most important topics, including some topics not previously presented in book form. Although primarily theoretical in approach, the author refers to experimental results wherever possible, ensuring an ideal book for both experimental and theoretical researchers. The author begins with an introduction to crystal symmetry and continues with a discussion of lattice dynamics in the harmonic approximation, including the traditional phenomenological approach and the more recent ab initio approach, detailed for the first time in this book. A discussion of anharmonicity is followed by the theory of lattice thermal conductivity, presented at a level far beyond that available in any other book. The chapter on phonon interactions is likewise more comprehensive than any similar discussion elsewhere. The sections on phonons in superlattices, impure and mixed crystals, quasicrystals, phonon spectroscopy, Kapitza resistance, and quantum evaporation also contain material appearing in book form for the first time. The book is complemented by numerous diagrams that aid understanding and is comprehensively referenced for further study. With its unprecedented wide coverage of the field, The Physics of Phonons will be indispensable to all postgraduates, advanced undergraduates, and researchers working on condensed matter physics.