Application of nano-structures requires knowledge of their fundamental physical (mechanical, electro-magnetic, optical, etc.) characteristics. Thermodynamic properties associated with phonon displacements through the nano-samples are particularly interesting. Independent of the type of lattices, the thermodynamics of their subsystems (electrons, excitons, spin waves, etc.) is determined when the subsystem is in thermodynamic equilibrium with phonons. Besides, the acoustical characteristics as well as conductive and superconductive properties etc. could not be realistically explained without phonons. The fact which must be especially pointed out is that the role of phonons in nanostructures is much more impressive than in bulk structures. The main fact concerning phonon properties in nanostructures is the absence of the so-called acoustic phonons: for the exciting of phonons in nanostructures activation energy different from zero is necessary. These unexpected characteristics require revision of all conclusions obtained by bulk theories of phonons. Therefore, the contribution of phonon subsystems to thermodynamic is the first step in a research of nanostructure properties.

The monograph is devoted to the investigation of physical processes that govern the phonon transport in bulk and nanoscale single-crystal samples of cubic symmetry. Special emphasis is given to the study of phonon focusing in cubic crystals and its influence on the boundary scattering and lattice thermal conductivity of bulk materials and nanostructures.

With the development of the scanning tunneling microscope, nanoscience became an important discipline. Single atoms could be manipulated in a controlled manner, and it became possible to change matter at its 'ultimate' level; it is the level on which the properties of matter emerge. This possibility enables to construct and to produce devices, materials, etc. with very small sizes and completely new properties. That opens up new perspectives for technology and is in particular relevant in connection with nano-engineering.Nanosystems are unimaginably small and very fast. No doubt, this is an important characteristic. But there is another feature, possibly more relevant, in connection with nanoscience and nanotechnology. The essential point here is that we work at the 'ultimate level'. This is the smallest level at which the properties of our world emerge, at which functional matter can exist. In particular, at this level biological individuality comes into existence. This situation can be expressed in absolute terms: This is not only the strongest material ever made, this is the strongest material it will ever be possible to make (D Ratner and M Ratner, Nanotechnology and Homeland Security). This is a very general statement. All aspects of matter are concerned here. Through the variation of the composition various forms of matter emerge with different items.Nanosystems are usually small, but they offer nevertheless the possibility to vary the structure of atomic (molecular) ensembles, creating a diversity of new material-specific properties. A large variety of experimental possibilities come into play and flexible theoretical tools are needed at the basic level. This is reflected in the different disciplines: In nanoscience and nanotechnology we have various directions: Materials science, functional nanomaterials, nanoparticles, food chemistry, medicine with brain research, quantum and molecular computing, bioinformatics, magnetic nanostructures, nano-optics, nano-electronics, etc.The properties of matter, which are involved within these nanodisciplines, are ultimate in character, i.e., their characteristic properties come into existence at this level. The book is organized in this respect.

This volume is devoted to the electron and phonon energy states of inorganic layered crystals. The distinctive feature of these low-dimensional materials is their easy mechanical cleavage along planes parallel to the layers. This feature implies that the chemical binding within each layer is much stronger than the binding between layers and that some, but not necessarily all, physical properties of layered crystals have two-dimensional character. In Wyckoff's Crystal Structures, SiC and related com pounds are regarded as layered structures, because their atomic layers are alternately stacked according to the requirements of cubic and hexagonal close-packing. How ever, the uniform (tetrahedral) coordination of the atoms in these compounds excludes the kind of structural anisotropy that is fundamental to the materials dis cussed in this volume. An individual layer of a layered crystal may be composed of either a single sheet of atoms, as in graphite, or a set of up to five atomic sheets, as in Bi2 Te3' A layer may also have more complicated arrangements of the atoms, as we find for example in Sb S . But the unique feature common to all these materials is 2 3 the structural anisotropy, which directly affects their electronic and vibrational properties. The nature of the weak interlayer coupling is not very well understood, despite the frequent attribution of the coupling in the literature to van der Waals forces. Two main facts, however, have emerged from all studies.

With the development of the scanning tunneling microscope, nanoscience became an important discipline. Single atoms could be manipulated in a controlled manner, and it became possible to change matter at its 'ultimate' level; it is the level on which the properties of matter emerge. This possibility enables to construct and to produce devices, materials, etc. with very small sizes and completely new properties. That opens up new perspectives for technology and is in particular relevant in connection with nano-engineering.Nanosystems are unimaginably small and very fast. No doubt, this is an important characteristic. But there is another feature, possibly more relevant, in connection with nanoscience and nanotechnology. The essential point here is that we work at the 'ultimate level'. This is the smallest level at which the properties of our world emerge, at which functional matter can exist. In particular, at this level biological individuality comes into existence. This situation can be expressed in absolute terms: This is not only the strongest material ever made, this is the strongest material it will ever be possible to make (D Ratner and M Ratner, Nanotechnology and Homeland Security). This is a very general statement. All aspects of matter are concerned here. Through the variation of the composition various forms of matter emerge with different items.Nanosystems are usually small, but they offer nevertheless the possibility to vary the structure of atomic (molecular) ensembles, creating a diversity of new material-specific properties. A large variety of experimental possibilities come into play and flexible theoretical tools are needed at the basic level. This is reflected in the different disciplines: In nanoscience and nanotechnology we have various directions: Materials science, functional nanomaterials, nanoparticles, food chemistry, medicine with brain research, quantum and molecular computing, bioinformatics, magnetic nanostructures, nano-optics, nano-electronics, etc.The properties of matter, which are involved within these nanodisciplines, are ultimate in character, i.e., their characteristic properties come into existence at this level. The book is organized in this respect.