The goal of the series Physics and Chemistry of Materials with Layered
Structures is to give a critical survey of our present knowledge on a
large family of materials which can be described as solids containing
molecules which in two dimensions extend to infinity and which are
loosely stacked on top of each other to form three- dimensional
crystals. Of course, the physics and chemistry of these crystals are
specific chapters in ordinary solid state science, and many a scientist
hunting for new phenomena has in the past been disappointed to find that
materials with layered structures are not entirely exotic. Their
electron and phonon states are not two- dimensional, and the high hopes
held by some for spectacular dimensionality effects in superconductivity
were shattered. Nevertheless, the structural features and their physical
and chemical consequences singularize layered structures sufficiently to
make them a fascinating subject of research. This is all the more true
since they are met in insulators and semiconductors as well as in normal
and superconducting metals. Although for the time being the series is
intentionally limited to cover inorganic materials only, the many known
organic layered structures may well be the subject of future volumes.
Among the noteworthy peculiarities of layered structures, we mention
specific growth mechanisms and crystal habits. Polytypism is very common
and it is fasci- nating indeed to find up to 240 different polytypes in
the same chemical substance.