This book is devoted to the theme of crystallographic studies at high pressure, with emphasis on the phenomena characteristic to the compressed state of matter, as well as experimental and theoretical techniques, used to study these phenomena. As a thermodynamic parameter, pressure is remarkable in many ways. It spans in the visible universe over sixty orders of magnitude, from the non-equilibrium pressure of hydrogen in intergalactic space, to the kind of pressure encountered within neutron stars. In laboratory, it provides unique possibility to control structure and properties of materials, dramatically alter electronic properties, break existing, or form new chemical bonds. This agenda naturally encompasses elements of physics (properties, structure and transformations), chemistry (reactions, transport), materials science (new materials) and engineering (mechanical properties); in addition it has direct applications and implications for geology (minerals in deep Earth environments), planetary sciences, biology and medicine (deep sea ecosystems, membranes, protein and nucleic acid folding, origins of life, deactivation of viruses and toxins). Beyond its specificity, high-pressure science finds direct or indirect (e.g. economic) applications in several fields of modern technology, such as mechanical engineering, optoelectronics and spintronics, nanotechnology, pharmaceutical industry and food processing.
