Pressure Induced Phase Transformations In Quartz And Quartz Like Systems

This book is a printed edition of the Special Issue of Crystals entitled Pressure-Induced Phase Transformations. It includes selected articles on the behavior of matter under high-pressure and high-temperature conditions, describing and discussing contemporary achievements, which were selected based on their relevance and scientific quality.

The study of phase transitions in materials under high pressure and high temperature is a very active research field. In the last few decades, many important discoveries have been made thanks to the development of experimental techniques and computer simulation methods. Many of these achievements affect various research fields ranging from solid-state physics, chemistry, and materials science to geophysics. They not only involve deepening knowledge on solid-solid phase transitions, but also a better understanding of melting under compression. These modern discoveries, as well as the impact of pressure on structural, chemical, and physical properties, are central to the current Special Issue. Amongst other topics, it places particular emphasis on phase transitions and their effects on different physical properties.

As laboratories replace heavy hydraulic presses and bulky high-pressure chambers with miniature diamond anvils, traditional heaters with laser heating, and continue to improve methods of shock compression, there has been considerable new data obtained from the high-pressure, high-temperature modification of pure elements. The dense metallic modification of elements shows the potential for achieving superconductivity akin to theoretical predictions. Phase Transformations of Elements Under High Pressure contains the latest theoretical and experimental information on nearly 100 elements, including first-and second-phase transitions, melting lines, crystal structures of stable and metastable phases, stability of polymorphic modifications, and other useful properties and data. It emphasizes features such as changes in the liquid state, amorphization, and metallization, and provides temperature-pressure diagrams for every element. The book also describes the transitions of polymeric forms of fullerene, crystal modifications of elements stable under high pressures, and provides data that confirms their superconducting and magnetic properties. This handbook will be a lasting reference for scientists in a broad range of disciplines, including solid-state physics, chemistry, crystallography, mineralogy, and materials science.

Presenting some of the most recent results of Russian research into shock compression, as well as historical overviews of the Russian research programs into shock compression, this volume will provide Western researchers with many novel ideas and points of view. The chapters in this volume are written by leading Russian specialists various fields of high-pressure physics and form accounts of the main researches on the behavior of matter under shock-wave interaction. The experimental portions contain results of studies of shock compression of metals to high and ultra-high pressure, shock initiation of polymorphic transformations, strength, fracture and fragmentation under shock compression, and detonation of condensed explosives. There are also chapters on theoretical investigations of shock-wave compression and plasma states in regimes of high-pressure and high- temperature. The topics of the book are of interest to scientists and engineers concerned with questions of material behavior under impulsive loading and to the equation of state of matter. Application is to questions of high-speed impact, inner composition of planets, verification of model representations of material behavior under extreme 1oading conditions, syntheses of new materials, development of new technologies for material processing, etc. Russian research differs from much of the Western work in that it has traditionally been wider-ranging and more directed to extremes of response than to precise characterization of specific materials and effects. Western scientists could expect to benefit from the perspective gained from close knowledge of the Russian work.

In recent interactions with industrial companies it became quite obvious, that the search for new materials with strong anisotropic properties are of paramount importance for the development of new advanced electronic and magnetic devices. The questions concerning the tailoring of materials with large anisotropic electrical and thermal conductivity were asked over and over again. It became also quite clear that the chance to answer these questions and to find new materials which have these desired properties would demand close collaborations between scientists from different fields. Modem techniques ofcontrolled materials synthesis and advances in measurement and modeling have made clear that multiscale complexity is intrinsic to complex electronic materials, both organic and inorganic. A unified approach to classes of these materials is urgently needed, requiring interdisciplinary input from chemistry, materials science, and solid state physics. Only in this way can they be controlled and exploited for increasingly stringent demands oftechnology. The spatial and temporal complexity is driven by strong, often competing couplings between spin, charge and lattice degrees offreedom, which determine structure-function relationships. The nature of these couplings is a sensitive function of electron-electron, electron-lattice, and spin-lattice interactions; noise and disorder, external fields (magnetic, optical, pressure, etc. ), and dimensionality. In particular, these physical influences control broken-symmetry ground states (charge and spin ordered, ferroelectric, superconducting), metal-insulator transitions, and excitations with respect to broken-symmetries created by chemical- or photo-doping, especially in the form of polaronic or excitonic self-trapping.

Volume 39 of Reviews in Mineralogy and Geochemistry about Transformation Processes in Minerals summarises the current state of the art. The selection of transformation processes covered here is by no means comprehensive, but represents a coherent view of some of the most important processes which occur specifically in minerals. Contents: Rigid unit modes in framework structures Strain and elasticity at structural phase transitions in minerals Mesoscopic twin patterns in ferroelastic and co-elastic minerals High-pressure structural phase transitions Order-disorder phase transitions Phase transformations induced by solid solution Magnetic transitions in minerals NMR spectroscopy of phase transitions in minerals Insights into phase transformations from Mössbauer spectroscopy Hard mode spectroscopy of phase transitions Synchrotron studies of phase transformations Radiation-induced amorphization

Volume 37 of Reviews in Mineralogy, divided into three sections, begins with an overview (Chapter 1) of the remarkable advances in the ability to subject minerals-not only as pristine single-crystal samples but also complex, natural mineral assemblages-to extreme pressure-temperature conditions in the laboratory. These advances parallel the development of an arsenal of analytical methods for measuring mineral behavior under those conditions. This sets the stage for section two (Chapters 2-8) which focuses on high-pressure minerals in their geological setting as a function of depth. This top-down approach begins with what we know from direct sampling of high-pressure minerals and rocks brought to the surface to detailed geophysical observations of the vast interior. The third section (Chapters 9-19) presents the material fundamentals, starting from properties of a chemical nature, such as crystal chemistry, thermochemistry, element partitioning, and melting, and moving toward the domain of mineral physics such as melt properties, equations of state, elasticity, rheology, vibrational dynamics, bonding, electronic structure, and magnetism. The Review thus moves from the complexity of rocks to their mineral components and finally to fundamental properties arising directly from the play of electrons and nuclei. This volume was prepared for a short course by the same title, organized by Russell J. Hemley and Ho-kwang Mao and sponsored by the Mineralogical Society of America, December 4-6, 1998 on the campus of the University of California at Davis.