The study of materials properties under extreme conditions has made considerable progress over the past decade due to both improvements in experimental techniques and advanced modeling methods. The availability of accurate models is crucial in order to analyze experimental results obtained in extreme conditions of pressure and temperature where experimental data can be scarce. Among theoretical models, ab initio simulations are playing an increasingly important role due to their ability to predict materials properties without the need for any experimental input. Ab initio simulations also allow for an exploration of materials properties in conditions that are unachievable using controlled experiments--such as e.g. the conditions prevailing in the core of large planets. In that limit, they constitute the only quantitative model of condensed matter available today. In this article, we review the current status of ab initio simulations and discuss examples of recent applications in which numerical simulations have provided an essential complement to experimental data.

Materials Under Extreme Conditions: Recent Trends and Future Prospects analyzes the chemical transformation and decomposition of materials exposed to extreme conditions, such as high temperature, high pressure, hostile chemical environments, high radiation fields, high vacuum, high magnetic and electric fields, wear and abrasion related to chemical bonding, special crystallographic features, and microstructures. The materials covered in this work encompass oxides, non-oxides, alloys and intermetallics, glasses, and carbon-based materials. The book is written for researchers in academia and industry, and technologists in chemical engineering, materials chemistry, chemistry, and condensed matter physics. Describes and analyzes the chemical transformation and decomposition of a wide range of materials exposed to extreme conditions Brings together information currently scattered across the Internet or incoherently dispersed amongst journals and proceedings Presents chapters on phenomena, materials synthesis, and processing, characterization and properties, and applications Written by established researchers in the field

High-pressure materials research has been revolutionized in the past few years due to technological breakthroughs in the diamond anvil cell (DAC), shock wave compression and molecular dynamic simulation (MD) methods. The application of high pressure, especially together with high temperature, has revealed exciting modifications of physical and chemical properties even in the simplest molecular materials.Besides the fundamental importance of these studies to understand the composition and the dynamics of heart and planets' interior, new materials possessing peculiar characteristics of hardness and composition have been synthesized at very high pressure, while unexpected chemical reactions of simple molecules to polymers and amorphous compounds have been found at milder conditions.The variety of the phenomena observed in these extreme conditions and of the materials involved provides a common ground bridging scientific communities with different cultural and experimental backgrounds. This monograph will provide a timely opportunity to report on recent progress in the field.

This book presents recently developed computational approaches for the study of reactive materials under extreme physical and thermodynamic conditions. It delves into cutting edge developments in simulation methods for reactive materials, including quantum calculations spanning nanometer length scales and picosecond timescales, to reactive force fields, coarse-grained approaches, and machine learning methods spanning microns and nanoseconds and beyond. These methods are discussed in the context of a broad range of fields, including prebiotic chemistry in impacting comets, studies of planetary interiors, high pressure synthesis of new compounds, and detonations of energetic materials. The book presents a pedagogical approach for these state-of-the-art approaches, compiled into a single source for the first time. Ultimately, the volume aims to make valuable research tools accessible to experimentalists and theoreticians alike for any number of scientific efforts, spanning many different types of compounds and reactive conditions.

In this reprint, the underlying damage mechanisms of materials used under extreme conditions are explored using computer simulation and modelling methods, presenting important information to predict the lifetime of related facilities. The scope of this reprint embraces numerical work on material responses to extreme conditions, such as high-speed impact or loading, neutron or ion irradiation, and high-pressure and/or high-temperature environments. Related simulation results based on the first principle method, molecular dynamics, and finite element methods are reported. Results of various topics have been reported by papers collected in this book, for example, including fitting a better empirical potential, diffusion of atoms on surface, corrosion, interaction between different defects, elastic constants calculations, effect of hot press forming on collision toughness and energy distribution, and influence of radiation defects on the thermo-mechanical properties of UO2. Furthermore, a review about the experiments and models for the effect of strain rate on NiTi shape memory alloys (SMAs) has also been included in this reprint. These new results present new knowledge for understanding the damage mechanisms of materials under extreme conditions, which would be useful not only for researchers in these fields but also for new readers to learn about basic concepts and current research progress to better understand the response of materials under extreme conditions.

In this book, the underlying damage mechanisms of materials used under extreme conditions are explored using computer simulation and modelling methods, presenting important information to predict the lifetime of related facilities. The scope of this book embraces numerical work on material responses to extreme conditions, such as high-speed impact or loading, neutron or ion irradiation, and high-pressure and/or high-temperature environments. Related simulation results based on the first principle method, molecular dynamics, and finite element methods are reported. Results of various topics have been reported by papers collected in this book, for example, including fitting a better empirical potential, diffusion of atoms on surface, corrosion, interaction between different defects, elastic constants calculations, effect of hot press forming on collision toughness and energy distribution, and influence of radiation defects on the thermo-mechanical properties of UO2. Furthermore, a review about the experiments and models for the effect of strain rate on NiTi shape memory alloys (SMAs) has also been included in this book. These new results present new knowledge for understanding the damage mechanisms of materials under extreme conditions, which would be useful not only for researchers in these fields but also for new readers to learn about basic concepts and current research progress to better understand the response of materials under extreme conditions.

Recent advances in high pressure diamond anvil cell techniques and synchrotron radiation characterization methods have enabled investigation of a wide range of materials properties in-situ under extreme conditions. High pressure studies have made significant contribution to our understanding in a number of scientific fields, e.g. condensed matter physics, chemistry, Earth and planetary sciences, and material sciences. Pressure, as a fundamental thermodynamic variable, can induce changes in the electronic and structural configuration of a material, which in turn can dramatically alter its properties. The novel phases and new compounds existing at high pressure have improved our basic understanding of bonding and interactions in condensed matter. This dissertation focuses on how pressure affects materials' bonding and electronic structures in two types of systems: hydrogen rich molecular compounds and strongly correlated transition metal oxides. The interaction of boranes and hydrogen was studied using optical microscopy and Raman spectroscopy and their hydrogen storage potential is discussed in the context of practical applications. The pressure-induced behavior of the SiH4 + H2 binary system and the formation of a newly formed compound SiH4(H2)2 were investigated using a combination of optical microscopy, Raman spectroscopy and x-ray diffraction. The experimental work along with DFT calculations on the electronic properties of the compound up to the possible metallization pressure, indicated that there are strong intermolecular interactions between SiH4 and H2 in the condensed phase. By using a newly developed synchrotron x-ray spectroscopy technique, we were able to follow the evolution of the 3d band of a 3d transition metal oxide, Fe2O3 under pressure, which experiences a series of structural, electronic and spin transitions at approximately 50 GPa. Together with theoretical calculations we revisited its electronic phase transition mechanism, and found that the electronic transitions are reflected in the pre-edge region.