Download or read book A First Principles Study of Highly Anharmonic and Dynamically Disordered Solids written by Johan Klarbring and published by Linköping University Electronic Press. This book was released on 2020-05-06 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is a first-principles theoretical investigation of solid materials with high degrees of anharmonicity. These are systems where the dynamics of the constituent atoms is too complex to be well-described by a set of uncoupled harmonic oscillators. While theoretical studies of such systems pose a significant challenge, they are under increasing demand due to the prevalence of these sytems in next-generation technological applications. Indeed, very anharmonic systems are ubiquitous in envisioned materials for future solid-state batteries and fuel-cells, thermoelectrics and optoelectronics. In some of these cases, the anharmonicity is a “side-effect” that simply has to be dealt with in order to accurately model certain properties, while in other cases the anharmonicity is the origin of the high-performance of the material. There are two main parts to the thesis: The first is on materials with perovskite-related structures. This is a very large class of materials, members of which are typically highly anharmonic, not least in relation to a series of complex phase transformations between different structural modifications. In the thesis, I have studied a specific class of such phase-transformations that relate to tilting of the framework of octahedra that make up the structure. The oxide CaMnO3 and a set of inorganic halide perovskites were taken as model systems. The results shed some light on the experimentally observed differences between the local and average atomic structure in these systems. I have further studied Cs2AgBiBr6, a member of the so-called lead-free halide double perovskites. I rationalized its temperature induced phase transformation and found high degrees of anharmonicity and ultra-low thermal conductivity. Finally, I studied the influence of nuclear quantum effects, which are often ignored in computational modelling, on the structure and bonding in the hybrid organic-inorganic lead-halide perovskite, CH3NH3PbI3. The second part of the thesis deals with theoretical studies of the phase stability of dynamically disordered solids. These are solids which have some sort of time-averaged long-range order, characteristic of a crystalline solid, but where the anharmonicity is so strong that the basic concept of an equilibrium atomic position cannot be statically assigned to all atoms. Examples include certain solids with very fast ionic conduction, so called superionics, and solids with rotating molecular units. This absence of equilibrium atomic positions makes many standard computational techniques to evaluate phase-stability inapplicable. I outline a method to deal with this issue, which is based on a stress-strain thermodynamic integration on a deformation path from an ordered variant to the dynamically disordered phase itself. I apply the method to study the phase stability of the high-temperature ?-phase of Bi2O3, which is the fastest know solid oxide ion conductor, and to Li2C2, whose high temperature cubic phase contains rotating C2 dimers. The thesis exemplifies the need to go beyond many of the standard approximations used in first-principles computational materials science if accurate theoretical predictions are to be made. This is true, in particular, for many emerging material classes in the field of energy materials. I den konventionella teoretiska modellen för ett (kristallint) fast material antags varje atom kunna tillordnas en jämviktsposition. Rörelsen av atomerna runt dessa jämviktspositioner antags sedan ofta vara harmoniskt, d.v.s. hyfsat kunna beskrivs i termer av en samling (kvantmekaniska) fjädrar. Denna avhandling behandlar teori- och beräkningsstudier av material där ett eller båda av dessa antaganden inte är giltiga, så kallade anharmoniska material. En nogrann teoretisk behandling av sådana material är ofta ordentligt utmanande. I takt med en snabb teknologiska utveckling ställs allt mer specifika och stränga krav på de material som behövs för diverse applikationer. Inom flertalet områden dyker då denna typ av komplexa och anharmoniska material upp som potentiella kandidater. Till exempel som fastelektrolyter för batterier och bränsleceller eller som solcellsmaterial. Inom vissa applikationer är denna anharmonicitet en bieffekt som man helt enkelt måste ta hänsyn till för att kunna göra noggranna teoretiska förutsägelser om diverse materialegenskaper, i andra fall är anharmoniciteten själva ursprunget för materialets goda egenskaper. I den första delen av avhandlingen behandlar jag material som har, eller är nära relaterade till, den så kallade perovskitstrukturen. Detta är en väldigt stor klass av material, och strukturen dyker därför upp inom en mängd olika tillämpningar, inte minst i lovande solcellsmaterial. Dessa material är ofta mycket anharmoniska, vilket tar sig uttryck bland annat i en rad komplexa fastransformationer mellan olika typer av perovskitmodifikationer. I perovskitoxiden CaMnO3, samt i en samling halogenperovskiter, har jag har studerat en specifik typ av fastransformationer som tillkommer på grund av rotationer av de oktaedrar som utgör en del av strukturen. Jag har fortsatt studerat den väldigt kraftiga anharmoniciteten i den så kallade blyfria halogendubbelperovskiten Cs2AgBiBr6, och slutligen har jag studerat hur en kvantmekanisk behandling av atomkärnorna, något som oftast inte görs, påverkar materialegenskaper i CH3NH3PbI3, en så kallad hybrid organisk-inorganisk bly-halogenperovskit, som är ett extremt lovande solcellsmaterial. I den andra delen av avhandlingen studerar jag dynamiskt oordnade fasta material. I dessa material är atomernas rörelse för komplex för att varje atom ska kunna tilldellas en statisk jämviktsposition. Material i denna klass är, till exempel, lovande som fastelektrolyter i bränsleceller och batterier. Mer specifikt studerar jag en typ av fasövergång, från en ordnad fas till en fas med dynamisk oordning, som ofta sker när dessa material värms upp. Jag introducerar en beräkningsmetod för att utvärdera deras fasstabilitet. Metoden är baserad på en så kallad termodynamisk integration, utförd mellan en ordnad variant och den dynamiskt oordnade fasen själv. Metoden gör det möjligt att beräkna fastransformationstemperaturer i denna typ av material. Jag applicerar metoden på Bi2O3, som i sin ?-fas är det fasta material med högst känd syrejonledningsförmåga, samt på Li2C2 vars kubiska fas innehåller roterande C2 molekyler. Resultaten stämmer bra överens med kända experimentella mätningar.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2540 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1986 with total page 820 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Science Abstracts written by and published by . This book was released on 1992 with total page 1228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics of Phonons written by Gyaneshwar P. Srivastava and published by Routledge. This book was released on 2019-07-16 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt: There have been few books devoted to the study of phonons, a major area of condensed matter physics. The Physics of Phonons is a comprehensive theoretical discussion of the most important topics, including some topics not previously presented in book form. Although primarily theoretical in approach, the author refers to experimental results wherever possible, ensuring an ideal book for both experimental and theoretical researchers. The author begins with an introduction to crystal symmetry and continues with a discussion of lattice dynamics in the harmonic approximation, including the traditional phenomenological approach and the more recent ab initio approach, detailed for the first time in this book. A discussion of anharmonicity is followed by the theory of lattice thermal conductivity, presented at a level far beyond that available in any other book. The chapter on phonon interactions is likewise more comprehensive than any similar discussion elsewhere. The sections on phonons in superlattices, impure and mixed crystals, quasicrystals, phonon spectroscopy, Kapitza resistance, and quantum evaporation also contain material appearing in book form for the first time. The book is complemented by numerous diagrams that aid understanding and is comprehensively referenced for further study. With its unprecedented wide coverage of the field, The Physics of Phonons will be indispensable to all postgraduates, advanced undergraduates, and researchers working on condensed matter physics.
Download or read book Halide Perovskites written by Tze-Chien Sum and published by John Wiley & Sons. This book was released on 2019-03-25 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Real insight from leading experts in the field into the causes of the unique photovoltaic performance of perovskite solar cells, describing the fundamentals of perovskite materials and device architectures. The authors cover materials research and development, device fabrication and engineering methodologies, as well as current knowledge extending beyond perovskite photovoltaics, such as the novel spin physics and multiferroic properties of this family of materials. Aimed at a better and clearer understanding of the latest developments in the hybrid perovskite field, this is a must-have for material scientists, chemists, physicists and engineers entering or already working in this booming field.
Download or read book Density Functional Theory written by David S. Sholl and published by John Wiley & Sons. This book was released on 2011-09-20 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Demonstrates how anyone in math, science, and engineering can master DFT calculations Density functional theory (DFT) is one of the most frequently used computational tools for studying and predicting the properties of isolated molecules, bulk solids, and material interfaces, including surfaces. Although the theoretical underpinnings of DFT are quite complicated, this book demonstrates that the basic concepts underlying the calculations are simple enough to be understood by anyone with a background in chemistry, physics, engineering, or mathematics. The authors show how the widespread availability of powerful DFT codes makes it possible for students and researchers to apply this important computational technique to a broad range of fundamental and applied problems. Density Functional Theory: A Practical Introduction offers a concise, easy-to-follow introduction to the key concepts and practical applications of DFT, focusing on plane-wave DFT. The authors have many years of experience introducing DFT to students from a variety of backgrounds. The book therefore offers several features that have proven to be helpful in enabling students to master the subject, including: Problem sets in each chapter that give readers the opportunity to test their knowledge by performing their own calculations Worked examples that demonstrate how DFT calculations are used to solve real-world problems Further readings listed in each chapter enabling readers to investigate specific topics in greater depth This text is written at a level suitable for individuals from a variety of scientific, mathematical, and engineering backgrounds. No previous experience working with DFT calculations is needed.
Download or read book Electrons and Phonons written by J.M. Ziman and published by Oxford University Press. This book was released on 2001-02 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a classic text of its time in condensed matter physics.
Download or read book X Ray Absorption and X Ray Emission Spectroscopy written by Jeroen A. van Bokhoven and published by John Wiley & Sons. This book was released on 2016-01-08 with total page 896 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the last two decades, remarkable and often spectacular progress has been made in the methodological and instrumental aspects of x–ray absorption and emission spectroscopy. This progress includes considerable technological improvements in the design and production of detectors especially with the development and expansion of large-scale synchrotron reactors All this has resulted in improved analytical performance and new applications, as well as in the perspective of a dramatic enhancement in the potential of x–ray based analysis techniques for the near future. This comprehensive two-volume treatise features articles that explain the phenomena and describe examples of X–ray absorption and emission applications in several fields, including chemistry, biochemistry, catalysis, amorphous and liquid systems, synchrotron radiation, and surface phenomena. Contributors explain the underlying theory, how to set up X–ray absorption experiments, and how to analyze the details of the resulting spectra. X-Ray Absorption and X-ray Emission Spectroscopy: Theory and Applications: Combines the theory, instrumentation and applications of x-ray absorption and emission spectroscopies which offer unique diagnostics to study almost any object in the Universe. Is the go-to reference book in the subject for all researchers across multi-disciplines since intense beams from modern sources have revolutionized x-ray science in recent years Is relevant to students, postdocurates and researchers working on x-rays and related synchrotron sources and applications in materials, physics, medicine, environment/geology, and biomedical materials
Download or read book Physics Uspekhi written by and published by . This book was released on 2001 with total page 752 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1978 with total page 920 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book S rie Recherches Sur Les D formations written by and published by . This book was released on 1995 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Frustrated Magnetism written by Claudine Lacroix and published by Springer Science & Business Media. This book was released on 2011-01-12 with total page 682 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of highly frustrated magnetism has developed considerably and expanded over the last 15 years. Issuing from canonical geometric frustration of interactions, it now extends over other aspects with many degrees of freedom such as magneto-elastic couplings, orbital degrees of freedom, dilution effects, and electron doping. Its is thus shown here that the concept of frustration impacts on many other fields in physics than magnetism. This book represents a state-of-the-art review aimed at a broad audience with tutorial chapters and more topical ones, encompassing solid-state chemistry, experimental and theoretical physics.
Download or read book Handbook of Materials Modeling written by Sidney Yip and published by Springer Science & Business Media. This book was released on 2007-11-17 with total page 2903 pages. Available in PDF, EPUB and Kindle. Book excerpt: The first reference of its kind in the rapidly emerging field of computational approachs to materials research, this is a compendium of perspective-providing and topical articles written to inform students and non-specialists of the current status and capabilities of modelling and simulation. From the standpoint of methodology, the development follows a multiscale approach with emphasis on electronic-structure, atomistic, and mesoscale methods, as well as mathematical analysis and rate processes. Basic models are treated across traditional disciplines, not only in the discussion of methods but also in chapters on crystal defects, microstructure, fluids, polymers and soft matter. Written by authors who are actively participating in the current development, this collection of 150 articles has the breadth and depth to be a major contributor toward defining the field of computational materials. In addition, there are 40 commentaries by highly respected researchers, presenting various views that should interest the future generations of the community. Subject Editors: Martin Bazant, MIT; Bruce Boghosian, Tufts University; Richard Catlow, Royal Institution; Long-Qing Chen, Pennsylvania State University; William Curtin, Brown University; Tomas Diaz de la Rubia, Lawrence Livermore National Laboratory; Nicolas Hadjiconstantinou, MIT; Mark F. Horstemeyer, Mississippi State University; Efthimios Kaxiras, Harvard University; L. Mahadevan, Harvard University; Dimitrios Maroudas, University of Massachusetts; Nicola Marzari, MIT; Horia Metiu, University of California Santa Barbara; Gregory C. Rutledge, MIT; David J. Srolovitz, Princeton University; Bernhardt L. Trout, MIT; Dieter Wolf, Argonne National Laboratory.
Download or read book Introduction to Lattice Dynamics written by Martin T. Dove and published by Cambridge University Press. This book was released on 1993-10-21 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: The vibrations of atoms inside crystals - lattice dynamics - is basic to many fields of study in the solid-state and mineral sciences. This book provides a self-contained text that introduces the subject from a basic level and then takes the reader through applications of the theory.
Download or read book Dynamical Theory of Crystal Lattices written by Max Born and published by Oxford University Press on Demand. This book was released on 1988 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: At the time of its original publication this reissued 'classic' text, co-written by the Nobel Laureate of 1954, Max Born, represented the final account of the subject and in many ways it still does. The book is divided into four sections. The first of these is very general in nature and dealswith the general statistical mechanics of ideal lattices, leading to the electric polarizability and to the scattering of light. The second part deals with the properties of long lattice waves; the third with thermal properties and the fourth with optical properties.
