Molecular Dynamics Of Glass Forming Systems
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Molecular Dynamics Of Glass Forming Systems
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Author : George Floudas
language : en
Publisher: Springer Science & Business Media
Release Date : 2010-11-25
Molecular Dynamics Of Glass Forming Systems written by George Floudas and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2010-11-25 with Technology & Engineering categories.
Pressure is one of the essential thermodynamic variables that, due to some former experimental difficulties, was long known as the “forgotten variable.” But this has changed over the last decade. This book includes the most essential first experiments from the 1960's and reviews the progress made in understanding glass formation with the application of pressure in the last ten years. The systems include amorphous polymers and glass-forming liquids, polypeptides and polymer blends. The thermodynamics of these systems, the relation of the structural relaxation to the chemical specificity, and their present and future potential applications are discussed in detail. The book provides (a) an overview of systems exhibiting glassy behavior in relation to their molecular structure and provides readers with the current state of knowledge on the liquid-to-glass transformation, (b) emphasizes the relation between thermodynamic state and dynamic response and (c) shows that the information on the pressure effects on dynamics can be employed in the design of materials for particular applications. It is meant to serve as an advanced introductory book for scientists and graduate students working or planning to work with dynamics. Several scientific papers dealing with the effects of pressure on dynamics have appeared in leading journals in the fields of physics in the last ten years. The book provides researchers and students new to the field with an overview of the knowledge that has been gained in a coherent and comprehensive way.
Molecular Dynamics Simulations Of Metallic Glass Formation And Structure
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Author : David C. Riegner
language : en
Publisher:
Release Date : 2016
Molecular Dynamics Simulations Of Metallic Glass Formation And Structure written by David C. Riegner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016 with categories.
Metallic glasses, a class of metal alloys which lack a periodic crystal structure, exhibit exceptional property combinations not accessible by other classes of materials. In spite of promise for widespread application, metallic glasses are difficult to synthesize and understanding of their structure and behavior is limited compared to crystalline alloys. There is no predictive criterion for determining if a particular alloy is capable of forming glass. Numerous glass-forming alloys have been reported, spanning a wide range of possible properties largely through trial and error. Engineering of these materials is difficult, as the connection between atomic structure and macroscopic behavior is not sufficiently developed to exploit particular behaviors in any intentional capacity. Using Molecular Dynamics (MD) simulations, three metallic glass-forming systems, Al-La, Cu-Zr and Cu-Ti-Zr were investigated and compared with the intention of connecting structure to properties and illuminating differences in glass-forming behavior in different alloys. From these simulations a specific mechanism occurring in the liquid, the changing of nearest neighbor environments, was identified and correlated to liquid viscosity. The change in viscosity with temperature, called fragility, was connected to this atomic-scale behavior allowing glass formers and non-glass formers in the Al-La alloys system to be separated from each other. The structure of each glass is readily available from these simulations, and the changes to neighbor environments in Al-La and Cu-Zr alloys, were found to be very similar when comparing the smaller atom type (Al, Cu). Differences in system-wide behavior for Al-La and Cu-Zr can be described based upon the behavior of the larger atom type (La, Zr), where Zr causes a major change in behavior as the majority component not exhibited by even very La-rich alloys. This dissimilarity between La and Zr provides a plausible explanation for Cu-Zr’s superior glass-forming ability compared to Al-La. Experimental data indicated that Cu-Ti-Zr achieve maximum glass-forming ability near Cu51.7Zr36.7Ti11.6. The addition of Ti to the Cu-Zr binary system causes a decrease in nearest-neighbor-switching events and stabilizes structures formed in the liquid, rather than destroying them. Cu51.7Zr36.7Ti11.6 also divides two compositional regions of hardness dependence: above 37% Zr the hardness scales with the concentration of Cu, while below 37% Zr the hardness scales with the concentration of Ti. Based on concepts developed for Al-La and Cu-Zr it was revealed that removing Cu drastically reduced the number of efficiently-packed Cu-centered structures. Below 37% Zr this effect is compensated by an increase in other dense structures but above 37% the effect is both more potent and uncompensated. The loss of these structures is responsible for the changes in yield behavior, and has an effect on the GFA. Finally, extension of these simulations to additional systems requires new multi-component EAM potentials, an essential input for MD simulations. The Rapid Alloy Method for the Production of Accurate General Empirical Potentials (RAMPAGE) was developed to create new multi-component potentials from elemental potentials available in the literature. Using RAMPAGE, the characteristics identified in glass-forming systems can be investigated in other metallic systems.
Mechanical And Viscoelastic Properties Of Glass Forming Polymers In The Bulk And Thin Films
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Author : Ivan Kriuchevskyi
language : en
Publisher:
Release Date : 2017
Mechanical And Viscoelastic Properties Of Glass Forming Polymers In The Bulk And Thin Films written by Ivan Kriuchevskyi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
Focusing on the equilibrium shear modulus Geq of well-known glass-forming polymer model system (sampled by means of MD), we have addressed the general question of how the mechanical properties of the thin polymer films differs from the bulk. Using ”stress fluctuation” formalism we obtained Geq(T) for the bulk and films. It has been demonstrated that in both cases Geq unambiguously separates the fluid state (Geq = 0) from the glass (Geq > 0). We also stressed that Geq for the film does not only depend on film thickness h, but also on tangential pressure that is a consequence of the film preparation procedure.
High Throughput Experimental And Computational Investigations Of Metallic Glass Structure And Glass Forming Ability
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Author : Juan Wang (Mechanical engineer)
language : en
Publisher:
Release Date : 2018
High Throughput Experimental And Computational Investigations Of Metallic Glass Structure And Glass Forming Ability written by Juan Wang (Mechanical engineer) and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018 with Electronic dissertations categories.
Despite intense interest, identifying the structural origin of glass forming ability in metallic alloys remains a challenge due to the difficulty of describing the evolution of the long-range disordered structure from the liquid. In this thesis, we integrate high-throughput experimental methods with computational simulations to study glass formation and the resulting mechanical properties, with a primary focus on the Al-Ni-Zr system. Based on our investigation of the structural and cluster evolution using molecular dynamics simulations, we report the variance of the fraction of different types of atomic clusters in the liquid as a potential parameter to predict glass formation. The predictive power of the variance in the liquid state was verified by comparison with alloy libraries synthesized by a highly efficient laser deposition technique. Experimentally, glass formation was found over a wide compositional range centered on Al21.4Ni23.9Zr54.7, which is in excellent agreement with the simulations. Because the variance of cluster fractions at temperatures above the crystallization temperature is independent of quench rate as well as any particular cluster type, we believe this method could be extended to any alloy system, including those of higher complexity.Building upon this work, we examine the fundamental factors that determine the distribution and volume fraction of the crystal nucleation in simulated Al20Ni60Zr20 metallic glass/crystalline composites. The results show that the initial distribution of the atoms does not contribute to the final faction of atoms that form BCC-coordinated crystals in the composite. However, one major factor that affects the crystalline fraction is the temperature at which the stable nuclei form. The stability of Al-centered 0, 3, 6, 4 clusters also plays an important role in the final percentage of the ordered atoms.Finally, nanoindentation was performed to identify trends in hardness and indentation modulus with composition. The relationship between cluster structure and the observed mechanical behavior was evaluated by molecular dynamic simulation in Al-Ni-Zr system. By addressing the local mechanical property-cluster structure-glass forming ability relationship in this system, this study expands the understanding of the relationship of atomic structure, macroscopic mechanical behavior and glass forming ability.
Glass
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Author : Jürn W. P. Schmelzer
language : en
Publisher: Walter de Gruyter GmbH & Co KG
Release Date : 2014-05-21
Glass written by Jürn W. P. Schmelzer and has been published by Walter de Gruyter GmbH & Co KG this book supported file pdf, txt, epub, kindle and other format this book has been release on 2014-05-21 with Technology & Engineering categories.
“This book contains overviews on technologically important classes of glasses, their treatment to achieve desired properties, theoretical approaches for the description of structure-property relationships, and new concepts in the theoretical treatment of crystallization in glass-forming systems. It contains overviews about the state of the art and about specific features for the analysis and application of important classes of glass-forming systems, and describes new developments in theoretical interpretation by well-known glass scientists. Thus, the book offers comprehensive and abundant information that is difficult to come by or has not yet been made public.” Edgar Dutra Zanotto (Center for Research, Technology and Education in Vitreous Materials, Brazil) Glass, written by a team of renowned researchers and experienced book authors in the field, presents general features of glasses and glass transitions. Different classes of glassforming systems, such as silicate glasses, metallic glasses, and polymers, are exemplified. In addition, the wide field of phase formation processes and their effect on glasses and their properties is studied both from a theoretical and experimental point of view.
Dynamics Of Glassy Crystalline And Liquid Ionic Conductors
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Author : Junko Habasaki
language : en
Publisher: Springer
Release Date : 2016-10-19
Dynamics Of Glassy Crystalline And Liquid Ionic Conductors written by Junko Habasaki and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-10-19 with Science categories.
This book discusses the physics of the dynamics of ions in various ionically conducting materials, and applications including electrical energy generation and storage. The experimental techniques for measurements and characterization, molecular dynamics simulations, the theories of ion dynamics, and applications are all addressed by the authors, who are experts in their fields. The experimental techniques of measurement and characterization of dynamics of ions in glassy, crystalline, and liquid ionic conductors are introduced with the dual purpose of introducing the reader to the experimental activities of the field, and preparing the reader to understand the physical quantities derived from experiments. These experimental techniques include calorimetry, conductivity relaxation, nuclear magnetic resonance, light scattering, neutron scattering, and others. Methods of molecular dynamics simulations are introduced to teach the reader to utilize the technique for practical applications to specific problems. The results elucidate the dynamics of ions on some issues that are not accessible by experiments. The properties of ion dynamics in glassy, crystalline and liquid ionic conductors brought forth by experiments and simulations are shown to be universal, i.e. independent of physical and chemical structure of the ionic conductor as long as ion-ion interaction is the dominant factor. Moreover these universal properties of ion dynamics are shown to be isomorphic to other complex interacting systems including the large class of glass-forming materials with or without ionic conductivity.By covering the basic concepts, theories/models, experimental techniques and data, molecular dynamics simulations, and relating them together, Dynamics of Glassy, Crystalline and Liquid Ionic Conductors will be of great interest to many in basic and applied research areas from the broad and diverse communities of condensed matter physicists, chemists, materials scientists and engineers. The book also provides the fundamentals for an introduction to the field and it is written in such a way that can be used for teaching courses either at the undergraduate or graduate level in academic institutions.
Glasses And Glass Formers Current Issues Volume 455
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Author : C. A. Angell
language : en
Publisher:
Release Date : 1997-07-08
Glasses And Glass Formers Current Issues Volume 455 written by C. A. Angell and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997-07-08 with Technology & Engineering categories.
This book brings together researchers from various backgrounds dealing with the manifestations of the glassy or liquid state of matter, and with the ubiquitous characteristics of the structure and dynamic properties. The goal of this book is to compare the relative merits of different theoretical, computational and experimental approaches to the subject, and to promote the exchange of ideas between the individual disciplines. Papers reflect state-of-the-art knowledge on processes involved in glass formation, and on the relationships between structure and properties of glass-forming liquids, synthetic polymers and biopolymers. Emphasis is on novel experimental techniques, developments in computational methods, and on recent theoretical models which are improving the understanding of the observed phenomena. Topics include: short-time dynamics; relaxation dynamics of glasses and glass formers; glass-like systems, simulations and models; contrasting metallic, ionic, bio and polymer systems; structure, energetics and polyamorphism; and structure and dynamics of glasses and glass formers.
Metallic Glass Based Nanocomposites
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Author : Sumit Sharma
language : en
Publisher: CRC Press
Release Date : 2019-09-23
Metallic Glass Based Nanocomposites written by Sumit Sharma and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-09-23 with Technology & Engineering categories.
Metallic Glass-Based Nanocomposites: Molecular Dynamics Study of Properties provides readers with an overview of the most commonly used tools for MD simulation of metallic glass composites and provides all the basic steps necessary for simulating any material on Materials Studio. After reading this book, readers will be able to model their own problems on this tool for predicting the properties of metallic glass composites. This book provides an introduction to metallic glasses with definitions and classifications, provides detailed explanations of various types of composites, reinforcements and matrices, and explores the basic mechanisms of reinforcement-MG interaction during mechanical loading. It explains various models for calculating the thermal conductivity of metallic glass composites and provides examples of molecular dynamics simulations. Aimed at students and researchers, this book caters to the needs of those working in the field of molecular dynamics (MD) simulation of metallic glass composites.
Fundamentals Of Nonexponential Relaxation In Glass Forming Systems
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Author : Karan Doss
language : en
Publisher:
Release Date : 2022
Fundamentals Of Nonexponential Relaxation In Glass Forming Systems written by Karan Doss and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2022 with categories.
The remarkable complexity in the emergent behaviors exhibited by glass-forming systems have captivated physicists for the better half of the 20th century and continue to be at the forefront of condensed matter research today. Glass-forming systems are atomically disordered and relax nonexponentially when perturbed out of equilibrium. Nonexponential relaxation attracts research interest from disparate fields and has been studied across multiple levels of abstraction. The complex nature of its origins has thus far precluded the derivation of first-principles models that establish a well-defined relationship between the glass-former chemistry and corresponding macroscopic properties of interest. This has inevitably yielded numerous phenomenological models that do not stand on strong theoretical foundations. The work presented herein establishes the thermodynamic foundations of structural relaxation and elucidates the origins of heuristic mathematical models that have been successful in modeling nonexponential relaxation in glass. In this dissertation, the mean relaxation time predicted by the Maxwell relation for stress relaxation is examined. The Maxwell relation is derived within the Markov Network Model framework which is rooted in the energy landscape description of a material. An expression for the average relaxation time under equilibrium and nonequilibrium conditions are presented. It is shown that relaxation time calculated using the Maxwell relation is mismatched with the structural relaxation time. Experimental evidence is presented to show that the relaxation time obtained from shear viscosity measurements must correspond to the stress relaxation time. Subsequently, a fundamental thermodynamic description of structural relaxation in glasses is developed by establishing a link between the Prony series solution to structural relaxation derived from the principles of irreversible thermodynamics and asymmetric Lévy stable distribution of relaxation rates. Additionally, it is shown that the bulk viscosity of glass, and not the shear viscosity, is the transport coefficient that is kinetically coupled to the structural relaxation process. The distribution of relaxation times and energy barrier heights underpinning stretched exponential relaxation are derived. It is shown that a stretched exponential response necessitates the generation of a power-law or fractal distribution of relaxation times, indicating an underlying symmetry of scale-invariance in time arising from heterogeneous dynamics. The presence of large scatter in linear response data has cast doubt on the existence of an inverse correlation between liquid fragility and nonexponentiality. In this light, a model for the temperature dependence of the stretching exponent is presented based on the MYEGA model for supercooled liquid viscosity. The factors impacting the relationship between fragility and the stretching exponent at the glass transition are elucidated using this model. It is shown that the dispersion in topological degrees of freedom is proportional to the deviation from exponential behavior at the glass transition for glass formers with identical fragilities. Lastly, this dissertation lays the groundwork for disambiguating the complex dynamics of glass through the use of data-driven modeling. While molecular dynamics simulations have provided invaluable insights into the atomic-scale dynamics underpinning a broad range of glass chemistries, they offer no direct insight into the collective modes underpinning the dynamics. Dynamic Mode Decomposition, an emerging data-driven technique, is used to recover the collective modes embedded in high-dimensional time-series data obtained from molecular dynamics simulations. The recovered modes are mined to study the relationship between structure and the dynamics using pressure quenched Silica as a model system. The proposed technique is easy to implement, scalable, and easily adapted to study the relationship between glass chemistry, thermal, and pressure histories, and the underlying dynamics.
Molecular Dynamics Simulation Of The Glass Transition And The Deformation Behavior Of Amorphous Polymers
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Author : Yang-Lioe
language : en
Publisher:
Release Date : 1997
Molecular Dynamics Simulation Of The Glass Transition And The Deformation Behavior Of Amorphous Polymers written by Yang-Lioe and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with Deformations (Mechanics) categories.