Download or read book Inflection Point in Pressure Dependent Molecular Dynamics of Various Glass forming Liquids written by Erik Thoms and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Dynamics of Glass Forming Systems written by George Floudas and published by Springer Science & Business Media. This book was released on 2010-11-25 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Study of the Dynamics of Glass Forming Liquids Using Molecular Dynamics Simulations written by Christopher Henry Sokolowski and published by . This book was released on 2010 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Molecular Dynamics Simulation Study of Dynamic Processes in Molecular Glass Forming Liquids written by Patrick Henritzi and published by . This book was released on 2014 with total page 191 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Complex Dynamics of Glass Forming Liquids written by Wolfgang Götze and published by Oxford University Press on Demand. This book was released on 2009 with total page 654 pages. Available in PDF, EPUB and Kindle. Book excerpt: Amorphous condensed matter can exhibit complex motions on time scales which extend up to those relevant for the functioning of biomaterials. The book presents the derivation of a microscopic theory for amorphous matter, which exhibits the evolution of such complex motions as a new paradigm of strongly interacting particle systems.e

Download or read book Molecular Dynamics and Relaxation Phenomena in Glasses written by Thomas Dorfmüller and published by . This book was released on 1987 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the proceedings of a workshop on glass-forming liquids held at the University of Bielefeld in 1985. The aim of the meeting was to seek unifying interpretations which may apply to all glass-forming materials like inorganic and polymer glasses. Also, new data was presented and modern interpretations were applied which represent the state-of-the-art knowledge about the unusual physical properties of these chemically-diverse glass-forming materials. The book should be of interest to specialists in the subject, to polymer scientists, glass technologists and materials scientists, but also - and most importantly - to researchers and teachers who wish to become informed on some of the most recent fundamental research in the fields.

Download or read book Molecular Cooperativity in the Dynamics of Glass forming Materials written by Liang Hong and published by . This book was released on 2010 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Although glass has been fabricated for thousands of years, the microscopic mechanism governing the glass transition process remains unclear. The main challenge is to understand the non-Arrhenius temperature dependence of the structural relaxation time of the supercooled liquids upon approaching the glass transition temperature. Most researchers ascribe it to cooperative molecular motions. Various experimental results and simulations show that the structural relaxation of a supercooled liquid is spatially heterogeneous. This dynamic heterogeneity is usually attributed to the cooperative molecular motions in local domains. The cooperativity size is estimated from the spatial heterogeneity to be ~1-4 nanometers. However, many important questions are still unsolved, e.g. what is the role of molecular cooperativity in the temperature dependence of the structural relaxation time? On the other hand, the collective vibration in the GHz-THz frequency range, the so-called boson peak, is also considered to be a manifestation of a cooperative process with a characteristic length scale of a few nanometers. Some researchers even speculate that the length scale associated with the boson peak is related to the cooperativity length scale of the main structural relaxation. In this dissertation, we estimated the characteristic length scale from the boson peak spectra measured using light scattering for a large number of glass-forming materials. By comparing it to the dynamic heterogeneity length scale of the main structural relaxation acquired via 4-dimensional NMR, we find that the collective vibrations and the structural relaxation involve a similar length scale of molecular cooperativity. When a supercooled liquid is cooled down to the glass transition temperature, decreases in free volume and thermal energy both contribute to slowing down the structural relaxation. Our analysis demonstrates that only the volume contribution to the variation of the structural relaxation time has a direct correlation with the cooperativity size among different materials, whereas the thermal energy contribution does not. The latter is more dependent on the chemical structure of the studied materials. These results call for a conceptually new approach to the analysis of the mechanism of the glass transition and to the role of molecular cooperativity."--Abstract.

Download or read book A Molecular Dynamics Study of the Structure dynamics Relationships of Supercooled Liquids and Glasses written by Ryan Soklaski and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Central to the field of condensed matter physics is a decades old outstanding problem in the study of glasses -- namely explaining the extreme slowing of dynamics in a liquid as it is supercooled towards the so-called glass transition. Efforts to universally describe the stretched relaxation processes and heterogeneous dynamics that characteristically develop in supercooled liquids remain divided in both their approaches and successes. Towards this end, a consensus on the role that atomic and molecular structures play in the liquid is even more tenuous. However, mounting material science research efforts have culminated to reveal that the vast diversity of metallic glass species and their properties are rooted in an equally-broad set of structural archetypes. Herein lies the motivation of this dissertation: the detailed information available regarding the structure-property relationships of metallic glasses provides a new context in which one can study the evolution of a supercooled liquid by utilizing a structural motif that is known to dominate the glass. Cu_64 Zr_36 is a binary alloy whose good glass-forming ability and simple composition makes it a canonical material to both empirical and numerical studies. Here, we perform classical molecular dynamics simulations and conduct a comprehensive analysis of the dynamical regimes of liquid Cu_64 Zr_36, while focusing on the roles played by atomic icosahedral ordering -- a structural motif which ultimately percolates the glass' structure. Large data analysis techniques are leveraged to obtain uniquely detailed structural and dynamical information in this context. In doing so, we develop the first account of the origin of icosahedral order in this alloy, revealing deep connections between this incipient structural ordering, frustration-limited domain theory, and recent important empirical findings that are relevant to the nature of metallic liquids at large. Furthermore, important dynamical landmarks such as the breakdown of the Stokes-Einstein relationship, the decoupling of particle diffusivities, and the development of general "glassy" relaxation features are found to coincide with successive manifestation of icosahedral ordering that arise as the liquid is supercooled. Remarkably, we detect critical-like features in the growth of the icosahedron network, with signatures that suggest that a liquid-liquid phase transition may occur in the deeply supercooled regime to precede glass formation. Such a transition is predicted to occur in many supercooled liquids, although explicit evidence of this phenomenon in realistic systems is scarce. Ultimately this work concludes that icosahedral order characterizes all dynamical regimes of Cu_64 Zr_36, demonstrating the importance and utility of studying supercooled liquids in the context of locally-preferred structure. More broadly, it serves to confirm and inform recent theoretical and empirical findings that are central to understanding the physics underlying the glass transition

Download or read book Dynamical Correlations in Glassforming Liquids written by Elise R. Aaron and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glass transitions appear across physical systems of widely varying types. Molecular liquids, polymers, and colloids have all demonstrated transition to an amorphous glassy solid when subjected to rapid cooling or compression. These materials appear frequently in nature and are useful in numerous industrial applications, including the window glass we are familiar with and many materials in the category of plastics. The macroscopic behaviors of these systems have been well documented and leveraged, but we still lack a full picture of the microscopic origins of those behaviors. Such a picture, besides its conceptual appeal, would provide a more robust framework for materials engineering, and methods developed along the way will be applicable to studies of other emergent phenomena. We thus want to investigate the physics underlying the glass transition. Specifically, we would like to quantify the dynamic heterogeneity that experiments and simulations have indicated is present. Dynamic heterogeneity refers to the presence of distinct spatial regions with collectively fast or slow dynamics, which exist at different places in the system and change over time. These heterogeneities are thought to influence the slowdown and “freezing” of the system into a glassy state. I focus here on quantifying the lifetime of the heterogeneous regions. I perform analysis on data from numerical simulations of several different systems, including a new set of molecular dynamics simulations of a Lennard-Jones variant system, at densities and temperatures approaching their glass transitions. I begin by quantifying bulk properties of each system as a function of the simulation timescale. I then compute a correlation function that comes out of previously developed theory, which provides a measure of the persistence of the heterogeneity as a function of the timescale. I observe how long that function takes to decay, and compare my results with previous attempts at measuring this quantity via other methods, which have generally given much larger results. Some interesting observations come out of these measurements, such as the presence of a time delay in the correlation signal and a constant “background” signal in my correlation measurement. Future work could improve the measurements by identifying the source of this background and estimating measurement uncertainties.

Download or read book Structure Thermophysical Properties of Liquids and Their Connection with Glass Formability written by Rongrong Dai and published by . This book was released on 2020 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic glasses have drawn significant attention due to their unique properties, such as high strength, excellent elastic energy storage capacity, and versatile processability. However, why some liquids can easily form metallic glasses while others don't is still unclear. Since metallic glasses are formed when liquids are cooled fast enough to bypass crystallization, we hope to better understand glass formation by investigating the structural evolution and thermophysical properties of the liquids as they are cooled toward the glass transition. Multiple molecular dynamics simulations suggest a crossover temperature for the dynamics near the liquidus temperature, which corresponds to the onset of cooperative structural rearrangements and may be the beginning of the glass transition. In this dissertation, a possible structural signature of this onset of cooperativity is first identified using high-energy synchrotron X-ray scattering studies and viscosity measurements on electrostatically levitated liquids. We also address the practical question of how to predict glass formation from properties of the high temperature liquids. A method to accurately predict the glass transition temperature in metallic glasses from properties of the equilibrium liquids is proposed. It uses the viscosity and the thermal expansion coefficient for the equilibrium liquid. Using the predicted glass transition temperature and a fragility parameter developed from the liquid properties, a new prediction formula is generated, which only uses the liquid properties. While the prediction formula works for most cases, in some cases, it fails. The analysis of these anomalous cases demonstrates that the structural similarity between the liquid and crystal phases plays an important role in the glass formability. This is the first demonstration of this important controlling factor for glass formability. We also used machine learning (Lasso regression and Random Forest) to predict the glass formability and identify important predictors. The identified important predictors are in good agreement with those from the empirical rules. Finally, the evolution of the Cu46Zr54 liquid structure is investigated by elastic neutron scattering (with isotopic substitution) and synchrotron X-ray scattering studies. The experimental results show that the number of Cu-Cu and Zr-Zr atom pairs increases as the temperature decreases, while the number of Cu-Zr atom pairs decreases on cooling. This result disagrees with predictions from previous molecular dynamics studies, suggesting that the potentials used in the molecular dynamics simulations should be reassessed.

Download or read book Nonequilibrium Molecular Dynamics written by Billy D. Todd and published by Cambridge University Press. This book was released on 2017-03-10 with total page 371 pages. Available in PDF, EPUB and Kindle. Book excerpt: This coherent collection of theory, algorithms, and illustrative results presents the field of nonequilibrium molecular dynamics in detail.

Download or read book Density Dependence of Rotational and Translational Molecular Dynamics in Liquids Studied by High Pressure NMR written by E. W. Lang and published by . This book was released on 1993 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Modern Glass Characterization written by Mario Affatigato and published by John Wiley & Sons. This book was released on 2015-10-05 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book consists of a series of edited chapters, each written by an expert in the field and focusing on a particular characterization technique as applied to glass. The book covers a variety of techniques ranging from the very common (like Raman and FTIR) to the most recent (and less well known) ones, like SEM for structural analysis and photoelastic measurements. The level of the chapters make it suitable for researchers and for graduate students about to start their research work. It will also: discuss the technique itself, background, nuances when it comes to looking at glassy materials, interpretation of results, case studies, and recent and near-future innovations Fill a widening gap in modern techniques for glass characterization Provide much needed updates on the multiple essential characterization techniques

Download or read book Advances in Chemical Physics Volume 161 written by Stuart A. Rice and published by John Wiley & Sons. This book was released on 2016-08-29 with total page 574 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Advances in Chemical Physics series provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline. • This is the only series of volumes available that presents the cutting edge of research in chemical physics. • Includes contributions from experts in this field of research. • Contains a representative cross-section of research that questions established thinking on chemical solutions • Structured with an editorial framework that makes the book an excellent supplement to an advanced graduate class in physical chemistry or chemical physics

Download or read book Encyclopedia of Polymer Blends Volume 3 written by Avraam I. Isayev and published by John Wiley & Sons. This book was released on 2016-06-07 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: A complete and timely overview of the topic, this Encyclopedia imparts knowledge of fundamental principles and their applications for academicians, scientists and researchers, while informing engineers, industrialists and entrepreneurs of the current state of the technology and its utilization. The most comprehensive source on polymer blends available on the market Offers a complete and timely overview of the topic Each article presents up to date research & development on a topic and its basic principles and applications, integrates case studies, laboratory and pilot plant experiments, and gives due reference to published and patented literature Equips academics, scientists and researchers with knowledge of fundamentals principles and their applications, and informs the engineers, industrialists and entrepreneurs about the state of the art technology and its applications

Download or read book The Glass Transition written by E. Donth and published by Springer Science & Business Media. This book was released on 2013-04-17 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes and interrelates the following processes: cooperative alpha processes in a cold liquid, structural relaxation in the glass near Tg, the Johari-Goldstein beta process, the Williams-Götze process in a warm liquid, fast nonactivated cage rattling and boson peak, and ultraslow Fischer modes.

Download or read book Introduction to Glass Science and Technology written by James E Shelby and published by Royal Society of Chemistry. This book was released on 2015-11-06 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a concise and inexpensive introduction for an undergraduate course in glass science and technology. The level of the book has deliberately been maintained at the introductory level to avoid confusion of the student by inclusion of more advanced material, and is unique in that its text is limited to the amount suitable for a one term course for students in materials science, ceramics or inorganic chemistry. The contents cover the fundamental topics of importance in glass science and technology, including glass formation, crystallization, phase separation and structure of glasses. Additional chapters discuss the most important properties of glasses, including discussion of physical, optical, electrical, chemical and mechanical properties. A final chapter provides an introduction to a number of methods used to form technical glasses, including glass sheet, bottles, insulation fibre, optical fibres and other common commercial products. In addition, the book contains discussion of the effects of phase separation and crystallization on the properties of glasses, which is neglected in other texts. Although intended primarily as a textbook, Introduction to Glass Science and Technology will also be invaluable to the engineer or scientist who desires more knowledge regarding the formation, properties and production of glass.