Download or read book Structural Origin of Dynamical Heterogeneities in Borosilicate Glass written by Danqi Yin and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamical heterogeneities give rise to spatiotemporal fluctuations yielding a broad distribution of relaxation rates in glass-forming systems. In order to better understand and control the relaxation process based on composition, it is essential to understand the structural origins of dynamical heterogeneities in glass-forming systems. This thesis first investigates the dominant factors governing dynamical heterogeneities in borosilicate glass. The dynamical heterogeneities of two alkali-(alumino)borosilicate glasses are investigated using the isoconfigurational ensemble method via molecular dynamics simulations. It is found that alkali ions drive high dynamical propensities in local spatial regions. The average number of bridging oxygens for both boron and silicon does not monotonically correlate with the corresponding calibrated dynamical propensity. The local alkali agglomeration affects the dynamical propensity of the alkali ion. The agglomeration of smaller alkali ions surrounding another alkali ion favors its high dynamical propensity, while the agglomeration of equal-sized or larger alkali ions favors its low dynamical propensity. The separation distance between the alkali ion and the alkali-modified boron or silicon atom affects the dynamical propensity of the alkali ion. Mixed-alkali environments perturb the relationship between the calibrated dynamical propensity of an alkali ion and its separation distance from its modified boron or its modified silicon atom. This thesis subsequently presents a theoretical framework that enables the statistical mapping of the tendency for synchronized positional rearrangements between any two structural species in the multicomponent supercooled liquid approaching the glass transition. The fundamental building blocks of the structural configuration of a multicomponent supercooled liquid are different types of structural units. Each type of structural unit is referred to as a structural species. It is established that the expected cage-breaking probability of a structural unit is proportional to the dynamical propensity of the structure calculated by the isoconfigurational ensemble method. In light of the cage-breaking probability of each structural unit, the synchronized positional rearrangements of structural units are interpreted as the simultaneous overcoming of kinetic activation barriers within a given duration. Based on this interpretation, a matrix is constructed that allows the quantitative mapping of the tendency for synchronized positional rearrangements between any two structural species in the multicomponent supercooled liquid approaching the glass transition. This established theoretical framework supports that compositional spatial heterogeneities result in dynamical heterogeneities and synchronized positional rearrangements can mitigate dynamical heterogeneities. The pairwise structural tendency of synchronized positional rearrangements for an alkali-borosilicate glass is investigated as an example. The investigated alkali-borosilicate glass has an alkali mole fraction that is greater than the mole fraction of boron, allowing for mixed network former effects, where boron speciation is energetically favored to be alkali-modified, whereas silicon speciation is entropically favored to be alkali-modified. The mapping of this alkali-borosilicate glass might imply that mixed network former effects could broaden relaxation time distributions. Considering mixed network former effects, the investigation of this alkali-borosilicate glass based on the established theoretical framework might also suggest that higher local concentrations of species that are energetically favored for alkali modification would lead to a longer regional relaxation time, however, the higher local concentrations of species that are entropically favored for alkali modification would lead to a shorter regional relaxation time.

Download or read book Dynamical Heterogeneities in Glasses Colloids and Granular Media written by Ludovic Berthier and published by OUP Oxford. This book was released on 2011-07-14 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most of the solid materials we use in everyday life, from plastics to cosmetic gels exist under a non-crystalline, amorphous form: they are glasses. Yet, we are still seeking a fundamental explanation as to what glasses really are and to why they form. In this book, we survey the most recent theoretical and experimental research dealing with glassy physics, from molecular to colloidal glasses and granular media. Leading experts in this field present broad and original perspectives on one of the deepest mysteries of condensed matter physics, with an emphasis on the key role played by heterogeneities in the dynamics of glassiness.

Download or read book Dynamical Heterogeneity in Granular Fluids and Structural Glasses written by Karina E. Avila and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Structural Glasses and Supercooled Liquids written by Peter G. Wolynes and published by John Wiley & Sons. This book was released on 2012-04-10 with total page 422 pages. Available in PDF, EPUB and Kindle. Book excerpt: With contributions from 24 global experts in diverse fields, and edited by world-recognized leaders in physical chemistry, chemical physics and biophysics, Structural Glasses and Supercooled Liquids: Theory, Experiment, and Applications presents a modern, complete survey of glassy phenomena in many systems based on firmly established characteristics of the underlying molecular motions as deduced by first principle theoretical calculations, or with direct/single-molecule experimental techniques. A well-rounded view of a variety of disordered systems where cooperative phenomena, which are epitomized by supercooled liquids, take place is provided. These systems include structural glasses and supercooled liquids, polymers, complex liquids, protein conformational dynamics, and strongly interacting electron systems with quenched/self-generated disorder. Detailed calculations and reasoned arguments closely corresponding with experimental data are included, making the book accessible to an educated non-expert reader.

Download or read book Effects of Transition Metal Oxide and Mixed Network Formers on Structure and Properties of Borosilicate Glasses written by Xiaonan Lu and published by . This book was released on 2018 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: First, the effect of transition metal oxide (e.g., V2O5, Co2O3, etc.) on the physical properties (e.g., density, glass transition temperature (Tg), optical properties and mechanical properties) and chemical durability of a simplified borosilicate nuclear waste glass was investigated. Adding V2O5 in borosilicate nuclear waste glasses decreases the Tg, while increasing the fracture toughness and chemical durability, which benefit the future formulation of nuclear waste glasses. Second, structural study of ZrO2/SiO2 substitution in silicate/borosilicate glasses was systematically conducted by molecular dynamics (MD) simulation and the quantitative structure-property relationships (QSPR) analysis to correlate structural features with measured properties. Third, for bioactive glass formulation, mixed-network former effect of B2O3 and SiO2 on the structure, as well as the physical properties and bioactivity were studied by both experiments and MD simulation. B2O3/SiO2 substitution of 45S5 and 55S5 bioactive glasses increases the glass network connectivity, correlating well with the reduction of bioactivity tested in vitro. Lastly, the effect of optical dopants on the optimum analytical performance on atom probe tomography (APT) analysis of borosilicate glasses was explored. It was found that optical doping could be an effective way to improve data quality for APT analysis with a green laser assisted system, while laser spot size is found to be critical for optimum performance. The combined experimental and simulation approach adopted in this dissertation led to a deeper understanding of complex borosilicate glass structures and structural origins of various properties.

Download or read book Encyclopedia of Glass Science Technology History and Culture Two Volume Set written by Pascal Richet and published by John Wiley & Sons. This book was released on 2021-02-05 with total page 1568 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Encyclopedia begins with an introduction summarizing itsscope and content. Glassmaking; Structure of Glass, GlassPhysics,Transport Properties, Chemistry of Glass, Glass and Light,Inorganic Glass Families, Organic Glasses, Glass and theEnvironment, Historical and Economical Aspect of Glassmaking,History of Glass, Glass and Art, and outlinepossible newdevelopments and uses as presented by the best known people in thefield (C.A. Angell, for example). Sections and chapters arearranged in a logical order to ensure overall consistency and avoiduseless repetitions. All sections are introduced by a briefintroduction and attractive illustration. Newly investigatedtopics will be addresses, with the goal of ensuring that thisEncyclopedia remains a reference work for years to come.

Download or read book Borate Glasses written by L. D. Pye and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 631 pages. Available in PDF, EPUB and Kindle. Book excerpt: Boron Oxide plays a key role in numerous glasses of high technological importance, yet its role in glass structure is far from clear. Indeed, in recent years there have been serious chal lenges to previous structure concepts for both crystalline and glassy borates. These challenges were sufficient to warrant a re examination of the structure of borate glasses using the most pow erful tools currently available. To provide a suitable forum for this undertaking, a four-day conference on "Boron in Glass and Glass Ceramics" was convened at Alfred University, June 3-8, 1977 to review the best scientific thinking on structure and to debate conflicting views and discuss properties and applications of borate glasses. This conference was also the first in a New University series on Glass Science to be rotated among Alfred University, The Pensyl vania State University, Rensselaer Polytechnic Institute, and the University of Missouri-Rolla. The present volume represents the proceedings of the first conference in this series. The volume begins with a review of the remarkable contribution of Jan Krogh-Moe to the understanding of the structure of Borate glasses. This review, authored by Professor N. J. Kreidl, concludes by dedicating the proceedings of this conference as a Krogh-Moe Fest schrift. The volume continues with a historical review by D. L. Griscom, originally prepared for circulation to the contributors prior to the conference. An Epilogue to the opening chapter brings the survey up-to-date in light of the conference papers.

Download or read book The Structural Origin of the Hard sphere Glass Transition in Granular Packing written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Glass transition is accompanied by a rapid growth of the structural relaxation time and a concomitant decrease of configurational entropy. It remains unclear whether the transition has a thermodynamic origin, and whether the dynamic arrest is associated with the growth of a certain static order. Using granular packing as a model hard-sphere glass, we show the glass transition as a thermodynamic phase transition with a 'hidden' polytetrahedral order. This polytetrahedral order is spatially correlated with the slow dynamics. It is geometrically frustrated and has a peculiar fractal dimension. Additionally, as the packing fraction increases, its growth follows an entropy-driven nucleation process, similar to that of the random first-order transition theory. In conclusion, our study essentially identifies a long-sought-after structural glass order in hard-sphere glasses.

Download or read book The Structure of Glass written by and published by . This book was released on 1966 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Structure and Crystallization of Glasses written by Werner Vogel and published by Pergamon. This book was released on 1971 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Structure and Crystallization of Glasses details glass structural analysis from an experimental perspective. The book is comprised of eight chapters that cover various structural concepts. The text first introduces the basic elements of glass structures, and then proceeds to discussing the development of classical structure theories. The next chapter presents research that deals with structure of prototype and original glasses. Next, the book details the position of the structural conceptions resulting from the studies. Chapter 5 talks about the crystallization behavior of glasses according to.

Download or read book Molecular Dynamics of Glass Forming Systems written by George Floudas and published by Springer. This book was released on 2013-01-27 with total page 176 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 1960s 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 polymers 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 Proceedings of PP1594 Topological Engineering of Ultrastrong Glasses written by Lothar Wondraczek and published by Frontiers Media SA. This book was released on 2021-02-25 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Molecular Dynamics Simulations of the Structures and Properties of Aluminosilicate and Borosilicate Glasses written by Mengguo Ren and published by . This book was released on 2018 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Structure and Mechanical Properties of Inorganic Glasses written by Georgiĭ Mikhaĭlovich Bartenev and published by . This book was released on 1970 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fluctuations in the Dynamics of Glasses written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program addressed the question of the presence of dynamical heterogeneities - strong spatial fluctuations in the dynamics - in glass forming liquids and jamming systems near dynamical arrest, with particular emphasis on aging systems, i.e. systems that are in the (non-equilibrium) glass regime. The main goals proposed for this research were: to perform numerical simulations of atomistic structural glass models to characterize dynamical heterogeneities in out of equilibrium (aging) glassy systems; to test the hypothesis that a certain symmetry (?time reparametrization symmetry?) is present in microscopic models of glassy systems and that this symmetry can explain the main features of dynamical heterogeneities; and to test to what extent these phenomena are universal across different glassy/jamming systems. It was found that: most of the important features of dynamical heterogeneities in the aging regime could be described in terms of simple scaling behaviors; that some of the most basic theoretical models of glassy systems indeed have time reparametrization symmetry; that all tests performed in numerical simulation data were consistent with the predictions from time reparametrization symmetry; and that to a large degree, the main features of dynamical heterogeneities were universal across different glassy systems. Most of the findings that came out of this research have been reported in detail in eight papers in high quality journals, two unpublished but publicly accessible manuscripts, and 27 invited and contributed talks.

Download or read book Structural Modeling of the Alkali Borosilicate Glass Systems written by Faisal M. Alamgir and published by . This book was released on 1996 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: