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 Composition and Temperature Effects on Aluminoborosilicate Glasses Structure and Properties written by Jingshi Wu and published by Stanford University. This book was released on 2011 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This works studies the effects of compositional and temperature variations on the structure and properties of aluminoborosilicate glasses. Two groups of aluminoborosilicate glasses, one that has lower boron content and another that has higher boron content, have been studied. The structural changes were mainly observed with high-field B-11, Al-27 and Na-23 magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. In these glasses, boron is either three-coordinate (BO3) or four-coordinate (BO4); aluminum exists predominately as four-coordinate species, but there is a small amount of five-coordinate aluminum ([5]Al). The compositional study focused on the effect of the cation field strength of the network modifiers on the glass structure by varying the ratio of the two network modifiers, CaO and Na2O. Increasing the ratio of CaO to Na2O dramatically lowers the fraction of four-coordinated boron (N4), increases [5]Al, and increases the fraction of non-bridging oxygens (NBO), which was calculated based on the boron and aluminum structural information. However, variations in these fractions are not linear with respect to the average cation field strength. Na-23 spectra reveal that the ratio of bridging to non-bridging oxygens in the coordination shell of Na+ increases with an increasing ratio of CaO to Na2O in Ca-rich glasses. These changes can be understood by the tendency of higher field strength modifier cations to facilitate the concentration of negative charges on NBO in their local coordination environment, systematically converting BO4 to BO3. The effect of temperature on the structure was studied by two ways: cooling the glass-forming melts at different rates to sample the glass structure at different fictive temperature, and using high-temperature in situ NMR. The abundances of BO3 and NBO increase with increasing fictive temperature, suggesting that the reaction BO4 [logical equivalence] BO3 + NBO shifts to the right with increasing temperature. The observed temperature dependence of the abundance of BO4 species allows us to estimate the enthalpy of reaction, [Delta]H, which is closely related to the amount of NBO in the glass. In situ high-T B-11 MAS NMR was used to observe chemical exchange between BO3 and BO4 species over the timescale of microseconds to seconds. The timescale of BO3/BO4 exchange from NMR data, [lowercase Tau](NMR), appears to be "decoupled" from that of the macroscopic shear relaxation process, [lowercase Tau](s), derived from the viscosity data; however, at higher temperatures, [lowercase Tau](s) approaches [lowercase Tau](NMR). The "decoupling" at lower temperature may be related to intermediate-range compositional heterogeneities, and /or fast modifier cation diffusivities, which trigger "unsuccessful" network exchange events.
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 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.
Download or read book Ceramic Abstracts written by and published by . This book was released on 1994 with total page 972 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Atomistic Simulations of Borosilicate Glassess written by Kuo Hao Lee and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It has been challenging to understand the cracking behavior of oxide glasses under sharp contact due to the complicated stress state in the samples and compositional dependence of the mechanical behavior of glasses. Molecular dynamics (MD) is a powerful technique to study materials structure and properties. By taking advantage of its capability of providing the time-dependent trajectories of all atoms in the system, the in-situ observation of mechanical deformation can be achieved. In this research, we used MD simulations to study the mechanical response of two commercial multi-component borosilicate glasses, Borofloat®33 (Boro33) and N-BK7® (N-BK7), under different loading conditions to obtain a more complete picture of the deformation mechanism of the indented glass from the perspective of atomic scale. This dissertation can be divided into five parts. In the first part, the performances of two sets of classical interatomic potentials for borosilicate glasses were evaluated in terms of structural and elastic properties for the two glass compositions. The results were also compared with available experimental data. It was found that the potential by Wang et al. [M. Wang, N.M. Anoop Krishnan, B. Wang, M.M. Smedskjaer, J.C. Mauro, and M. Bauchy, J. Non. Cryst. Solids, 498 294--304 (2018)] provides a closer N4 value for Boro33 but underpredicts the N4 value for N-BK7. In contrast, the N4 value of N-BK7 using the potential of Deng and Du [L. Deng and J. Du, J. Am. Ceram. Soc., 102 [5] 2482--2505 (2019)] agrees well with the experimental data, but that of Boro33 is overpredicted. Our result also indicates that Wang's potential gives a better prediction in the short-range structure, while Du's potential provides a closer medium-range structure compared with the experimental data. Neither set of potentials is able to provide accurate predictions of elastic moduli. Wang's potential predicts lower elastic modulus due to the underpredicted N4 value, whereas Du's potential yields higher elastic modulus compared with the experimental values, resulting from its overpredicted N4 value. The second part presents the results from cold compression-decompression MD simulations of the borosilicate glasses. Our results suggest that the densification of these two borosilicate glasses involves different types of structural changes. The fraction of permanent densification can be correlated to the change in intermediate-range structure. By performing Voronoi analysis, the contributions to densification from different cation types in these two multicomponent borosilicate glasses were qualified. It was found that 3-coordinated cations facilitate the densification process, and higher-coordinated cations are relatively stable and can even show a slight expansion in their Voronoi volume. The third part describes the shear behaviors of the borosilicate glasses under different pressures. It was found that the addition of alkali ions lowers the yield stress and changes the pressure dependence of shear modulus. Moreover, shear-induced densification was observed in both glasses. The results show that the decreases of the oxygen-centered bond angle and the coordination number change of B are responsible for the density changes at low pressures, and the increase of 5-coordinated Si is the dominant mechanism for densification at high pressures. The atomic shear stress was calculated the results suggest that B is able to relax mechanical stress more easily under pressurized shear compared to other element types. By analyzing the nonaffine displacement of atoms, it was found that N-BK7 exhibits more localized plastic deformation compared to Boro33 at low pressures and the local rearrangements in both glasses become more homogeneous with increasing pressure. The mean squared nonaffine displacement curves show that alkali ions have the highest mobility induced by shear compared to the network formers and B is more mobile than Si for both glasses. It was also observed that plastic deformation tends to take place around boron atoms for Boro33, whereas it occurs in the alkali-rich regions for N-BK7, indicating that these two glasses have different atomic-scale deformation mechanisms. In the fourth part, the plasticity of the two glasses under tension was investigated by implementing a uniaxial tension test using MD simulations. A bond-switching mechanism is found to be responsible for the plastic response of both glasses and is governed by the increasing rate of non-bridging oxygen (NBO) production during the uniaxial tension. It was found that the amount of B4OSi4 linkages in the glass governs the stress drop after yielding, due to its higher tendency to create NBOs compared to Si4OSi4. Also, the initial existence of NBOs weakens the critical stress for breaking the B4-O bond in B4OSi4, which in turn lowers the yield strength of the glass. The last part describes the effects of pressure on elastic properties, surface energy, and fracture toughness (K_IC) of the borosilicate glasses. It was found that the impact on K_IC is mainly dominated by the change of Young's modulus under pressure, which is proportional to the relative change in density. Between the two glasses under investigation, K_IC can be improved more effectively by the hot-compression process for Boro33, due to its higher concentration of 3-coordinated boron (B3), which facilitates densification via B3 to B4 conversion under compression.
Download or read book Physical Chemistry of Magmas written by Leonid L. Perchuk and published by Springer Science & Business Media. This book was released on 2013-04-09 with total page 351 pages. Available in PDF, EPUB and Kindle. Book excerpt: Physical Chemistry of Magmas investigates the properties, structure, and phase relationships of silicate melts with invited contributions from an international team of experts. Data and some rules for estimating the properties and structures of melts, as well as the implications of the physical chemistry of silicate liquids to igneous petrology are presented. The second section then focuses on phase relationships, with particular attention on the application of experimental and theoretical petrology to modeling the origin of certain magmas.
Download or read book Solid Oxide Fuel Cell Components written by Gurbinder Kaur and published by Springer. This book was released on 2015-12-08 with total page 421 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book examines the various interfacial reactions that take place when glass seals come into contact with components of SOFCs in reducing and oxidizing conditions. In developing an understanding of the structure and function of SOFCs, interfacial compatibility is an imperative criterion. This book addresses the technical challenges of developing sealants to avoid leakage losses at high operating temperatures, which are profoundly impactful to the efficiency of the fuel cell. This resource is important for anyone working with or studying fuel cell design and development, and is a pivotal source of cutting-edge information for research groups actively engaged in developing hermetic and stable seals which show minimum interfacial chemical reaction with interconnect and electrolyte.
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Unconventional Oxide Glass written by Ehab M. Ahmed and published by LAP Lambert Academic Publishing. This book was released on 2013 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: A special sub-set of oxide glasses is called Unconventional Oxide Glass. These oxides do not form glasses alone but can do so in binary or multicomponent mixtures with other oxides such as vanadium oxide, lead oxide, bismuth oxide and some others. The importance of such glasses is found in their interesting properties and application in switching and data storage memories. Therefore, these materials have many useful application in the field of manufacturing of many information technological systems. However, this work aimed to prepare a new unconventional transition metal oxide glass system based on both vanadium and iron oxides with the introduction of different strontium oxide concentrations. After successful preparation, some important questions appeared in mind and they have to be addressed. Such questions are: 1- Are these glasses exhibit semiconducting properties in their ac and dc electrical conductivities, or they stay in the dielectric limits?, and What is the origin of the conductivity mechanism? 2- Does these glasses exhibit a Negative Resistance phenomenon or not? 3- What are the roles and the positions in which the used cations occupy in the glass network?
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 Fundamentals of Inorganic Glasses written by Arun K. Varshneya and published by Elsevier. This book was released on 2019-05-09 with total page 753 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Inorganic Glasses, Third Edition, is a comprehensive reference on the field of glass science and engineering that covers numerous, significant advances. This new edition includes the most recent advances in glass physics and chemistry, also discussing groundbreaking applications of glassy materials. It is suitable for upper level glass science courses and professional glass scientists and engineers at industrial and government labs. Fundamental concepts, chapter-ending problem sets, an emphasis on key ideas, and timely notes on suggested readings are all included. The book provides the breadth required of a comprehensive reference, offering coverage of the composition, structure and properties of inorganic glasses. Clearly develops fundamental concepts and the basics of glass science and glass chemistry Provides a comprehensive discussion of the composition, structure and properties of inorganic glasses Features a discussion of the emerging applications of glass, including applications in energy, environment, pharmaceuticals, and more Concludes chapters with problem sets and suggested readings to facilitate self-study
Download or read book Glass Nanocomposites written by Basudeb Karmakar and published by William Andrew. This book was released on 2016-01-19 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: Glass Nanocomposites: Synthesis, Properties and Applications provides the latest information on a rapidly growing field of specialized materials, bringing light to new research findings that include a growing number of technologies and applications. With this growth, a new need for deep understanding of the synthesis methods, composite structure, processing and application of glass nanocomposites has emerged. In the book, world renowned experts in the field, Professors Karmakar, Rademann, and Stepanov, fill the knowledge gap, building a bridge between the areas of nanoscience, photonics, and glass technology. The book covers the fundamentals, synthesis, processing, material properties, structure property correlation, interpretation thereof, characterization, and a wide range of applications of glass nanocomposites in many different devices and branches of technology. Recent developments and future directions of all types of glass nanocomposites, such as metal-glasses (e.g., metal nanowire composites, nanoglass-mesoporous silica composites), semiconductor-glass and ceramic-glass nanocomposites, as well as oxide and non-oxide glasses, are also covered in great depth. Each chapter is logically structured in order to increase coherence, with each including question sets as exercises for a deeper understanding of the text. Provides comprehensive and up-to-date knowledge and literature review for both the oxide and non-oxide glass nanocomposites (i.e., practically all types of glass nanocomposites) Reviews a wide range of synthesis types, properties, characterization, and applications of diverse types of glass nanocomposites Presents future directions of glass nanocomposites for researchers and engineers, as well as question sets for use in university courses
Download or read book Engineered Materials Abstracts written by and published by . This book was released on 1989-09 with total page 536 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 Ionic Diffusion in Oxide Glasses written by Günther Heinz Frischat and published by . This book was released on 1975 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
