Nucleation And Crystallization In Liquids And Glasses

The E-book "Nucleation and Crystallization of Glasses and Glass-Ceramics" highlights historic perspectives and current research in the field of glass-ceramic technology. Glass-ceramic technology is promising to provide us with materials of high strength, high toughness, unique electrical/electronic or magnetic properties, exceptional optical or unusual thermal or chemical properties. The greater diversity of microstructure-property arrangements and processing routes over glasses and ceramics are responsible that glass-ceramics are the preferred choice of materials in many technical, consumer, optical, medical/dental, electrical/electronic, and architectural fields. This includes increasing uses of glass-ceramic materials for environment and energy applications in the last decades. The positive development of glass-ceramic technology has become true in particular due to the pioneering spirit, resourcefulness, and courage of researchers of the first generation. Extraordinary and, therefore, to be distinguished is the work of the glass-ceramic inventor S. Donald Stookey to whom this Research Topic is dedicated. The authors, all experts in the field of glass-ceramics and based in industry, academia and governmental institutions, contributed to this E-book under the guidance of the Technical Committee 07 "Crystallization and Glass-Ceramics" of the International Commission on Glass (ICG).

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.

“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.

“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.

Crystallization is one of the most ancient and interdisciplinary topics of research known to mankind. Crystals can be organic or inorganic and may be produced from melts, liquid solutions, vapors or even in solid state. Notwithstanding its inherently high complexity, the crystallization process is part of our everyday lives, from ice making in our homes to the most state-of-the-art chemical and electronic industry. In this book, our purpose was to present new insights to the reader, as well as crucial and very useful information for researchers working in this field, while simultaneously creating a comprehensive text about crystallization processes which may serve as a starting point for people with different backgrounds.

Glasses are amorphous solids produced by cooling liquids, evaporating solutions, and condensing vapors while avoiding crystallization, with widespread applications ranging from optics to structural materials. There are many types of glasses, such as inorganic, polymeric, metallic and molecular glasses. Among them, molecular glasses have attracted increasing attention for applications in food, pharmaceutics, and organic electronics. In pharmaceutical science, molecular glasses are important for the delivery of poorly soluble drugs, because they are generally more soluble and bioavailable than their crystalline counterparts. Molecular glasses, however, readily crystallize. Therefore, a major task for developing these materials is to understand and avoid crystallization. This study concerns the stability of molecular glasses and the effect of polymer additives on this property. It is organized around four topics. The first is the role of surface mobility in the crystallization of molecular glasses. The surface diffusion of amorphous griseofulvin was measured for the first time and was found to outpace bulk diffusion by a factor of 108 at the glass transition temperature Tg. This fast surface mobility explains the fast crystal growth on free surfaces. The second topic is crystal nucleation, the first step of a crystallization process that controls many of its properties. Homogeneous nucleation rates were measured in four glass-forming molecular liquids using two methods. For the systems studied (polyalcohols), the rates of crystal nucleation span at least 10 orders of magnitude, while the rates of crystal growth are comparable at the same temperature relative to Tg. At large supercooling, the rates of nucleation and growth share a similar temperature dependence, which suggests a similar kinetic barrier for both processes. The Classical Nucleation Theory provides a reasonable description of our data, showing no sign of failure as a result of a growing length scale for corporative rearrangement in deeply cooled liquids, as recently suggested for lithium disilicate. The third topic focuses on a polymer's effect on the crystal growth and nucleation in molecular glasses. The rates of crystal growth were measured in many drug-polymer systems, and the results indicate a controlling role for the polymer's segmental mobility relative to host dynamics. The polymer effect on crystal nucleation was studied at temperatures at which the host molecules nucleate the fastest (slightly above Tg). The presence of a low-mobility polymer PVP in D-sorbitol effectively reduces the rate of crystal nucleation and the amount of reduction is similar to that seen for the growth rate. This argues that the decrease of molecular mobility by the polymer plays a controlling role. Our results, however, do not support the view that host-polymer hydrogen bonding controls the polymer's effect on crystallization. Finally, in the fourth topic, the structure of several polyalcohol liquids was studied by synchrotron total X-ray scattering to explore its relation to physical properties, such as crystallization tendency. The atomic pair-distribution functions from this work can be separated into intramolecular and intermolecular contributions to investigate the difference between the crystalline state and the liquid state in molecular structure and intermolecular hydrogen bonds. The findings of this thesis provide a better understanding of crystallization in molecular glasses and guide the selection of polymer additives to prevent the crystallization of molecular glasses.