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Über dieses Buch

Provides a summary of non-equilibrium glassy and amorphous structures and their macro- and microscopic thermal properties.

The book contains a carefully selected works of fourteen internationally recognized scientists involving the advances of the physics and chemistry of the glassy and amorphous states.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction: Some Essential Attributes of Glassiness Regarding the Nature of Non-crystalline Solids

Glass products have long been used from ancient times not only in our daily life but also in some laboratory experiments such as the U tube for the measurement of volume of a gas as a function of pressure. Liquefaction of the last “permanent gas helium” was done successfully with an apparatus entirely made of glass. Formerly the glasses have been produced by cooling the melts of silicate minerals without crystallization until they becomes hard and brittle solids. Later the glasses were found to exhibit hallo diffraction patterns similar to those of the liquids. Some important concepts are involved in this description. The first is the method of preparation. The melt-cooling was used in some of the modern definitions of glasses. The second is the starting materials of inorganic origin. Organic substances such as glycerol and synthetic polymers were found to behave similarly. Thus the term glasses can be extended to a wide range of substances that easily undercool to form amorphous solids. The third is the metastability of the undercooled liquids and glasses compared to the corresponding crystalline solids. If the cooling rate is adequately slow to induce nucleation, the melt becomes crystalline solid possessing regular lattice with lower Gibbs energy. Thus the formation of glass is a problem of bypassing or avoiding the crystallization. Although the main subjects of this book are the structures and properties of ordinary network glasses of inorganic origin, it will be instructive to start with the description of the general features of glassiness exhibited by various kinds of condensed matters in which the constituents are held together by interaction forces, such as the van der Waals, hydrogen bonding, ionic or covalent bonds.

Hiroshi Suga

Chapter 2. Heat Capacity and Entropy Functions in Strong and Fragile Glass-Formers, Relative to Those of Disordering Crystalline Materials

The glassy state problem is often separated into two major components [1, 2]. One of these concerns the reasons that glasses form in the first place, and deals with the circumstance that glasses are usually metastable with respect to crystals so that crystallization must be avoided. The second deals with the question of how liquids behave when crystals do not form, and it is with this component that we are concerned in this chapter. Here the central phenomenon with which we must deal, in seeking to understand vitrification, is the heat capacity function and the change in that function that accompanies the freezing in of the disordered state. This phenomenon is illustrated in Fig. 2.1 for a typical molecular liquid, 2-pentene vitrified by both liquid cooling and by vapor deposition [3].

C. Austen Angell

Chapter 3. Vibration Forms in the Vicinity of Glass Transition, Structural Changes and the Creation of Voids When Assuming the Role of Polarizability

Under the certain so called

critical temperature

[1], the liquid phase becomes factually prearranged and separated into solid-like structures. Certain unoccupied vacancies existing within the space are called voids (in the obvious meaning of opening, hollowness or cavity) and are packed with gas-like molecules (so called “wanderers”). This realism has been known for a long time [2]. Some of the modern structural theories (such as the so called “mode coupling theory” – MCT, which is describing the structural phenomena of liquid state at lower temperatures) are also based on a similar scheme of the local density fluctuation [3]. Such a conjecture of heterogeneities in liquid phase goes back to the assumption of semi-crystalline phase published early by Kauzman [4], as well as to the assumptions of coexistence of gas–liquid semi-structures [5,6] as related to numerous works of Cohen, Grest and Turnbull [7–10].

Jaroslav Šesták, Bořivoj Hlaváček, Pavel Hubík, Jiří J. Mareš

Chapter 4. Some Aspects of Vitrification, Amorphisation and Disordering and the Generated Extent of Nano-Crystallinity

Historically, glass is often viewed as a remarkable translucent substance though usually made from the simplest raw materials upon the effect of firing. Nature, itself, is the best instance to learn how different temperature changes can provide various glassy states, altering from very slow rates occurring within geological time scales (e.g. obsidians – glassy volcanic rocks consisting of natural acidic silicate glasses) to extremely fast, occurring as a result of fast energetically driven collapse (e.g., by impact of meteorites, yielding melted droplets then cooled to various tektites). Mimicking evolution, however, man became responsible for the creation of further families of a wide variety of glassy and amorphous materials (geopolymers), which have gradually appeared through human creativity, particularly during last 100 years. Properly chosen procedure of rapid extraction of heat (often called

quenching

) turned up to be a efficient route for successful glass-formation (

vitrification

, as a repeatable process) of almost all substances (thus allowing for the preparation of glasses from different sorts of various inorganic materials, including metals) in contrast to the traditional chemical approach, seeking just for an appropriate composition to vitrify under a customary self-cooling procedure [1,2].

Jaroslav Šesták, Carlos A. Queiroz, Jiří J. Mareš, Miroslav Holeček

Chapter 5. Basic Role of Thermal Analysis in Polymer Physics

Works in the field of calorimetry were very appreciated in the physics of the nineteenth century but for decades are not a part of physics and belong to the engineering science…

’ [1], this sentence is the most nonsensical one which has been ever written about calorimetry. One can easy find that although calorimetry is a somewhat ‘primitive’ experimental technique, it, however, is the one which does not disturb a sample physical state during the preparation process that is necessary in polymer physics. The more complicated measurement apparatus, the more the system under investigation is disturbed. Moreover, one can easy show that there is a set of experimental techniques of thermal analysis (TA), which, if applied correctly, give us a comprehensive description of the studied system under study. There are only two questions: which methods of TA and how they should be used. Certainly, it is not a problem for an experienced experimentalist who understands the basis of thermodynamics and who is able to apply the basic rules of physics in practice. It is true that some knowledge about the technical aspects of the instrument construction is required. It means that we should hardly work in our laboratories in order to improve our knowledge about the techniques used. Some incidental experiment, performed by technicians, is not sufficient for so called ‘theoreticians’ who try to involve in experimental comprehension. We will not improve any theory if we do not understand experiments and, likewise, we are unable to interpret measured parameters. There is no sense to ‘produce’ theories if they are not applicable, if they do not reflect reality. We also know that it is not easy to find an adequate theory which is confirmed totally by an experiment, especially, if we take into account ‘many-body systems’. Physics is not able to describe completely (and without approximations) systems which include more than three bodies. Therefore any theory or formula describing a polymeric system will be only a more or less good approximation reflecting a real situation occurred during an experiment.

Adam L. Danch

Chapter 6. Phases of Amorphous, Crystalline, and Intermediate Order in Microphase and Nanophase Systems

To describe matter, one can use two levels, the microscopic one, which requires identification on a molecular scale, and the macroscopic one, which can make use of the identification of the phase of the sample. The International Union of Pure and Applied Chemistry, IUPAC, has provided a binding scientific definition of the phase [1]. It is to be “an entity of a material system which is uniform in chemical composition and physical state.”

Bernhard Wunderlich

Chapter 7. Thermal Portrayal of Phase Separation in Polymers Producing Nanophase Separated Materials

Differential scanning calorimetry (DSC) and other methods of thermal analysis provide a lot of information about phase behaviour and physical properties of heterogeneous systems. This information is usually supplied by information provided by other methods, e.g., optical microscopy, X-ray and neutron diffraction, etc. Advantage of methods of thermal analysis consists in small amount of material necessary for the measurement, simple sample preparation and short measuring time.

Ivan Krakovský, Yuko Ikeda

Chapter 8. Solid Forms of Pharmaceutical Molecules

A drug discovery is characterized by two stages. The first in terms of time is called “lead structure”, followed by a so called “drug candidate” stage. The lead structure stage involves selecting the optimum molecule of the pharmaceutical, while drug candidate stage means selecting the optimum solid form. Usually, five to ten candidates pass to the drug candidate stage and the result is the selection of the final solid API (Active Pharmaceutical Ingredience) for the ensuing formulation of the solid dosage form. The lead structure stage concerns only the discovery of the original drug, the drug candidate stage may concern also generics (a drug which is bioequivalent with original and is produced and distributed after the patent protection of the original).

Bohumil Kratochvíl

Chapter 9. Chalcogenide Glasses Selected as a Model System for Studying Thermal Properties

Chalcogenide glasses have been intensively studied from the seventieth of twentieth century as the important new class of promising high-tech materials for semiconducting devices and infrared optics. Chalcogenide glasses are formed by chalcogens, stoichiometric chalcogenides, e.g. germanium and/or arsenic sulfides or selenides or by non-stoichiometrics alloys whose composition (and physicochemical properties) can be modified in broad ranges. They have unique optical properties – low phonon energies as compared with oxide glasses, high refractive index, infrared luminescence and so on. The advantage of many chalcogenide glasses is that they can be obtained using very simple technologies.

Zdeněk Černošek, Eva Černošková, Jana Holubová

Chapter 10. Viscosity Measurements Applied to Chalcogenide Glass-Forming Systems

Viscosity is an important physical parameter which determines the flow of material. The knowledge of viscous behaviour is important for example for the process of the material production. In the case of glasses and their undercooled melts, viscosity influences also the processes of structural relaxation and crystallization. Structural relaxation is in fact a very slow structural rearrangement of glass. This process can be realized through viscous flow and therefore is influenced by it. Crystallization process which may occur in undercooled melts is also influenced by the diffusion coefficient in the glassy matrix and therefore by its viscosity. This chapter tries to summarize the available viscosity data for chalcogenides and the basic measuring methods which are mostly often used to determine them.

Petr Koštál, Jana Shánělová, Jiří Málek

Chapter 11. Thermal Properties and Related Structural Study of Oxide Glasses

Glass is accompanying people from the early times of mankind. First it was the natural glass generated by the volcanic processes and the glass “produced” by the impact of meteors on the earth. During formation of the earth, highly siliceous melts of rocks froze to natural glasses such as obsidians. After some time the people start the glass melting. Glass was first produced by man about 4,000 years ago in ancient Egypt. From this time the need of the knowledge of glass composition, structure and properties is dated. These are the typical questions answered by the glass chemistry [1–6].

Marek Liška, Mária Chromčíková

Chapter 12. Oxide Glass Structure, Non-bridging Oxygen and Feasible Magnetic Properties due to the Addition of Fe/Mn Oxides

To a large extent, the physical and thermodynamic properties of glasses are controlled by their inner structural make up within the so called

short range order

(SRO) and its extended viewing as modulated structures identified as

medium range order

(MRO) [1–5] often adjacent to nano-crystalline arrangements. Study of physical nature of nano-scale in-homogeneities in glasses (and in their melts) [6, 8] provides glass inventors with basis for elaboration of glasses of a required state, from extremely homogeneous glasses (optical fibre drawing) to nano-crystallized and/or porous-containing glasses suitable for various application (sorbents, molecular filters, bioglasses, zero-expansion glass-ceramics, matrixes for nano-scale crystals, etc.). Thus structural information is essential for material scientists to predict their thermal, magnetic and other properties.

Jaroslav Šesták, Marek Liška, Pavel Hubík

Chapter 13. New Approach to Viscosity of Glasses

The most widespread assumption is that viscous flow is controlled by activation energy barrier because it changes sharply with temperature

Isak Avramov

Chapter 14. Transport Constitutive Relations, Quantum Diffusion and Periodic Reactions

In this contribution we are discussing a class of linear phenomenological transport equations and in some cases also their relation to microphysical description of corresponding effects. Interestingly enough, in spite of practically identical forms of these constitutive relations there are large differences in their physical content; just such a large diversity of natural processes behind the same mathematical form should serve as a serious warning before making superficial analogies. On the other hand, besides quite obvious analogies there may be found also those much deeper and sometimes quite astonishing. Lesser known or even new aspects of this kind the reader can find especially in paragraphs dealing with Ohm’s law and with statistical interpretation of generalized Fick’s law. The congruence of the last one with the fundamental equation of quantum mechanics, the Schrödinger equation, opened the possibility to interpret the rather enigmatic “quantum” behaviour of periodic chemical reactions as a special kind of diffusion.

Jiří J. Mareš, Jaroslav Šesták, Pavel Hubík

Chapter 15. In-Situ Investigation of the Fast Lattice Recovery during Electropulse Treatment of Heavily Cold Drawn Nanocrystalline Ni-Ti Wires

Shape memory alloys (SMA) such as the near equiatomic Ni-Ti alloy [1] have attracted considerable attention for their unique functional thermomechanical properties as superelasticity or shape memory effect deriving from the martensitic transformation. Ni-Ti wires are being produced from extruded bars by multiple hot working passes finished by a final cold drawing. In this so called “cold worked” (as-drawn, hard, etc.) state, the alloy possesses a heavily deformed microstructure resulting from severe plastic deformation [2] consisting of mixture of austenite, martensite, and amorphous phases with defects and internal strain [3].

Petr Šittner, Jan Pilch, Benoit Malard, Remi Delville, Caroline Curfs

Chapter 16. Emanation Thermal Analysis as a Method for Diffusion Structural Diagnostics of Zircon and Brannerite Minerals

Emanation thermal analysis (ETA) [1–3] based on the measurement of the radon release from samples, is one of the methods used in the diffusion structure diagnostics of solids. Changes in surface morphology and microstructure of solids during their thermal treatments and changes due to chemical, mechanical or radiation interactions can be studied by the emanation thermal analysis method.

Vladimír Balek, Iraida M. Bountseva, Igor von Beckman

Chapter 17. Scanning Transitiometry and Its Application in Petroleum Industry and in Polymer and Food Science

Liquid–solid phase equilibria in asymmetric binary mixtures are not only of general interest to explore phase equilibria in three-phase (gas, liquid, solid) systems but they play a major role in understanding and monitoring the

pT

-behaviour of petroleum fluids. Such fluids present a vast variety of compositions in terms of their respective constituents from light gases and liquids of various molecular sizes to macromolecular solids. Nowadays, the lack of thermodynamic data on asphaltenic fluids prevents the large scale exploitation of heavy oils in deep deposits. The main concern is the uncontrolled precipitation/flocculation of heavy fractions (asphaltenes, waxes) which causes obstruction and plugging of underground as well as surface installations and pipes. Research in polymer science continues to develop actively while the concepts of thermodynamics and kinetics together with polymer chain structure enhance the domain of polymer development and transformation. In many industrial applications, during extrusion processing or as all purpose materials, polymers are usually submitted to extreme conditions of temperature and pressure. Furthermore, most of the time they are also in contact with gases and fluids, either as on-duty materials (containers, pipes) or as process intermediates (foaming, molding). Since such materials are often used in special environments or under extreme conditions of temperature and pressure, their careful characterization must be done not only at the early stage of their development but also all along their life cycle. In addition, their properties as functions of temperature and pressure must be well established for the optimal control of their processability. This also stands for phase transitions; ignorance of a phase diagram, particularly at extreme conditions of pressure, temperature, and of chemical reactivity, is a limiting factor to the development of an industrial process, e.g., sol–gel transitions, polymerization under solvent near supercritical conditions, micro- and nano-foaming processes. Natural and bio-polymers constitute an important class of components largely used in food science. Among the numerous such polymers, starch serves to illustrate the complexity of state equilibria of systems containing other species like fibers, fat, proteins, and extended ranges of water percentages. In food science, industrial processing of such systems, for example during cooking extrusion, requires in depth thermodynamic as well as thermophysical characterization of the systems to process. All above fields to cite a few, in oil industry and in polymer and food applications, necessitate the acquisition of key data.

Jean-Pierre E. Grolier

Chapter 18. Constrained States Occurring in Plants Cryo-Processing and the Role of Biological Glasses

The freezing temperatures well below 0°C [1] are common and there are several mechanisms to assure life survival. Processes associated with water freezing (particularly in conjunction with its supercooling) have been intensively studied [2–4] for many years because their significance in the bionetwork of both plants [5] and living. In human activity they play an important role in various production from a plain ice making to the complex foodstuffs freezing [6, 7] and pharmacy finishing. Even more important role they play in the viability of plants in natural overwintering and in controlled cryopreservation of plants.

Jiří Zámečník, Jaroslav Šesták

Chapter 19. Thermophysical Properties of Natural Glasses at the Extremes of the Thermal History Profile

Natural amorphous glassy silicates are widely distributed and are found in quantities that range from micrograms to kilo tonnes and, hence, their occurrence is from microscopic glassy inclusions to “glassy mountains” [1]. These natural glasses have two generic origins which may be generalised as vitreous glasses, formed from the melt state by relatively rapid cooling at cooling rates that inhibit crystal formation, or diagenetic glasses, formed by a dissolution-precipitation mechanism where crystallisation is inhibited by the Ostwald's rule of stepwise petrogenesis [2]. The thermal histories of a range of natural glasses are depicted in the schematic of Fig. 19.1 and vary significantly from the typical conditions used in the glass industry which are optimised between processing speed and energy conservation. In the extremes, tektites like moldavites are formed by extremely fast heating and melting at very high temperatures (> 3,000 K) followed by quenching at extreme cooling rates (≥10 K/s). By contrast the formation of amorphous glasses from mineral diagenesis or biotic processes occurs at much lower temperatures and over longer time periods; the formation of sedimentary opal, for example, occurs at ambient temperatures, it is essentially isothermal, and takes place over long periods of time of the order of months to years.

Paul Thomas, Jaroslav Šesták, Klaus Heide, Ekkehard Füglein, Peter Šimon

Chapter 20. Hotness Manifold, Phenomenological Temperature and Other Related Concepts of Thermal Physics

Although the operative methods of temperature measurement are well-known and described in detail in various practical instructions [1, 2] and discussed in many textbooks [3–10], the systematic treatment of the central concept of thermal physics, the

temperature

itself, is paradoxically almost lacking in the current literature. The temperature, namely, is there at present defined mostly from the theoretical positions of statistical physics and not as a phenomenological quantity. Nevertheless, the predominant majority of practical measurements in physics, chemistry and technology or in thermal analysis and calorimetry particularly are performed by means of macroscopic devices (thermometers) yielding as a result the

phenomenological temperature

, and not by means of statistical analysis of properties of ensembles of particles and excitations. It is thus evident that prior to the identification of the temperature defined in the frame of statistical theory with the phenomenological temperature, the latter has to be satisfactorily defined first.

Jiří J. Mareš

Chapter 21. Historical Roots and Development of Thermal Analysis and Calorimetry

Apparently, the first person which used a thought experiment of continuous heating and cooling of an illustrative body was curiously the Czech thinker and Bohemian educator [1], latter refugee

Johann Amos Comenius

(Jan Amos Komenský, 1592–1670) when trying to envisage the properties of substances. In his “

Physicae Synopsis

”, which he finished in 1629 and published first in Leipzig in 1633, he showed the importance of hotness and coldness in all natural processes. Heat (or better fire) is considered as the cause of all motions of things. The expansion of substances and the increasing the space they occupy is caused by their dilution with heat. By the influence of cold the substance gains in density and shrinks: the condensation of vapor to liquid water is given as an example.

Comenius

also determined, though very inaccurately, the volume increase in the gas phase caused by the evaporation of a unit volume of liquid water. In Amsterdam in 1659 he published a focal but rather unfamiliar treatise on the principles of heat and cold [2], which was probably inspired by the works of the Italian philosopher

Bernardino Telesius

. The third chapter of this Comenius’ book was devoted to the description of the influence of temperature changes on the properties of substances.

Jaroslav Šesták, Pavel Hubík, Jiří J. Mareš

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