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The investigation of the interfacial phase transitions in fluid systems with short-range intermetallic interactions are of great interest. The phenomena were studied in two systems exhibiting a liquid-liquid miscibility gap: at the fluid/wall interface in fluid KxKCl1-x and at the fluid/vacuum interface of the Ga1 xBix alloys. To characterize the interfacial changes of the ultra thin films (composition, thickness and their evolution with time) the spectroscopic ellipsometry was performed over a wide spectral range. Whereas in the experiments on KxKCl1-x an existing ellipsometer could be used, a completely new UHV-apparatus including the in-situ phase modulation ellipsometer had to be developed for Ga1 xBix alloys. For the KxKCl1-x system new results on complete wetting at solid-liquid coexistence as well as in the homogenous liquid phase (prewetting) are presented. The spectra show the typical F center absorption which indicates that the film is a salt-rich phase. The thickness strongly increases approaching the monotectic from 30 to 440 nm, which is in agreement with the tetra point wetting scenario. For this interpretation a quantitative description of the excess Gibbs energy has been developed. For the Ga1 xBix system the results on complete wetting, surface freezing and oscillatory interfacial instabilities are presented. The high-precision spectra have been recorded approaching the liquid-liquid miscibility. These spectra have been modeled using a Ga-Bi effective medium approximation for the substrate covered by a film of liquid Bi. The measurements give evidence of tetra point wetting in the Ga-Bi system. First ellipsometric study of the surface freezing in Ga-Bi has been performed. Within the miscibility gap a very interesting effect of surface and bulk oscillatory instability was observed. The details of this process at present are not well understood, but a qualitative description is given.
molten salt --- surface phase transition --- spectroscopic ellipsometry --- Ga-Bi alloys
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This book presents experimental studies of nonequilibrium phase transitions induced by ac and dc forces in collectively interacting systems—a superconducting vortex system with random pinning. It first shows that a phase transition from reversible to irreversible flow occurs by increasing vortex density as well as amplitude of ac shear, which is indicative of the universality of the reversible-irreversible transition. Two distinct flow regimes are also found in the reversible phase. Next, the book presents new methods for dc driven experiments—transverse mode-locking and transverse current-voltage measurements—and provides convincing evidence of the second-order dynamical transition from disordered plastic to anisotropically ordered smectic flow. Lastly it reports on the first experimental demonstration of the Kibble-Zurek mechanism for the nonequilibrium phase transition. The experimental results indicate that both the reversible-irreversible transition and the dynamical ordering transition belong to the directed percolation universality class which is one of the fundamental classes of nonequilibrium phase transitions. Hence, the findings will be generalized to other nonequilibrium systems and stimulate research on nonequilibrium physics.
Low temperatures. --- Condensed matter. --- Superconductivity. --- Superconductors. --- Statistical Physics. --- Low Temperature Physics. --- Phase Transition and Critical Phenomena.
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This book provides information on thermal energy storage systems incorporating phase change materials (PCMs) which are widely preferred owing to their immense energy storage capacity. The thermal energy storage (TES) potential of PCMs has been deeply explored for a wide range of applications, including solar/electrothermal energy storage, waste heat storage, and utilization, building energy-saving, and thermal regulations. The inherent shortcomings like leakage during phase transition and poor thermal conductivity hamper their extensive usage. Nevertheless, it has been addressed by their shape stabilization with porous materials and dispersing highly conductive nanoparticles. Nanoparticles suspended in traditional phase change materials enhance the thermal conductivity. The addition of these nanoparticles to the conventional PCM enhances the storage. In this book, the history of Nano Enhanced Phase Change Materials (NEPCM), preparation techniques, properties, theoretical modeling and correlations, and the effect of all these factors on the potential applications such as: solar energy, electronics cooling, heat exchangers, building, battery thermal management, thermal energy storage are discussed in detail. Future challenges and future work scope have been included. The information from this book can enable the readers to come up with novel techniques, resolve existing research limitations, and come up with novel NEPCM, that can be implemented for various applications.
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This book comprehensively presents an unconventional quantum criticality caused by valence fluctuations, which offers theoretical understanding of unconventional Fermi-liquid properties in cerium- and ytterbium-based heavy fermion metals including CeCu2(Si,Ge)2 and CeRhIn5 under pressure, and quasicrystal β-YbAlB4 and Yb15Al34Au51. The book begins with an introduction to fundamental concepts for heavy fermion systems, valence fluctuation, and quantum phase transition, including self-consistent renormalization group theory. A subsequent chapter is devoted to a comprehensive description of the theory of the unconventional quantum criticality based on a valence transition, featuring explicit temperature dependence of various physical quantities, which allows for comparisons to relevant experiments. Lastly, it discusses how ubiquitous the valence fluctuation is, presenting candidate materials not only in heavy fermions, but also in strongly correlated electrons represented by high-Tc superconductor cuprates. Introductory chapters provide useful materials for learning fundamentals of heavy fermion systems and their theory. Further, experimental topics relevant to valence fluctuations are valuable resources for those who are new to the field to easily catch up with experimental background and facts.
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This book provides a comprehensive yet concise knowledge and understanding in the field of Two-phase separation in the T-Junction. and this book can not only contribute to the academics, but it can also provide valuable insight for the industrial use of the T-junction. This book discusses in detail, the effect of different parameters on phase separation. These independent variables include diameter ratio, velocity ratio, individual phase velocities, side arm inclination, main arm inclination, mass split ratio, density of the working fluid, types of T-junctions used and modification in the T-Junction. The objectives and goals of this books are concerned with the research involved with the heat transfer applications, fluid mechanics and flow transmission in the petroleum field. Currently the data from the literature indicates that there is no specific source of consistent conclusion about the multiphase phenomenon. This book can provide a database of knowledge keeping in view of all the previous studies of the recent decades.So, engineers performing their duties in their respective sector, graduate and Ph.D students in the field of engineering can get valuable information about Two Phase Separation in the T-Junction.
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Aggregation (Chemistry) --- Clustering of particles --- Particles --- Precipitation (Chemistry) --- Clustering --- chemistry --- biology --- materials science --- aggregates --- aggregation --- Chemical Precipitation --- Precipitation, Chemical --- Phase Transition
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This book provides information on thermal energy storage systems incorporating phase change materials (PCMs) which are widely preferred owing to their immense energy storage capacity. The thermal energy storage (TES) potential of PCMs has been deeply explored for a wide range of applications, including solar/electrothermal energy storage, waste heat storage, and utilization, building energy-saving, and thermal regulations. The inherent shortcomings like leakage during phase transition and poor thermal conductivity hamper their extensive usage. Nevertheless, it has been addressed by their shape stabilization with porous materials and dispersing highly conductive nanoparticles. Nanoparticles suspended in traditional phase change materials enhance the thermal conductivity. The addition of these nanoparticles to the conventional PCM enhances the storage. In this book, the history of Nano Enhanced Phase Change Materials (NEPCM), preparation techniques, properties, theoretical modeling and correlations, and the effect of all these factors on the potential applications such as: solar energy, electronics cooling, heat exchangers, building, battery thermal management, thermal energy storage are discussed in detail. Future challenges and future work scope have been included. The information from this book can enable the readers to come up with novel techniques, resolve existing research limitations, and come up with novel NEPCM, that can be implemented for various applications.
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This thesis describes key contributions to the fundamental understanding of materials structure and dynamics from a microscopic perspective. In particular, the thesis reports several advancements in time-domain methodologies using ultrafast pulses from X-ray free-electron lasers (FEL) to probe the interactions between electrons and phonons in photoexcited materials. Using femtosecond time-resolved X-ray diffraction, the author quantifies the coherent atomic motion trajectory upon sudden excitation of carriers in SnSe. This allows the reconstruction of the nonequilibrium lattice structure and identification of a novel lattice instability towards a higher-symmetry structure not found in equilibrium. This is followed by an investigation of the excited-state phonon dispersion in SnSe using time-resolved X-ray diffuse scattering which enables important insight into how photoexcitation alters the strength of specific bonds leading to the novel lattice instability observed in X-ray diffraction. Finally, by combining ultrafast X-ray diffraction and ARPES, the author performs quantitative measurements of electron-phonon coupling in Bi2Te3 and Bi2Se3. The findings highlight the importance of time-resolved X-ray scattering techniques based on FELs, which reveals the details of interplay between electron orbitals, atomic bonds, and structural instabilities. The microscopic information of electron phonon interaction obtained from these methods can rationalize ways to control materials and to design their functional properties.
Lasers. --- Optical spectroscopy. --- Condensed matter. --- Solid state physics. --- Laser. --- Laser-Matter Interaction. --- Optical Spectroscopy. --- Structure of Condensed Matter. --- Electronic Devices. --- Phase Transition and Critical Phenomena.
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This book proposes a completely unique reaction kinetics theory based on the uncertainty principle of quantum mechanics; the physical viewpoint and mathematical details for the theory construction are explained, and abundant applications of the theory mainly in materials science are described. The theory argues that physical systems on reaction are in a quantum-mechanically uncertain state, and that such systems will transition to new states after a finite duration time. Based on this theory, if the magnitude of the energy uncertainty, i.e., energy fluctuation of the system on reaction can be determined, we can calculate the reaction rates not only for the thermal activation processes but also for the non-thermal activation process such as mechanical, optical, electromagnetic, or other actions. Therefore, researchers or engineers who are involved in fields such as the discovery of new chemical substances, development of materials, innovation of manufacturing processes, and also everyone purely interested in kinetic methodology find this book very stimulating and motivating. .
Chemical kinetics. --- Quantum chemistry. --- Condensed matter. --- Metals. --- Quantum physics. --- Reaction Kinetics. --- Quantum Chemistry. --- Phase Transition and Critical Phenomena. --- Metals and Alloys. --- Quantum Physics. --- Chemistry, Physical And Theoretical --- Condensed Matter --- Materials --- Quantum Theory --- Science --- Technology & Engineering
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This thesis addresses the design of crystal structures using hydrogen bonds. In particular, it focuses on the design of functionalities and the control over the packing of molecular assemblies, based on molecular designs. Firstly, the synthesis and evaluation of a proton–electron mixed conducting charge transfer salt is reported. Focusing on the difference in the strength of hydrogen bonds and weaker intermolecular interactions, a system was rationally designed and constructed where electron-conducting molecular wires were encapsulated within a proton-conducting matrix. Next, the investigation of structural phase transitions in a cocrystal consisting of hydrogen-bonded two-dimensional molecular assemblies is reported. Drastic rearrangements of hydrogen-bonded molecular assemblies in the cocrystal led to single-crystal-to-single-crystal phase transitions, resulting in anisotropic changes in the crystal shape. Furthermore, chemical modification of a component molecule in the cocrystal is reported. The modification afforded control over the stacking patterns of the two-dimensional molecular assemblies, i.e., sheets, and the mechanism was discussed considering the intersheet intermolecular interactions and molecular motion. It is suggested that hydrogen bonds are beneficial to construct molecular assemblies in molecular crystals because of their strength and well-defined directionality, and the consideration of coexisting weaker intermolecular interactions can lead to the design of whole crystal structures and, hence, functionalities. This thesis benefits students and researchers working on solid-state chemistry by presenting various methods for characterizing and evaluating the properties of molecular solids.
Inorganic chemistry. --- Solid state chemistry. --- Chemical bonds. --- Supramolecular chemistry. --- Materials --- Condensed matter. --- Inorganic Chemistry. --- Solid-State Chemistry. --- Chemical Bonding. --- Supramolecular Chemistry. --- Materials Characterization Technique. --- Phase Transition and Critical Phenomena. --- Analysis. --- Crystals. --- Hydrogen bonding.
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