Localized to Itinerant Electronic Transition in Perovskite Oxides PDF Download
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Author: John B. Goodenough
Publisher: Springer
ISBN: 3540455035
Category : Science
Languages : en
Pages : 249
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Book Description
Interest in the transition metal oxides with perovskite related structures goes back to the 1950s when the sodium tungsten bronzes NaxWO3 were shown to be metallic [1], the system Lal_xSr~MnO3 was found to contain a ferromagnetic conductive phase [2], and La0.sSr0.sCoO3 was reported to be a ferromagnetic metal, but with a peculiar magnetization of 1.5 #a/Co atom [3]. Stoichiometric oxide perovskites have the generic formula AMO3 in which the A site is at the center of a simple cubic array of M sites; the oxide ions form (180 ° 4)) M O M bridges to give an MO3 array of corner shared MO6/2 octahedra and the larger A cations have twelvefold oxygen coordination. Mismatch between the A O and M O equilibrium bond lengths introduces internal stresses. A compressive stress on the MO3 array is accommodated by a lowering of the M O M bond angle from 180 ° to (180 ° 4)); a tensile stress on the M O M bonds is accommodated by the formation of hexagonal polytypes [4].
Author: S.L. Cooper
Publisher: Springer Science & Business Media
ISBN: 3540675221
Category : Medical
Languages : en
Pages : 249
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Book Description
Interest in the transition metal oxides with perovskite related structures goes back to the 1950s when the sodium tungsten bronzes NaxWO3 were shown to be metallic [1 ], the system Lal_xSr MnO3 was found to contain a ferromagnetic conductive phase [2], and La0.sSr0.sCoO3 was reported to be a ferromagnetic metal, but with a peculiar magnetization of 1.5 #a/Co atom [3]. Stoichiometric oxide perovskites have the generic formula AMO3 in which the A site is at the center of a simple cubic array of M sites; the oxide ions form (180 ° 4)) M O M bridges to give an MO3 array of corner shared MO6/2 octahedra and the larger A cations have twelvefold oxygen coordination. Mismatch between the A O and M O equilibrium bond lengths introduces internal stresses. A compressive stress on the MO3 array is accommodated by a lowering of the M O M bond angle from 180 ° to (180 ° 4)); a tensile stress on the M O M bonds is accommodated by the formation of hexagonal polytypes [4].
Author: John B. Goodenough
Publisher:
ISBN: 9783662146620
Category :
Languages : en
Pages : 256
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Book Description
Author: John B. Goodenough
Publisher: Springer
ISBN: 9783540455035
Category : Science
Languages : en
Pages : 239
Get Book Here
Book Description
Author: John B. Goodenough
Publisher: Springer
ISBN: 3540455035
Category : Science
Languages : en
Pages : 249
Get Book Here
Book Description
Interest in the transition metal oxides with perovskite related structures goes back to the 1950s when the sodium tungsten bronzes NaxWO3 were shown to be metallic [1], the system Lal_xSr~MnO3 was found to contain a ferromagnetic conductive phase [2], and La0.sSr0.sCoO3 was reported to be a ferromagnetic metal, but with a peculiar magnetization of 1.5 #a/Co atom [3]. Stoichiometric oxide perovskites have the generic formula AMO3 in which the A site is at the center of a simple cubic array of M sites; the oxide ions form (180 ° 4)) M O M bridges to give an MO3 array of corner shared MO6/2 octahedra and the larger A cations have twelvefold oxygen coordination. Mismatch between the A O and M O equilibrium bond lengths introduces internal stresses. A compressive stress on the MO3 array is accommodated by a lowering of the M O M bond angle from 180 ° to (180 ° 4)); a tensile stress on the M O M bonds is accommodated by the formation of hexagonal polytypes [4].
Author: Franklin Wong
Publisher:
ISBN:
Category :
Languages : en
Pages : 312
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Book Description
The focus of this dissertation is on tuning electronic phase transitions in perovskite oxide heterostructures. The recurring theme is the exploitation of characteristics inherent to heteroepitaxy that are unavailable in the bulk materials of identical chemistry; these inherent characteristics are epitaxial strain and interfacial electronic reconstruction. In contrast, the effects of chemical substitution, for example, are not defining traits of heterostructures as they can be routinely studied in bulk materials, and therefore will not be included in this work. Heteroepitaxial lattice deformation is identified to be crucial in two systems: coherently strained LaTiO3 films on SrTiO3 substrates and La2/3Sr1/3MnO3 films on LaAlO3 substrates. One the other hand, interfacial charge transfer is the responsible for the insulator-metal transitions in LaAlO3 films on SrTiO3 substrates, or LaAlO3/SrTiO3 heterointerfaces. The charge, orbital, spin, and lattice "degrees of freedom" are intimately linked in perovskite oxides, particularly those containing transition metals. The lattice can be modified through heteroepitaxial strain, and the charge state can be modified through interfacial electronic reconstruction. It is shown that epitaxial strain can induce an insulator-metal transition in LaTiO3, which is a Mott insulator in the bulk that is near an electronic instability owing to its orbital disorder. It is confirmed that metallic conduction occurs throughout the entire thicknesses of the LaTiO3 films, as opposed to being confined to the surfaces or interfaces. It is possible to exploit heteroepitaxial strain as a knob to modulate the electronic bandwidth. Strain values that can be introduced routinely in thin films are greater than those which are easily accessible in hydrostatic or uniaxial stress studies of bulk materials. Epitaxial strain also is explicitly linked to the enhanced magnetoresistive properties of La2/3Sr1/3MnO3 films, particularly at low temperatures. The key effect appears to be the stabilization of a more insulating phase that may coexist with the double-exchange metallic ferromagnetic phase, which is stable in the bulk. The more insulating phase in turn becomes unstable upon the application of a magnetic field, resulting in higher magnetoresistance over a wide range of temperatures. While such a mechanism is certainly believed to be pertinent for many bulk manganites, it is not expected to be relevant for the specific chemical composition studied. Similar to the case of LaTiO3, the orbital degrees of freedom in La2/3Sr1/3MnO3 are important for the tunability of such an electronic transition controlled by thin-film lattice deformation; an added ingredient is that there exist two competing magnetic exchange mechanisms that are sensitive to chemical bonding. Both the orbital degree of freedom and competing exchange interactions make the electronic properties of manganite films very sensitive to external lattice perturbations. Finally, metallic LaAlO & euro;3/SrTiO3 heterointerfaces between two nominally undoped insulators are examined. Interfacial polarity is believed to induce electron transfer from LaAlO3 to SrTiO3. Low temperature magnetotransport studies reveal signatures of strong spin-orbit interaction in this quasi-two-dimensional metallic channel. The spin-orbit coupling in the heterostructures is enhanced greatly by interfacial electric fields; hence, it represents a property that is fundamentally non-bulk-like. The transport data presented in this work suggest that disorder and carriers are introduced concurrently at the heterointerface, and also shed light on the origin of metallicity.
Author: Karl A. Mller
Publisher: World Scientific
ISBN: 9814293350
Category : Science
Languages : en
Pages : 583
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Book Description
In this book some 50 papers published by K A Mller as author or co-author over a period from 1959 till 2009, amplified by more recent work mainly by T W Kool with collaborators are reproduced. The main subject is Electron Paramagnetic Resonance (EPR) applied to the study of perovskites and other oxides with related subjects. This wealth of papers is organized into eleven chapters, each with an introductory text written in the light of current understanding. The contributions of the first author on structural phase transitions have been immense, and because K A Mller and J C Fayet have published a review paper on the subject, the latter is reproduced in chapter VII. Exceptions is here I have omitted the half sentence on chapter VI, it is EPR related whole chapter VIII on dipolar and quantum paraelectric behavior with dielectric studies. Further in chapter X two papers proving the existence of Fermi-Glasses are reproduced. The year 1986 bears some significance: early in this year the paper by Bednorz and Mller on the possible observation of superconductivity was published. This resulted in a substantial shift in the paradigm of condensed matter physics to which the present first author has scientifically with those that of others in a second volume.
Author: Pascal Granger
Publisher: John Wiley & Sons
ISBN: 3527686592
Category : Technology & Engineering
Languages : en
Pages : 1056
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Book Description
This comprehensive handbook and ready reference details all the main achievements in the field of perovskite-based and related mixed-oxide materials. The authors discuss, in an unbiased manner, the potentials as well as the challenges related to their use, thus offering new perspectives for research and development on both an academic and industrial level. The first volume begins by summarizing the different synthesis routes from molten salts at high temperatures to colloidal crystal template methods, before going on to focus on the physical properties of the resulting materials and their related applications in the fields of electronics, energy harvesting, and storage as well as electromechanics and superconductivity. The second volume is dedicated to the catalytic applications of perovskites and related mixed oxides, including, but not limited to total oxidation of hydrocarbons, dry reforming of methane and denitrogenation. The concluding section deals with the development of chemical reactors and novel perovskite-based applications, such as fuel cells and high-performance ceramic membranes. Throughout, the contributions clearly point out the intimate links between structure, properties and applications of these materials, making this an invaluable tool for materials scientists and for catalytic and physical chemists.
Author: Gibin George
Publisher: CRC Press
ISBN: 1000195686
Category : Science
Languages : en
Pages : 385
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Book Description
This textbook entitled Fundamentals of Perovskite Oxides: Synthesis, Structure, Properties and Applications summarizes the structure, synthesis routes, and potential applications of perovskite oxide materials. Since these perovskite-type ceramic materials offer opportunities in a wide range of fields of science and engineering, the chapters are broadly organized into four sections of perovskite-type oxide materials and technology. Covers recent developments in perovskite oxides Serves as a quick reference of perovskite oxides information Describes novel synthesis routes for nanostructured perovskites Discusses comprehensive details for various crystal structures, synthesis methods, properties, and applications Applies to academic education, scientific research, and industrial R&D for materials research in real-world applications like bioengineering, catalysis, energy conversion, energy storage, environmental engineering, and data storage and sensing This book serves as a handy and practical guideline suitable for students, engineers, and researchers working with advanced ceramic materials.
Author: Alexander Leonidovich Kuzemsky
Publisher: World Scientific
ISBN: 981314565X
Category : Science
Languages : en
Pages : 1259
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Book Description
The book is devoted to the study of the correlation effects in many-particle systems. It presents the advanced methods of quantum statistical mechanics (equilibrium and nonequilibrium), and shows their effectiveness and operational ability in applications to problems of quantum solid-state theory, quantum theory of magnetism and the kinetic theory. The book includes description of the fundamental concepts and techniques of analysis following the approach of N N Bogoliubov's school, including recent developments. It provides an overview that introduces the main notions of quantum many-particle physics with the emphasis on concepts and models.This book combines the features of textbook and research monograph. For many topics the aim is to start from the beginning and to guide the reader to the threshold of advanced researches. Many chapters include also additional information and discuss many complex research areas which are not often discussed in other places. The book is useful for established researchers to organize and present the advanced material disseminated in the literature. The book contains also an extensive bibliography.The book serves undergraduate, graduate and postgraduate students, as well as researchers who have had prior experience with the subject matter at a more elementary level or have used other many-particle techniques.
Author: Hidetoshi Fukuyama
Publisher: Springer Science & Business Media
ISBN: 3642600417
Category : Science
Languages : en
Pages : 351
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Book Description
Physics and Chemistry of Transition-Metal Oxides includes both theoretical and experimental approaches to the variety of phenomena found in the transition-metal oxides, including high-temperature superconductivity, colossal magnetoresistance, and metal-insulator transition. These are the central issues in materials science and condensed matter physics/chemistry, and readers can obtain up-to-date information on what is happening in this field of research.
