Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
Get Book Here
Book Description
Perovskite manganites are complex systems in which the structural, electronic, and magnetic properties are strongly coupled - in many cases, non-linearly. A small change in one property (e.g., structure) can produce a large change in other properties (e.g., the electronic state). Conceptually, creating a surface by cleaving a single crystal or growing a thin film provides a controlled way to disturb the coupled system by breaking the symmetry without changing the stoichiometry, which may lead to completely new physical properties. The emerging surface electronic phases can be further enriched by surface reconstructions which often occur due to bond breaking at the surface and also by extrinsic carrier doping from adsorbates as well. While the cleaving method is limited to a small amount of cleavable layered materials, the thin-film growth method, such as laser molecular beam epitaxy (Laser MBE), becomes the most desired technique for the study of surfaces in general. As an example, La1-[subscript x]Ca[subscript x]MnO3, which is one of the most investigated cubic perovskite manganite systems, has a surface that cannot be created by cleaving the bulk but can be prepared by laser MBE. In this dissertation, La1-[subscript x]Ca[subscript x]MnO2 (001) (x = 3/8) thin films grown by laser MBE were studied with a combination of in-situ techniques such as low-energy electron diffraction (LEED) and high-resolution scanning probe microscopy (SPM). Two different electronic conductivities were observed using scanning tunneling spectroscopy (STS) on the thin-film surface. The "atomic" resolution scanning tunneling microscopy (STM) images revealed that the two different conductivities come from two reconstructed surfaces, (1 x 1) and ([square root]2 x [square root]2)R45°, respectively. The (1 x 1) and ([square root]2 x [square root]2)R45° reconstructions were found to be reversible by oxygen adsorption/desorption, and as a result, the conductivity of the surface can be tuned from metallic to insulating by controlling the oxygen adsorption. Further investigations revealed the existence of a surface structure transition driven by the film thickness. The (1 x 1) surface without oxygen adsorption actually has specific superstructures; it changes from c(2 x 4) to (3[square root]2 x 4[square root]2)R45° with a critical thickness of 14 ML associated with an extensive strain induced by the substrate. The discoveries of the unexpected surface structural and electronic transitions revealed in this dissertation open up a new direction for exploring the functionality relationship at the surfaces of complex transition-metal compound thin films.
Author: Gertjan Koster
Publisher: Woodhead Publishing
ISBN: 0081029462
Category : Science
Languages : en
Pages : 534
Get Book Here
Book Description
Epitaxial Growth of Complex Metal Oxides, Second Edition reviews techniques and recent developments in the fabrication quality of complex metal oxides, which are facilitating advances in electronic, magnetic and optical applications. Sections review the key techniques involved in the epitaxial growth of complex metal oxides and explore the effects of strain and stoichiometry on crystal structure and related properties in thin film oxides. Finally, the book concludes by discussing selected examples of important applications of complex metal oxide thin films, including optoelectronics, batteries, spintronics and neuromorphic applications. This new edition has been fully updated, with brand new chapters on topics such as atomic layer deposition, interfaces, STEM-EELs, and the epitaxial growth of multiferroics, ferroelectrics and nanocomposites. - Examines the techniques used in epitaxial thin film growth for complex oxides, including atomic layer deposition, sputtering techniques, molecular beam epitaxy, and chemical solution deposition techniques - Reviews materials design strategies and materials property analysis methods, including the impacts of defects, strain, interfaces and stoichiometry - Describes key applications of epitaxially grown metal oxides, including optoelectronics, batteries, spintronics and neuromorphic applications
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
Get Book Here
Book Description
The trend to reduce device dimensions demands increasing attention to atomic-scale details of structure of thin films as well as to pathways to control it. We found that this is of special importance in the systems with multiple competing interactions. We have used in situ scanning tunneling microscopy to image surfaces of La5/8Ca3/8MnO3 films grown by pulsed laser deposition. The atomically resolved imaging was combined with in situ angle-resolved X-ray photoelectron spectroscopy. We find a strong effect of the background oxygen pressure during deposition on structural and chemical features of the film surface. Deposition at 50 mTorr of O2 leads to mixed-terminated film surfaces, with B-site (MnO2) termination being structurally imperfect at the atomic scale. Moreover, a relatively small reduction of the oxygen pressure to 20 mTorr results in a dramatic change of the surface structure leading to a nearly perfectly ordered B-site terminated surface with only a small fraction of A-site (La, Ca)O termination. This is accompanied, however, by surface roughening at a mesoscopic length scale. The results suggest that oxygen has a strong link to the adatom mobility during growth. The effect of the oxygen pressure on dopant surface segregation is also pronounced: Ca surface segregation is decreased with oxygen pressure reduction.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
Get Book Here
Book Description
The doped manganese oxides (manganites) have been widely studied for their colossal magnetoresistive effects, for potential applications in oxide spintronics, electroforming in resistive switching devices, and are materials of choice as cathodes in modern solid oxide fuel cells. However, little experimental knowledge of the dynamics of the surfaces of perovskite manganites at the atomic scale exists. Here, through in-situ scanning tunnelling microscopy (STM), we demonstrate atomic resolution on samples of La0.625Ca0.375MnO3 grown on (001) SrTiO3 by pulsed laser deposition (PLD). Furthermore, by applying triangular DC waveforms of increasing amplitude to the STM tip, and measuring the tunnelling current, we demonstrate the ability to both perform and monitor surface electrochemical processes at the atomic level, including, for the first time in a manganite, formation of single and multiple oxygen vacancies, disruption of the overlying manganite layers, and removal and deposition of individual atomic units or clusters. Our work paves the way for better understanding of surface oxygen reactions in these systems.
Author: Ōsaka Daigaku. Sangyō Kagaku Kenkyūjo
Publisher:
ISBN:
Category : Research
Languages : en
Pages : 404
Get Book Here
Book Description
Author:
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 2540
Get Book Here
Book Description
Author: Joseph Woicik
Publisher: Springer
ISBN: 3319240439
Category : Science
Languages : en
Pages : 576
Get Book Here
Book Description
This book provides the first complete and up-to-date summary of the state of the art in HAXPES and motivates readers to harness its powerful capabilities in their own research. The chapters are written by experts. They include historical work, modern instrumentation, theory and applications. This book spans from physics to chemistry and materials science and engineering. In consideration of the rapid development of the technique, several chapters include highlights illustrating future opportunities as well.
Author: Asim K. Ray
Publisher: John Wiley & Sons
ISBN: 1119529476
Category : Technology & Engineering
Languages : en
Pages : 628
Get Book Here
Book Description
Oxide Electronics Multiple disciplines converge in this insightful exploration of complex metal oxides and their functions and properties Oxide Electronics delivers a broad and comprehensive exploration of complex metal oxides designed to meet the multidisciplinary needs of electrical and electronic engineers, physicists, and material scientists. The distinguished author eschews complex mathematics whenever possible and focuses on the physical and functional properties of metal oxides in each chapter. Each of the sixteen chapters featured within the book begins with an abstract and an introduction to the topic, clear explanations are presented with graphical illustrations and relevant equations throughout the book. Numerous supporting references are included, and each chapter is self-contained, making them perfect for use both as a reference and as study material. Readers will learn how and why the field of oxide electronics is a key area of research and exploitation in materials science, electrical engineering, and semiconductor physics. The book encompasses every application area where the functional and electronic properties of various genres of oxides are exploited. Readers will also learn from topics like: Thorough discussions of High-k gate oxide for silicon heterostructure MOSFET devices and semiconductor-dielectric interfaces An exploration of printable high-mobility transparent amorphous oxide semiconductors Treatments of graphene oxide electronics, magnetic oxides, ferroelectric oxides, and materials for spin electronics Examinations of the calcium aluminate binary compound, perovoksites for photovoltaics, and oxide 2Degs Analyses of various applications for oxide electronics, including data storage, microprocessors, biomedical devices, LCDs, photovoltaic cells, TFTs, and sensors Suitable for researchers in semiconductor technology or working in materials science, electrical engineering, and physics, Oxide Electronics will also earn a place in the libraries of private industry researchers like device engineers working on electronic applications of oxide electronics. Engineers working on photovoltaics, sensors, or consumer electronics will also benefit from this book.
Author: Gurbinder Kaur
Publisher: Elsevier
ISBN: 0128174463
Category : Technology & Engineering
Languages : en
Pages : 516
Get Book Here
Book Description
Intermediate Temperature Solid Oxide Fuel Cells: Electrolytes, Electrodes and Interconnects introduces the fundamental principles of intermediate solid oxide fuel cells technology. It provides the reader with a broad understanding and practical knowledge of the electrodes, pyrochlore/perovskite/oxide electrolytes and interconnects which form the backbone of the Solid Oxide Fuel Cell (SOFC) unit. Opening with an introduction to the thermodynamics, physiochemical and electrochemical behavior of Solid Oxide Fuel Cells (SOFC), the book also discusses specific materials, including low temperature brownmillerites and aurivillius electrolytes, as well as pyrochlore interconnects. This book analyzes the basic concepts, providing cutting-edge information for both researchers and students. It is a complete reference for Intermediate Solid Oxide Fuel Cells technology that will be a vital resource for those working in materials science, fuel cells and solid state chemistry. - Provides a single source of information on glass, electrolytes, interconnects, vanadates, pyrochlores and perovskite SOFC - Includes illustrations that provide a clear visual explanation of concepts being discussed - Progresses from a discussion of basic concepts that will enable readers to easily comprehend the subject matter
Author: Stephen J. Pennycook
Publisher: Springer Science & Business Media
ISBN: 1441972005
Category : Technology & Engineering
Languages : en
Pages : 764
Get Book Here
Book Description
Scanning transmission electron microscopy has become a mainstream technique for imaging and analysis at atomic resolution and sensitivity, and the authors of this book are widely credited with bringing the field to its present popularity. Scanning Transmission Electron Microscopy(STEM): Imaging and Analysis will provide a comprehensive explanation of the theory and practice of STEM from introductory to advanced levels, covering the instrument, image formation and scattering theory, and definition and measurement of resolution for both imaging and analysis. The authors will present examples of the use of combined imaging and spectroscopy for solving materials problems in a variety of fields, including condensed matter physics, materials science, catalysis, biology, and nanoscience. Therefore this will be a comprehensive reference for those working in applied fields wishing to use the technique, for graduate students learning microscopy for the first time, and for specialists in other fields of microscopy.
