Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 57
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Book Description
Density-functional theory calculations, ab-initio molecular dynamics, and the Kubo-Greenwood formula are applied to predict electrical conductivity in Ta2Ox (0 ≤ x ≤ 5) as a function of composition, phase, and temperature, where additional focus is given to various oxidation states of the O monovacancy (VOn; n=0,1+,2+). Our calculations of DC conductivity at 300K agree well with experimental measurements taken on Ta2Ox thin films and bulk Ta2O5 powder-sintered pellets, although simulation accuracy can be improved for the most insulating, stoichiometric compositions. Our conductivity calculations and further interrogation of the O-deficient Ta2O5 electronic structure provide further theoretical basis to substantiate VO0 as a donor dopant in Ta2O5 and other metal oxides. Furthermore, this dopant-like behavior appears specific to neutral VO cases in both Ta2O5 and TiO2 and was not observed in other oxidation states. This suggests that reduction and oxidation reactions may effectively act as donor activation and deactivation mechanisms, respectively, for VO0 in transition metal oxides.
Author: Andrew O'Hara
Publisher:
ISBN:
Category :
Languages : en
Pages : 444
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Book Description
Transition metal oxides have received significant attention in recent decades due to their ability to display a wide range of novel functional properties. In particular, many oxides are able to undergo metal-to-insulator transitions as a function of external stimuli such as temperature, pressure, and electric field or through doping and defect formation. In the present dissertation, density functional theory is used to explore these phenomena in three systems: (1) the Peierls transition in NbO2, (2) defect formation necessary for HfO2’s resistive switching, and (3) La-doping of SrTiO3 and trap states that may limit conductivity. For NbO2, we use successive improvements to the exchange-correlation energy combined with experiment to improve understanding of the material’s band gap in the insulating phase and show it to be close to 1.2 eV for the direct gap with an indirect gap just below 1.0 eV. Furthermore, we are able to explain the orbital contributions to the dielectric function. Using a combination of transition state theory and phonon dispersion, we demonstrate that the phase transition is driven by a second-order structural transition of the Peierls type. For HfO2, we explore the nature of the metallic gettering layer used to create substoichiometric HfO2-x for resistive switching via an atomistic model of the hafnia-hafnium interface and use transition state theory to study the ability for oxygen to diffuse across the interface. Our investigation shows that the presence of hafnium lowers the formation energy of oxygen vacancies in hafnia, but more importantly the oxidation of hafnium through oxygen migration is energetically favored. In La-doped SrTiO3, the calculations are first used to corroborate optical and electrical measurements by giving values for the density of states effective mass as well as understanding the effect of La-doping on the conductivity and DC relaxation time. Motivated by the experimental observation that even after annealing in oxygen rich environments, heavily n-type doped SrTiO3 shows carrier concentrations inconsistent with dopant concentration, we explore the role that interstitial oxygen may play as a trapping state in SrTiO3. We find three meta-stable sites and that for n-type SrTiO3, interstitials with mid-gap states are favored.
Author:
Publisher: ASM International
ISBN: 1627080996
Category :
Languages : en
Pages :
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Book Description
The International Symposium for Testing and Failure Analysis (ISTFA) 2018 is co-located with the International Test Conference (ITC) 2018, October 28 to November 1, in Phoenix, Arizona, USA at the Phoenix Convention Center. The theme for the November 2018 conference is "Failures Worth Analyzing." While technology advances fast and the market demands the latest and the greatest, successful companies strive to stay competitive and remain profitable.
Author:
Publisher: Elsevier
ISBN: 0080538312
Category : Science
Languages : en
Pages : 677
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Book Description
The book is a multi-author survey (in 15 chapters) of the current state of knowledge and recent developments in our understanding of oxide surfaces. The author list includes most of the acknowledged world experts in this field. The material covered includes fundamental theory and experimental studies of the geometrical, vibrational and electronic structure of such surfaces, but with a special emphasis on the chemical properties and associated reactivity. The main focus is on metal oxides but coverage extends from 'simple' rocksalt materials such as MgO through to complex transition metal oxides with different valencies.
Author: Chintamani Nagesa Ramachandra Rao
Publisher: VCH Publishers
ISBN:
Category : Science
Languages : en
Pages : 360
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Book Description
Author: Deepak P. Dubal
Publisher: Elsevier
ISBN: 0128104651
Category : Technology & Engineering
Languages : en
Pages : 294
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Book Description
Metal Oxides in Supercapacitors addresses the fundamentals of metal oxide-based supercapacitors and provides an overview of recent advancements in this area. Metal oxides attract most of the materials scientists use due to their excellent physico-chemical properties and stability in electrochemical systems. This justification for the usage of metal oxides as electrode materials in supercapacitors is their potential to attain high capacitance at low cost. After providing the principles, the heart of the book discusses recent advances, including: binary metal oxides-based supercapacitors, nanotechnology, ternary metal oxides, polyoxometalates and hybrids. Moreover, the factors affecting the charge storage mechanism of metal oxides are explored in detail. The electrolytes, which are the soul of supercapacitors and a mostly ignored character of investigations, are also exposed in depth, as is the fabrication and design of supercapacitors and their merits and demerits. Lastly, the market status of supercapacitors and a discussion pointing out the future scope and directions of next generation metal oxides based supercapacitors is explored, making this a comprehensive book on the latest, cutting-edge research in the field. Explores the most recent advances made in metal oxides in supercapacitors Discusses cutting-edge nanotechnology for supercapacitors Includes fundamental properties of metal oxides in supercapacitors that can be used to guide and promote technology development Contains contributions from leading international scientists active in supercapacitor research and manufacturing
Author: Per Kofstad
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 410
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Book Description
Author: H.H. Kung
Publisher: Elsevier
ISBN: 0080887422
Category : Science
Languages : en
Pages : 299
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Book Description
In this book the author presents an up-to-date summary of existing information on the structure, electronic properties, chemistry and catalytic properties of transition metal oxides. The subjects covered in the book can be divided into three sections. The first (chapters 1 to 3) covers the structural, physical, magnetic, and electronic properties of transition metal oxides. Although the emphasis is on surface properties, relevant bulk properties are also discussed. The second section (chapters 4 to 7) covers surface chemical properties. It includes topics that describe the importance of surface coordinative unsaturation in adsorption, the formation of surface acidity and the role of acidity in determining surface chemical properties, the nature and reactivities of adsorbed oxygen, and the surface chemistry in the reduction of oxides. The third section (chapters 8 to 14) is on the catalytic properties. Various catalytic reactions including decomposition, hydrogenation, isomerization, metathesis, selective oxidation, and reactions involving carbon oxides are discussed. Emphasis is placed more on reaction mechanisms and the role of catalysts than on kinetics and processes. Chapters on the preparation of oxide catalysts and on photo-assisted processes are also included. Whenever appropriate, relationships between various topics are indicated. Written for surface physicists, chemists, and catalytic engineers, the book will serve as a useful source of information for investigators and as a comprehensive overview of the subject for graduate students.
Author: Jihong Yu
Publisher: Elsevier
ISBN: 0443161410
Category : Technology & Engineering
Languages : en
Pages : 462
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Book Description
Introduction to Condensed Matter Chemistry offers a general view of chemistry from the perspective of condensed matter chemistry, analyzing and contrasting chemical reactions in a more realistic setting than traditional thinking. Readers will also find discussions on the goals and major scientific questions in condensed matter chemistry and the molecular engineering of functional condensed matter. Processes and products of chemical reactions should not be determined solely by the structure and composition of these basic species but also by the complex and possibly multilevel structured physical and chemical environment, together referred to as their condensed state. Relevant matters in condensed state should be the main bodies of chemical reactions, which is applicable not only to solids and liquids but also to gas molecules as reactions among gas molecules can take place only in the presence of catalysts in specific condensed states or after their state transition under extreme reaction conditions. This book provides new insights on the liquid state chemistry, definitions, aspects, and interactions, summarizing fundamentals of main chemical reactions from a new perspective. Helps to establish the new field of Condensed Matter Chemistry Highlights the molecular engineering of functional condensed matter Focuses on both liquid and solid state chemistry
Author: Antonio Facchetti
Publisher: John Wiley & Sons
ISBN: 9780470710593
Category : Technology & Engineering
Languages : en
Pages : 470
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Book Description
The challenge for producing “invisible” electronic circuitry and opto-electronic devices is that the transistor materials must be transparent to visible light yet have good carrier mobilities. This requires a special class of materials having “contra-indicated properties” because from the band structure point of view, the combination of transparency and conductivity is contradictory. Structured to strike a balance between introductory and advanced topics, this monograph juxtaposes fundamental science and technology / application issues, and essential materials characteristics versus device architecture and practical applications. The first section is devoted to fundamental materials compositions and their properties, including transparent conducting oxides, transparent oxide semiconductors, p-type wide-band-gap semiconductors, and single-wall carbon nanotubes. The second section deals with transparent electronic devices including thin-film transistors, photovoltaic cells, integrated electronic circuits, displays, sensors, solar cells, and electro-optic devices. Describing scientific fundamentals and recent breakthroughs such as the first “invisible” transistor, Transparent Electronics: From Synthesis to Applications brings together world renowned experts from both academia, national laboratories, and industry.
