scholarly journals Electret formation in transition metal oxides by electrochemical amorphization

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
Yong-Jin Kim ◽  
Chan-Ho Yang
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Charge Density ◽  
Electric Fields ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Permanent Magnets ◽  
Underlying Mechanism ◽  
Diffusion Reaction ◽  
Wide Range

AbstractTransition metal oxides (TMOs) are an important class of materials that show a wide range of functionalities involving spin, charge, and lattice degrees of freedom. The strong correlation between electrons in d-orbitals and the multivalence nature give rise to a variety of exotic electronic states ranging from insulator to superconductor and cause intriguing phase competition phenomena. Despite a burst of research on the multifarious functionalities in TMOs, little attention has been paid to the formation and integration of an electret—a type of quasi-permanent electric field generator useful for nanoscale functional devices as an electric counterpart to permanent magnets. Here, we find that an electret can be created in LaMnO3 thin films by tip-induced electric fields, with a considerable surface height change, via solid-state electrochemical amorphization. The surface charge density of the formed electret area reaches ~400 nC cm−2 and persists without significant charge reduction for more than a year. The temporal evolution of the surface height, charge density, and electric potential are systematically examined by scanning probe microscopy. The underlying mechanism is theoretically analyzed based on a drift-diffusion-reaction model, suggesting that positively charged particles, which are likely protons produced by the dissociation of water, play crucial roles as trapped charges and a catalysis to trigger amorphization. Our finding opens a new horizon for multifunctional TMOs.

Electro-forming of vacancy-doped metal-SrTiO3-metal structures

2011 ◽  
Vol 1337 ◽  
Author(s):  
Florian Hanzig ◽  
Juliane Seibt ◽  
Hartmut Stoecker ◽  
Barbara Abendroth ◽  
Dirk C. Meyer
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Physical Vapor Deposition ◽  
Oxygen Vacancies ◽  
Vacuum Annealing ◽  
Metal Insulator ◽  
Metal Structures ◽  
Wide Range ◽  
Metal Insulator Metal

ABSTRACTResistance switching in metal – insulator - metal (MIM) structures with transition metal oxides as the insulator material is a promising concept for upcoming non-volatile memories. The electronic properties of transition metal oxides can be tailored in a wide range by doping and external fields. In this study SrTiO3 single crystals are subjected to high temperature vacuum annealing. The vacuum annealing introduces oxygen vacancies, which act as donor centers. MIM stacks are produced by physical vapor deposition of Au and Ti contacts on the front and rear face of the SrTiO3 crystal. The time dependent forming of the MIM stacks under an external voltage is investigated for crystals with varying bulk conductivities. For continued formation, the resistivity increases up to failure of the system where no current can be measured anymore and switching becomes impossible.

Charge and orbital ordering in transition metal oxides

2002 ◽  
Vol 12 (9) ◽  
pp. 257-257
Author(s):  
D. Khomskii
Keyword(s):  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Relative Role ◽  
Strongly Correlated ◽  
Orbital Ordering ◽  
Spin Orbital ◽  
Electron Phonon Interaction ◽  
Frustrated Systems

Transition metal oxides with strongly correlated d-electrons show an astonishing variety of properties. This is largely determined by an interplay of different degrees of freedom: charge, spin, orbital, lattice ones. Often there appear in them various superstructures. In this talk I will consider different types of superstructures in transition metal oxides, especially charge and orbital ordering, willdiscuss the main mechanisms leading to their formation and consider specific examples of superstructures in manganites, cobaltites and in some frustrated systems. Relative role of purely electronic mechanisms and of the electron-phonon interaction will be discussed. In particular, I will show that the elastic interactions can naturally lead to different superstructures, including stripes. Special features of charge and, especially, orbital ordering in frustrated systems, where frustrations may be caused both by the geometric structure of the lattice and by the special features of orbital interactions, will be considered, and it will be shown that the order-from-disorder mechanism can lead to a unique ordered ground state in many of these cases..

scholarly journals A Lattice Litany for Transition Metal Oxides

2020 ◽  
Vol 5 (3) ◽  
pp. 46
Author(s):  
Alan R. Bishop
Keyword(s):  
Phase Transitions ◽  
Transition Metal ◽  
Metal Oxides ◽  
Excited States ◽  
Transition Metal Oxides ◽  
Degrees Of Freedom ◽  
Structural Phase ◽  
Structural Phase Transitions ◽  
Oxygen Ions ◽  
Precursor Structure

In this tribute to K Alex Müller, I describe how his early insights have influenced future decades of research on perovskite ferroelectrics and more broadly transition metal oxides (TMOs) and related quantum materials. I use his influence on my own research journey to discuss impacts in three areas: structural phase transitions, precursor structure, and quantum paraelectricity. I emphasize materials functionality in ground, metastable, and excited states arising from competitions among lattice, charge, and spin degrees of freedom, which results in highly tunable landscapes and complex networks of multiscale configurations controlling macroscopic functions. I discuss competitions between short- and long-range forces as particularly important in TMOs (and related materials classes) because of their localized and directional metal orbitals and the polarizable oxygen ions. I emphasize crucial consequences of elasticity and metal–oxygen charge transfer.

scholarly journals A Review on the Properties and Applications of WO3 Nanostructure−Based Optical and Electronic Devices

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2136
Author(s):  
Yu Yao ◽  
Dandan Sang ◽  
Liangrui Zou ◽  
Qinglin Wang ◽  
Cailong Liu
Keyword(s):  
Electrical Properties ◽  
Transition Metal ◽  
Metal Oxides ◽  
Tungsten Oxide ◽  
Transition Metal Oxides ◽  
Electronic Devices ◽  
Information Storage ◽  
High Electron ◽  
Photochromic Properties ◽  
Wide Range

Tungsten oxide (WO3) is a wide band gap semiconductor with unintentionally n−doping performance, excellent conductivity, and high electron hall mobility, which is considered as a candidate material for application in optoelectronics. Several reviews on WO3 and its derivatives for various applications dealing with electrochemical, photoelectrochemical, hybrid photocatalysts, electrochemical energy storage, and gas sensors have appeared recently. Moreover, the nanostructured transition metal oxides have attracted considerable attention in the past decade because of their unique chemical, photochromic, and physical properties leading to numerous other potential applications. Owing to their distinctive photoluminescence (PL), electrochromic and electrical properties, WO3 nanostructure−based optical and electronic devices application have attracted a wide range of research interests. This review mainly focuses on the up−to−date progress in different advanced strategies from fundamental analysis to improve WO3 optoelectric, electrochromic, and photochromic properties in the development of tungsten oxide−based advanced devices for optical and electronic applications including photodetectors, light−emitting diodes (LED), PL properties, electrical properties, and optical information storage. This review on the prior findings of WO3−related optical and electrical devices, as well as concluding remarks and forecasts will help researchers to advance the field of optoelectric applications of nanostructured transition metal oxides.

scholarly journals John Goodenough and the Many Lives of Transition-Metal Oxides

2022 ◽  
Author(s):  
John M. Tranquada
Keyword(s):  
High Temperature ◽  
Transition Metal ◽  
Metal Oxides ◽  
Transition Metal Oxides ◽  
Colossal Magnetoresistance ◽  
High Temperature Superconductivity ◽  
Mixed Valence ◽  
Wide Range ◽  
The Many

Abstract In honor of John Goodenough's centennial birthday, I discuss some of his insights into magnetism and the role of mixed valence in transition-metal oxides. His ideas form an important part of the continuing evolution of our understanding of these fascinating materials with a wide range of technologically-important functionalities. In particular, will mention connections to phenomena such as colossal magnetoresistance, enhanced thermopower, and high-temperature superconductivity.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

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