Theory of Ionic Conduction in Solids Based on the Homogeneous Generation of Defect Pairs and Its Application to Anodic Oxidation

1971 ◽  
Vol 49 (3) ◽  
pp. 416-424 ◽  
Author(s):  
M. J. Dignam ◽  
D. F. Taylor
Keyword(s):  
Anodic Oxidation ◽  
High Field ◽  
Ionic Conduction ◽  
Three Dimensional ◽  
Alkali Halides ◽  
Mean Free Path ◽  
Homogeneous Field ◽  
Frenkel Defect ◽  
Valve Metals ◽  
Field Strengths

The theory for ionic conduction in solids based upon the homogeneous, field-assisted generation of defect pairs is developed in a general, three dimensional form, and its range of applicability is examined. At high field strengths the equations reduce to those of the so-called high field Frenkel defect theory, proposed originally by Bean, Fisher, and Vermilyea. At low field strengths, the steady-state expression reduces to the well-known conduction equation derived originally by Mott for ionic conduction in the alkali halides. At intermediate field strengths, more complicated relationships obtain. The homogeneous generation of defect pairs, whether field or current assisted, is shown to be inapplicable as a mechanism for the high field anodic oxidation of the valve metals, since either type of theory predicts unacceptable behavior for the mean free path of the mobile defects. Any such conduction mechanism can be acceptable only for the case of thick films (» 104 Å).

INVESTIGATION OF THE INFLUENCE OF SPACE CHARGE ON THE ANODIC OXIDATION OF ALUMINUM, A TYPICAL VALVE METAL

1963 ◽  
Vol 41 (12) ◽  
pp. 3108-3117 ◽  
Author(s):  
M. J. Dignam ◽  
P. J. Ryan
Keyword(s):  
Field Strength ◽  
Oxide Film ◽  
Electric Field ◽  
Electric Field Strength ◽  
Anodic Oxidation ◽  
Ionic Conduction ◽  
Time Derivative ◽  
Ionic Current ◽  
Constant Current ◽  
Frenkel Defect

Measurements of the time derivative of the anodic overpotential of superpurity aluminum during anodic oxidation were made at various constant current densities. The data have been interpreted in terms of the variation of electric field strength with position in the oxide film. The analytic form of the profile of the electric field strength in the oxide film was deduced, assuming the high field Frenkel defect model. The data were found to be incompatible with the theoretical profile, providing, therefore, evidence against this model. The data are only consistent with a model for the transport process in which the concentration of ionic current carriers at a position in the oxide remote from the metal interface is independent of the field strength. A new model, proposed recently by Dignam to explain transient ionic conduction phenomena, is consistent with this conclusion.

An Implication for Lasers of an Aspect of Interference at High Field Strengths

Nature ◽  
1964 ◽  
Vol 201 (4922) ◽  
pp. 911-912 ◽  
Author(s):  
J. A. WHITE
Keyword(s):  
High Field ◽  
Field Strengths

Thermal Design of Highly-Efficient Thermoelectric Materials With Atomic-Scale Three-Dimensional Phononic Crystals

2007 ◽  
Author(s):  
Jean-Numa Gillet ◽  
Yann Chalopin ◽  
Sebastian Volz
Keyword(s):  
Thermal Conductivity ◽  
Bulk Material ◽  
Phononic Crystal ◽  
Three Dimensional ◽  
Mean Free Path ◽  
Dispersion Curves ◽  
Phononic Crystals ◽  
Thermal Design ◽  
Atomic Scale ◽  
Thermal Insulating

Owing to their thermal insulating properties, superlattices have been extensively studied. A breakthrough in the performance of thermoelectric devices was achieved by using superlattice materials. The problem of those nanostructured materials is that they mainly affect heat transfer in only one direction. In this paper, the concept of canceling heat conduction in the three spatial directions by using atomic-scale three-dimensional (3D) phononic crystals is explored. A period of our atomic-scale 3D phononic crystal is made up of a large number of diamond-like cells of silicon atoms, which form a square supercell. At the center of each supercell, we substitute a smaller number of Si diamond-like cells by other diamond-like cells, which are composed of germanium atoms. This elementary heterostructure is periodically repeated to form a Si/Ge 3D nanostructure. To obtain different atomic configurations of the phononic crystal, the number of Ge diamond-like cells at the center of each supercell can be varied by substitution of Si diamond-like cells. The dispersion curves of those atomic configurations can be computed by lattice dynamics. With a general equation, the thermal conductivity of our atomic-scale 3D phononic crystal can be derived from the dispersion curves. The thermal conductivity can be reduced by at least one order of magnitude in an atomic-scale 3D phononic crystal compared to a bulk material. This reduction is due to the decrease of the phonon group velocities without taking into account that of the phonon average mean free path.

The connective tissue and ligaments of the distal interphalangeal joint: a review and investigation using ultra-high field 16.4 Tesla magnetic resonance imaging

2013 ◽  
Vol 39 (4) ◽  
pp. 398-404 ◽  
Author(s):  
D. Slattery ◽  
C. Aland ◽  
G. Durbridge ◽  
G. Cowin
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Connective Tissue ◽  
High Field ◽  
Three Dimensional ◽  
Interphalangeal Joint ◽  
Resonance Imaging ◽  
Distal Interphalangeal Joint ◽  
Ultra High Field ◽  
Distal Interphalangeal

This study reviews the literature on the anatomy of the connective tissues surrounding the distal interphalangeal joint and further characterizes the three-dimensional relationships of these structures with ultra-high field magnetic resonance imaging. Ten cadaver fingers, fixed in a solution of 5% agar and 4% formalin, were imaged utilising an ultrashield 16.4 Tesla ultra-high field magnetic resonance imaging, yielding a total of 4000 images. Images were analysed using Osirix™ (version 5.5.1 32 bit edition) for three-dimensional reconstruction. We found numerous conflicting descriptions of the connective tissue structures around the distal interphalangeal joint. Based upon our literature review and imaging studies we have defined precisely Cleland’s ligaments, the oblique proximal septum, Grayson’s ligaments, the dorsal plate, and the interosseous ligaments of the distal interphalangeal joint.

Intensity enhancement of attosecond XUV pulse by using asymmetric inhomogeneous mid-infrared down-chirped field

2017 ◽  
Vol 31 (26) ◽  
pp. 1750185 ◽  
Author(s):  
Liqiang Feng ◽  
Wenliang Li ◽  
Hang Liu
Keyword(s):  
Laser Intensity ◽  
Temporal Frequency ◽  
Three Dimensional ◽  
Pulse Generation ◽  
Homogeneous Field ◽  
Inhomogeneous Field ◽  
Plasmonic Enhancement ◽  
Positive Direction ◽  
Chirped Pulse ◽  
Intensity Enhancement

Intensity enhancement of the attosecond pulse generation from the high-order harmonic spectra has been theoretically investigated through solving the three-dimensional time-dependent Schrödinger equation. It is found that with the introduction of the down-chirped pulse, the temporal frequency of the down-chirp region is decreased. As a result, the ionized electrons can receive much more energy during its acceleration in this region, showing the extension of the harmonic cutoff. Moreover, due to the multi-harmonic emission events contribute to the higher harmonics, the intensity of the harmonic cutoff from the down-chirped pulse is 1.5 orders of magnitude higher than those from the chirp-free pulse. Further, by properly introducing the asymmetric inhomogeneous effect, the plasmonic enhancement of the laser intensity in the negative direction is larger than that in the positive direction. As a consequence, the ionized electron from the down-chirp region with the negative amplitude can obtain the additional acceleration, thus leading to the further extension of the harmonic cutoff. Especially when the spatial position of the inhomogeneous field is chosen to be the negative value, due to the improved enhancement of the laser intensity, not only the harmonic cutoff is extended but also the harmonic yield is near-stable, showing a 175 eV supercontinuum with the single short quantum path contribution. Finally, by directly superposing the selected harmonics, three attosecond XUV pulses with the full widths at half maximum of 38, 35 and 36 as can be obtained, which are nearly 1.5 orders of magnitude enhancement compared with the chirp-free homogeneous field case.

High Field Ionic Conduction in Anodic Ta2 O 5 Formed in Oxalic and Phosphoric Electrolytes

1985 ◽  
Vol 132 (4) ◽  
pp. 976-978 ◽  
Author(s):  
I. Montero ◽  
J. M. Albella ◽  
J. M. Martínez‐Duart
Keyword(s):  
High Field ◽  
Ionic Conduction

A modified split-ring resonator probe for NMR imaging at high field strengths

1985 ◽  
Vol 62 (3) ◽  
pp. 525-528 ◽  
Author(s):  
L.D. Hall ◽  
T. Marcus ◽  
C. Neale ◽  
B. Powell ◽  
J. Sallos ◽  
...  
Keyword(s):  
High Field ◽  
Ring Resonator ◽  
Split Ring Resonator ◽  
Nmr Imaging ◽  
Split Ring ◽  
Field Strengths

scholarly journals Reducing dielectric loss and enhancing electrical insulation for multilayer polymer films by nanoconfined ion transport under high poling electric fields

2020 ◽  
Vol 8 (18) ◽  
pp. 6102-6117 ◽  
Author(s):  
Xinyue Chen ◽  
Elshad Allahyarov ◽  
Deepak Langhe ◽  
Michael Ponting ◽  
Ruipeng Li ◽  
...  
Keyword(s):  
Electric Fields ◽  
Polymer Films ◽  
High Field ◽  
Ionic Conduction ◽  
Electric Energy ◽  
Electric Energy Storage ◽  
Conduction Loss ◽  
Impurity Ions ◽  
Energy Storage Applications ◽  
Dielectric Insulation

High-field electric poling locks impurity ions at interfaces in multilayer polymer films, which enhances dielectric insulation and reduces ionic conduction loss for electric energy storage applications.

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