A Study of the Dependence of the Structure of Σ = 3 Tilt Boundaries in Gold on the Inclination of the Boundary Plane

1992 ◽  
Vol 278 ◽  
Author(s):  
Gui Jin Wang ◽  
V. Vitek
Keyword(s):  
Structural Unit ◽  
Atomic Level ◽  
Boundary Plane ◽  
Many Body ◽  
Chain Unit ◽  
Unit Model ◽  
Tilt Boundaries ◽  
A Chain ◽  
The Many ◽  
The Relationship

AbstractThe atomic structure of Σ = 3 tilt boundaries with variously inclined boundary planes has been studied using the many body potentials for gold. A chain unit model, analogous to the structural unit model, describes the relationship between different boundaries. The basic units in this model are units of the (111) and (112) twin boundaries and the model corresponds to atomic level faceting into these boundaries.

Investigating the Relationship Between Atomic Structure and Carrier Depletion at [001] tilt Grain Boundaries in Ybco

1999 ◽  
Vol 574 ◽  
Author(s):  
N. D. Browning ◽  
J. P. Buban
Keyword(s):  
Grain Boundaries ◽  
Structural Unit ◽  
Boundary Plane ◽  
Charge Carriers ◽  
Mobile Charge ◽  
Band Bending ◽  
Donor States ◽  
P Type ◽  
The Relationship ◽  
Theoretical Analyses

AbstractRecent theoretical analyses [1] have suggested that the origin of the reduced Jc at grain boundaries in high-Tc superconductors may be band bending, which results in the depletion of mobile charge carriers at the boundaries. For this to occur in these p-type superconductors there must, by definition, be a high density of localized donor states in the boundary plane. Here we report a “structural unit” analysis of [0011 tilt grain boundaries in YBa2Cu 3O7-δ (YBCO) that indicates there may be a simple structural origin for such localized donor states.

scholarly journals Effect of Grain Boundary Structure on Grain Boundary Diffusivities in the Au/Ag System

1990 ◽  
Vol 209 ◽  
Author(s):  
Qing Ma ◽  
R. W. Balluffi
Keyword(s):  
Thin Film ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Tilt Angle ◽  
Structural Unit ◽  
Boundary Structure ◽  
Grain Boundary Structure ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Accumulation Method

ABSTRACTGrain boundary chemical diffusivities for a series of symmetric [001] tilt boundaries in the Au/Ag system were measured by the surface accumulation method using newly developed thin-film multi-crystal specimens, in which the grain boundaries feeding the accumulation surface were all of the same type. Possible effects due to segregation at the grain boundaries and surfaces were avoided. CSL boundaries of low-Σ ( i.e., 5, 13, 17, 25) and also more general boundaries with tilt angles between the low-Σ orientations were selected. The diffusivities were found to vary monotonically with tilt angle ( i.e., no cusps at low-Σ's were found) in a manner consistent with the Structural Unit model.

On Permanent Rotations of a System of Two Coupled Gyrostats in a Central Newtonian Force Field

2015 ◽  
Author(s):  
Dmitriy Chebanov ◽  
Jose A. Salas
Keyword(s):  
Force Field ◽  
Vertical Axis ◽  
Many Body ◽  
Newtonian Force ◽  
Body Dynamics ◽  
A Chain ◽  
The Many ◽  
The One ◽  
Permanent Rotations ◽  
Newtonian Force Field

This paper studies the problem of the motion of a chain of two gyrostats coupled by an ideal spherical joint. The chain moves about a fixed point in a central Newtonian force field. Under the assumption that the gyrostatic moment of each gyrostat is constant relative to its carrier, the paper establishes and analyzes the conditions for existence of the chain’s permanent rotations about a vertical axis. For a case when each gyrostat has the mass distribution analogous to the one of a Lagrange gyroscope, the paper derives and analyzes the necessary conditions for stability of the permanent rotations. The findings of the paper extend corresponding results in the dynamics of a single gyrostat to a case of the multibody chain as well as generalize some of the known properties of permanent rotations in the many-body dynamics.

scholarly journals Detecting a many-body mobility edge with quantum quenches

2016 ◽  
Vol 1 (1) ◽  
Author(s):  
Piero Naldesi ◽  
Elisa Ercolessi ◽  
Tommaso Roscilde
Keyword(s):  
Periodic Potential ◽  
Cold Atom ◽  
Many Body ◽  
Mobility Edge ◽  
Scaling Properties ◽  
Quasi Stationary State ◽  
Quantum Quenches ◽  
A Chain ◽  
The Many ◽  
Practical Scheme

The many-body localization (MBL) transition is a quantum phase transition involving highly excited eigenstates of a disordered quantum many-body Hamiltonian, which evolve from “extended/ergodic" (exhibiting extensive entanglement entropies and fluctuations) to “localized" (exhibiting area-law scaling of entanglement and fluctuations). The MBL transition can be driven by the strength of disorder in a given spectral range, or by the energy density at fixed disorder – if the system possesses a many-body mobility edge. Here we propose to explore the latter mechanism by using “quantum-quench spectroscopy", namely via quantum quenches of variable width which prepare the state of the system in a superposition of eigenstates of the Hamiltonian within a controllable spectral region. Studying numerically a chain of interacting spinless fermions in a quasi-periodic potential, we argue that this system has a many-body mobility edge; and we show that its existence translates into a clear dynamical transition in the time evolution immediately following a quench in the strength of the quasi-periodic potential, as well as a transition in the scaling properties of the quasi-stationary state at long times. Our results suggest a practical scheme for the experimental observation of many-body mobility edges using cold-atom setups.

Atomic faceting NiSi2/Si interfaces

1994 ◽  
Vol 52 ◽  
pp. 724-725
Author(s):  
F.-R. Chen ◽  
W. J. Chen
Keyword(s):  
Thin Film ◽  
Boundary Plane ◽  
Atomic Scale ◽  
Boundary Structure ◽  
Structural Units ◽  
Long Period ◽  
Chain Unit ◽  
Unit Model ◽  
Short Period ◽  
High Resolution Tem

Sutton et al and Brokman et al suggested that long period asymmetrical boundary may facet on an atomic scale into short period symmetrical boundaries. This principle was first confirmed in the case of Σ=3 NiSi2(11)1/(15)2 and NiSi2(001)1/(21)2 asymmetrical boundaries in NiSi2 thin film by Chen et al using high resolution TEM. The asymmetrical boundaries contain a mixture of structural units of the (1)1/(11)2 and the (12)1/(12)2 symmetrical boundaries. The structural units of the (1)1/(11)2 is a 6-atom ring, while (12)1/(12)2 boundary has composite 5 and 7-atom rings. This result is consistent with the chain unit model (CUM) proposed by Wang and Vitek which describes the variation of the boundary structure with the inclination of the boundary plane.The principle of CUM was shown to be valid in the Σ=3 NiSi2(11)/(15)Si and NiSi2(21)/(001)Si asymmetrical interfaces. There are four possible atomic faceting structures for an asymmetrical interface. Fig. 1(a) shows the coexistence of two atomic faceting interfacial domains in a NiSi2(11)/(15)Si interface.

Favored Boundaries in the Structural Unit Model of Grain Boundaries

1990 ◽  
Vol 193 ◽  
Author(s):  
M. Khantha ◽  
V. Vitek ◽  
M. Goldman
Keyword(s):  
Grain Boundaries ◽  
Structural Unit ◽  
High Index ◽  
Unit Model ◽  
Tilt Boundaries ◽  
Low Symmetry

ABSTRACTA systematic geometrical procedure for predicting favored boundaries in the structural unit model is presented. The method is applicable to both symmetric and asymmetric tilt boundaries. The predictions are confirmed by modeling the structures of tilt boundaries belonging to low symmetry ( and [221]) axes in f.c.c. and b.c.c. structures. The results confirm the applicability of the structural unit model for relatively high-index tilt axes.

On the Stability of Permanent Rotations of a Chain of Two Lagrange Gyrostats in a Central Gravitational Field

2016 ◽  
Author(s):  
Dmitriy Chebanov ◽  
Jose A. Salas
Keyword(s):  
Gravitational Field ◽  
Sufficient Conditions ◽  
Vertical Axis ◽  
Many Body ◽  
A Chain ◽  
The Stability ◽  
The Many ◽  
The One ◽  
Permanent Rotations ◽  
Central Gravitational Field

In this paper we study the problem of the motion of a two-gyrostat chain about a fixed point in a central gravitational field. We assume that the mass distribution of each gyrostat is analogous to the one of a Lagrange top, the gyrostatic moment of each gyrostat is constant relative to its carrier, and the center of a spherical joint connecting the gyrostats belongs to their dynamic symmetry axes. We establish and analyze sufficient conditions for stability of the chain’s permanent rotations about a vertical axis. Our findings extend corresponding results in the dynamics of a single gyrostat to a case of the two-gyrostat chain as well as generalize some of the known properties of permanent rotations in the many-body dynamics.

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