scholarly journals Force between two parallel screw dislocations and application to linear screw dislocation pileups—Gauge theory results

1997 ◽  
Vol 20 (4) ◽  
pp. 601-605
Author(s):  
M C Valsakumar ◽  
Debendranath Sahoo ◽  
S Kanmani
Keyword(s):  
Gauge Theory ◽  
Screw Dislocation ◽  
Screw Dislocations ◽  
Dislocation Pileups

scholarly journals The gauge theory of dislocations: a uniformly moving screw dislocation

2009 ◽  
Vol 465 (2108) ◽  
pp. 2505-2520 ◽  
Author(s):  
Markus Lazar
Keyword(s):  
Gauge Theory ◽  
Gauge Field ◽  
Screw Dislocation ◽  
Equations Of Motion ◽  
Dislocation Core ◽  
Point Of View ◽  
Theoretical Point ◽  
Theoretical Formulation ◽  
Screw Dislocations ◽  
Mach Cones

In this paper, we present the equations of motion of a moving screw dislocation in the framework of the translation gauge theory of dislocations. In the gauge field theoretical formulation, a dislocation is a massive gauge field. We calculate the gauge field theoretical solutions of a uniformly moving screw dislocation. We give the subsonic and supersonic solutions. Thus, supersonic dislocations are not forbidden from the field theoretical point of view. We show that the elastic divergences at the dislocation core are removed. We also discuss the Mach cones produced by supersonic screw dislocations.

scholarly journals Screw dislocations in the X-cube fracton model

2021 ◽  
Vol 10 (4) ◽  
Author(s):  
Nandagopal Manoj ◽  
Kevin Slagle ◽  
Wilbur Shirley ◽  
Xie Chen
Keyword(s):  
Screw Dislocation ◽  
Layered Structure ◽  
Ground State ◽  
The Other ◽  
Screw Dislocations ◽  
Topological States ◽  
Ground State Degeneracy ◽  
Induced Motion ◽  
D Model

The X-cube model, a prototypical gapped fracton model, was shown in Ref. [1] to have a foliation structure. That is, inside the 3+1 D model, there are hidden layers of 2+1 D gapped topological states. A screw dislocation in a 3+1 D lattice can often reveal nontrivial features associated with a layered structure. In this paper, we study the X-cube model on lattices with screw dislocations. In particular, we find that a screw dislocation results in a finite change in the logarithm of the ground state degeneracy of the model. Part of the change can be traced back to the effect of screw dislocations in a simple stack of 2+1 D topological states, hence corroborating the foliation structure in the model. The other part of the change comes from the induced motion of fractons or sub-dimensional excitations along the dislocation, a feature absent in the stack of 2+1D layers.

Duffin–Kemmer–Petiau oscillator in the presence of a cosmic screw dislocation

2020 ◽  
Vol 35 (30) ◽  
pp. 2050195
Author(s):  
Soroush Zare ◽  
Hassan Hassanabadi ◽  
Marc de Montigny
Keyword(s):  
Elastic Medium ◽  
Screw Dislocation ◽  
Topological Defect ◽  
Potential Functions ◽  
Wave Functions ◽  
Screw Dislocations ◽  
Energy Eigenvalues ◽  
Heun Function ◽  
Uvarov Method ◽  
The Impact

We examine the behavior of spin-zero bosons in an elastic medium which possesses a screw dislocation, which is a type of topological defect. Therefore, we solve analytically the Duffin–Kemmer–Petiau (DKP) oscillator for bosons in the presence of a screw dislocation with two types of potential functions: Cornell and linear-plus-cubic potential functions. For each of these functions, we analyze the impact of screw dislocations by determining the wave functions and the energy eigenvalues with the help of the Nikiforov–Uvarov method and Heun function.

scholarly journals Elastodynamic image forces on screw dislocations in the presence of phase boundaries

2017 ◽  
Vol 473 (2205) ◽  
pp. 20170484 ◽  
Author(s):  
Beñat Gurrutxaga-Lerma
Keyword(s):  
Screw Dislocation ◽  
Image Force ◽  
Planar Interface ◽  
Rigid Surface ◽  
Phase Boundaries ◽  
Unit Force ◽  
Screw Dislocations ◽  
Planar Phase ◽  
Explicit Formulae ◽  
Rigid Interface

The elastodynamic image forces acting on straight screw dislocations in the presence of planar phase boundaries are derived. Two separate dislocations are studied: (i) the injected, non-moving screw dislocation and (ii) the injected (or pre-existing), generally non-uniformly moving screw dislocation. The image forces are derived for both the case of a rigid surface and of a planar interface between two homogeneous, isotropic phases. The case of a rigid interface is shown to be solvable employing Head's image dislocation construction. The case of the elastodynamic image force due to an interface is solved by deriving the reflected wave's contribution to the global solution across the interface. This entails obtaining the fundamental solution (Green's function) for a point unit force via Cagniard's method, and then applying the convolution theorem for a screw dislocation modelled as a force distribution. Complete, explicit formulae are provided when available. It is shown that the elastodynamic image forces are generally affected by retardation effects, and that those acting on the moving dislocations display a dynamic magnification that exceed the attraction (or repulsion) predicted in classical elastostatic calculations.

Atomic-Scale Modeling of the Annihilation of Jogged Screw Dislocation Dipoles

1999 ◽  
Vol 578 ◽  
Author(s):  
T. Vegge ◽  
O. B. Pedersen ◽  
T. Leffers ◽  
K. W. Jacobsen
Keyword(s):  
Molecular Dynamics ◽  
Screw Dislocation ◽  
Atomic Scale ◽  
Atomistic Simulations ◽  
Elastic Band ◽  
Screw Dislocations ◽  
Scale Modeling ◽  
Band Method

AbstractUsing atomistic simulations we investigate the annihilation of screw dislocation dipoles in Cu. In particular we determine the influence of jogs on the annihilation barrier for screw dislocation dipoles. The simulations involve energy minimizations, molecular dynamics, and the Nudged Elastic Band method. We find that jogs on screw dislocations substantially reduce the annihilation barrier, hence leading to an increase in the minimum stable dipole height.

scholarly journals Confinement of Screw Dislocations to Predetermined Lateral Positions in (0001) 4H-SiC Epilayers Using Homoepitaxial Web Growth

2002 ◽  
Vol 742 ◽  
Author(s):  
Philip G. Neudeck ◽  
David J. Spry ◽  
Andrew J. Trunek ◽  
J. Anthony ◽  
Glenn M. Beheim
Keyword(s):  
Screw Dislocation ◽  
Potassium Hydroxide ◽  
Growth Process ◽  
Crystal Quality ◽  
Etch Pits ◽  
Screw Dislocations ◽  
Homoepitaxial Growth ◽  
Sic Wafer

ABSTRACTThis paper reports initial demonstration of a cantilevered homoepitaxial growth process that places screw dislocations at predetermined lateral positions in on-axis 4H-SiC mesa epilayers. Thin cantilevers were grown extending toward the interior of hollow pre-growth mesa shapes etched into an on-axis 4H-SiC wafer, eventually completely coalescing to form roofed cavities. Each completely coalesced cavity exhibited either: 1) a screw dislocation growth spiral located exactly where final cantilever coalescence occurred, or 2) no growth spiral. The fact that growth spirals are not observed at any other position except the central coalescence point suggests that substrate screw dislocations, initially surrounded by the hollow portion of the pre-growth mesa shape, are relocated to the final coalescence point of the webbed epilayer roof. Molten potassium hydroxide etch studies revealed that properly grown webbed cantilevers exhibited no etch pits, confirming the superior crystal quality of the cantilevers.

Atomistic Simulation of ½ Screw Dislocations in BCC Tungsten

2008 ◽  
Vol 59 ◽  
pp. 247-252 ◽  
Author(s):  
Jan Fikar ◽  
Robin Schäublin ◽  
Carolina Björkas
Keyword(s):  
Screw Dislocation ◽  
Atomistic Simulation ◽  
Bond Order ◽  
Analytical Approach ◽  
Atomistic Simulations ◽  
Screw Dislocations ◽  
Atom Model ◽  
Embedded Atom ◽  
Bond Order Potential

Atomistic simulations are used to describe the ½<111> screw dislocation in tungsten. Two different embedded atom model (EAM) potentials and one bond-order potential (BOP) are compared. A new analytical approach for constructing asymmetrical screw dislocations is presented.

Tem Studies of Dislocations Generated at Crack Tips

1982 ◽  
Vol 40 ◽  
pp. 472-473
Author(s):  
J. A. Horton ◽  
S. M. Ohr
Keyword(s):  
Stress Intensity ◽  
Fracture Mechanics ◽  
Screw Dislocation ◽  
Stress Intensity Factors ◽  
Dislocation Theory ◽  
Intensity Factors ◽  
Metal Fracture ◽  
Crack Tips ◽  
Dislocation Pileups ◽  
As Stress

Observations of the dislocation structure near the tips of propagating cracks are important in understanding metal fracture. Past TEM observations have shown screw dislocation pileups emitted from Mode I.II cracks. Dislocation theory has been applied to explain these observed pileups. From this analysis, fracture mechanics parameters such as stress intensity factors have been calculated.

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