Core structure and mobility of Shockley partial dislocations in GaN by aberration-corrected HRTEM

2021 ◽  
Author(s):  
Isaak G. Vasileiadis ◽  
Keyword(s):  
Core Structure ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Aberration Corrected

CORE STRUCTURE OF 90° PARTIAL DISLOCATIONS IN DIAMOND

1983 ◽  
Vol 44 (C4) ◽  
pp. C4-37-C4-42 ◽  
Author(s):  
K. W. Lodge ◽  
A. Lapiccirella ◽  
N. Tomassini ◽  
S. L. Altmann
Keyword(s):  
Core Structure ◽  
Partial Dislocations

scholarly journals Evaluation of Aberration-corrected Optical Sectioning for Exploring the Core Structure of ½[111] Screw Dislocations in BCC Metals

2017 ◽  
Vol 23 (S1) ◽  
pp. 432-433
Author(s):  
D. Hernandez-Maldonado ◽  
R. Groger ◽  
Q. M. Ramasse ◽  
P. B. Hirsch ◽  
P.D. Nellist
Keyword(s):  
Core Structure ◽  
Optical Sectioning ◽  
Screw Dislocations ◽  
The Core ◽  
Bcc Metals ◽  
Aberration Corrected

Extended Defects in 4H-SiC PiN Diodes

2002 ◽  
Vol 742 ◽  
Author(s):  
M. E. Twigg ◽  
R. E. Stahlbush ◽  
M. Fatemi ◽  
S. D. Arthur ◽  
J. B. Fedison ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Compressive Strain ◽  
Pin Diode ◽  
Extended Defects ◽  
Pin Diodes ◽  
Plan View ◽  
Shockley Partial ◽  
Inhomogeneous Strain ◽  
Partial Dislocations ◽  
Transmission Electron

ABSTRACTUsing site-specific plan-view transmission electron microscopy (TEM) and lightemission imaging (LEI), we have identified SFs formed during forward biasing of 4H-SiC PiN diodes. These SFs are bounded by Shockley partial dislocations and are formed by shear strain rather than by condensation of vacancies or interstitials. Detailed analysis using TEM diffraction contrast experiments reveal SFs with leading carbon-core Shockley partial dislocations as well as with the silicon-core partial dislocations observed in plastic deformation of 4H-SiC at elevated temperatures. The leading Shockley partials are seen to relieve both tensile and compressive strain during PiN diode operation, suggesting the presence of a complex and inhomogeneous strain field in the 4H-SiC layer.

Recombination of Shockley partial dislocations by electron beam irradiation in wurtzite GaN

2019 ◽  
Vol 126 (16) ◽  
pp. 165702 ◽  
Author(s):  
I. Belabbas ◽  
I. G. Vasileiadis ◽  
J. Moneta ◽  
J. Smalc-Koziorowska ◽  
G. P. Dimitrakopulos
Keyword(s):  
Electron Beam ◽  
Electron Beam Irradiation ◽  
Beam Irradiation ◽  
Shockley Partial ◽  
Partial Dislocations

Effect of Ta on the Structure and Dynamics of γ/α2 Interfaces in Tial

1990 ◽  
Vol 213 ◽  
Author(s):  
S. R. Singh ◽  
J. M. Howe
Keyword(s):  
Partial Dislocation ◽  
Growth Mechanisms ◽  
Tial Alloys ◽  
Shockley Partial ◽  
Structure And Dynamics ◽  
Partial Dislocations ◽  
Α2 Phase ◽  
Atomically Flat ◽  
Ledge Mechanism ◽  
Image Simulations

ABSTRACTThe structure of γ/α interfaces in binary and Ta-containing TiAl alloys were analyzed by HRTEM and image simulations. Growth of α2 was found to be due to a ledge mechanism, consisting of Shockley partial dislocations on alternate (111)γ planes. The interface is atomically flat between the ledges and addition of Ta was found to transform arrays of growth ledges in the binary alloy into islands on the plate faces in the Ta-containing alloy. These islands of α2 on the γ/α2 interfaces were 4–7nm wide and increased in size with decreasing ageing temperature. The height of the ledges and islands were always a multiple of the c-parameter (0.46nm) of the α2 phase. The islands were bounded by 90°(edge) and 30° screw) Shockley partial dislocations. The 30° partial dislocation cores were localized whereas the 90° partial dislocation cores appeared to be highly delocalized due to presence of a high density of kinks, which in one case was found to be about 0.65nm−1.These results are interpreted in terms of the growth mechanisms and morphology of the α2 phase.

Atomistic simulation of fracture in Ni3Al

2008 ◽  
Vol 23 (6) ◽  
pp. 1597-1603 ◽  
Author(s):  
Hong-Xian Xie ◽  
Chong-Yu Wang ◽  
Tao Yu
Keyword(s):  
Atomistic Simulation ◽  
Crack Tip ◽  
Dislocation Core ◽  
Atomic Configuration ◽  
Close Attention ◽  
Shockley Partial ◽  
Simulation Process ◽  
Partial Dislocations ◽  
Higher Temperature ◽  
Dynamics Method

The molecular dynamics method has been used to simulate mode I cracking in Ni3Al. Close attention has been paid to the process of atomic configuration evolution of the cracks. The simulation results show that at low temperature, the Shockley partial dislocations are emitted before the initiation of the crack propagation, subsequently forming the pseudo-twins on (111) planes in crack-tip zone, and then the crack cleavage occurs. The emitting of the Shockley partial dislocations accompanies the crack cleavage during the simulation process. At the higher temperature, the blunting at the crack tip is caused by the [110] superdislocations emitted on (100) plane. The present work also shows that the dipole dislocations on (111) planes in the 1/2[110] dislocation core can be formed.

Deformation-induced α2 ↔ γ phase transformation in a Ti–48Al–2Cr alloy

2000 ◽  
Vol 15 (10) ◽  
pp. 2145-2150 ◽  
Author(s):  
J. X. Zhang ◽  
H. Q. Ye
Keyword(s):  
Electron Microscopy ◽  
Phase Transformation ◽  
Lattice Misfit ◽  
Hrem Image ◽  
Shockley Partial ◽  
Partial Dislocations ◽  
Transmission Electron ◽  
Ledge Mechanism ◽  
Related Process ◽  
Image Simulations

The structure of γ–α2 interfaces in deformed Ti–48Al–2Cr alloy was analyzed by high-resolution transmission electron microscopy (HREM) and image simulations. Growth of γ–TiAl plate in α2–Ti3Al phase was found to be a result of a ledge mechanism consisting of Shockley partial dislocations on alternate (0001)α2 planes. The height of the ledges was always a multiple of two (0001)α2 planes. The γ → α2 phase transformation was also an interface-related process. Large ledges of six close packed planes (111)γ high were often observed at the γ–α2 interface. Every large ledge consisted of six Shockley partial dislocations that originated from the γ–a2 interfacial lattice misfit. The movement of these partial dislocations accomplished the transformation of γ → α2 phase. Comparing the experimental and simulated HREM image, it was found that atomic reordering appears during the deformation-induced γ↔α2 transformation.

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