screw dislocations
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2022 ◽  
pp. 108128652110728
Author(s):  
Ping Yang ◽  
Xu Wang ◽  
Peter Schiavone

The method of continuously distributed dislocations is used to study the distribution of screw dislocations in a linear array piled up near the interface of a two-phase isotropic elastic thin film with equal thickness in each phase. The resulting singular integral equation is solved numerically using the Gauss–Chebyshev integration formula to arrive at the dislocation distribution function and the number of dislocations in the pileup.


2022 ◽  
Vol 223 ◽  
pp. 117398
Author(s):  
Émile Maras ◽  
Emmanuel Clouet

Author(s):  
С.А. Кукушкин ◽  
А.В. Осипов ◽  
А.В. Редьков ◽  
В.М. Стожаров ◽  
Е.В. Убыйвовк ◽  
...  

The growth of InGaN layers on hybrid SiC/Si substrates with orientations (100), (110), and (111) by the HVPE method was studied at temperatures that wittingly exceed the temperature of InN decomposition onto nitrogen atoms and metallic In (1000C). On substrates with orientations (110) and (111), the formation of InGaN nanocrystals was observed. The shape and growth mechanisms of nanocrystals were investigated. It is shown that nanocrystals nucleate on the (111) surface only inside V-defects formed at the points where screw dislocations exit onto the surface. On the (110) surface, nanocrystals are formed only on pedestals that arise during the film growth. An explanation is given for the difference in the growth mechanisms of nanocrystals on substrates of different orientations.


Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5890
Author(s):  
Hejing Wang ◽  
Jinying Yu ◽  
Guojie Hu ◽  
Yan Peng ◽  
Xuejian Xie ◽  
...  

Micropipe, a “killer” defect in SiC crystals, severely hampers the outstanding performance of SiC-based devices. In this paper, the etching behavior of micropipes in 4H-SiC and 6H-SiC wafers was studied using the molten KOH etching method. The spectra of 4H-SiC and 6H-SiC crystals containing micropipes were examined using Raman scattering. A new Raman peak accompanying micropipes located near −784 cm−1 was observed, which may have been induced by polymorphic transformation during the etching process in the area of micropipe etch pits. This feature may provide a new way to distinguish micropipes from other defects. In addition, the preferable etching conditions for distinguishing micropipes from threading screw dislocations (TSDs) was determined using laser confocal microscopy, scanning electron microscopy (SEM) and optical microscopy. Meanwhile, the micropipe etching pits were classified into two types based on their morphology and formation mechanism.


2021 ◽  
Vol 104 (11) ◽  
Author(s):  
Hongying Wang ◽  
Yajuan Cheng ◽  
Masahiro Nomura ◽  
Sebastian Volz ◽  
Davide Donadio ◽  
...  

Carbon Trends ◽  
2021 ◽  
pp. 100106
Author(s):  
Filippo S. Boi ◽  
Shanling Wang ◽  
Wenxue Li ◽  
Omololu Odunmbaku ◽  
Shuai Gao ◽  
...  

2021 ◽  
Vol 3 ◽  
pp. 100014
Author(s):  
Abu Bakar Siddique ◽  
Tariq A. Khraishi

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sheng Yin ◽  
Yunxing Zuo ◽  
Anas Abu-Odeh ◽  
Hui Zheng ◽  
Xiang-Guo Li ◽  
...  

AbstractRefractory high-entropy alloys (RHEAs) are designed for high elevated-temperature strength, with both edge and screw dislocations playing an important role for plastic deformation. However, they can also display a significant energetic driving force for chemical short-range ordering (SRO). Here, we investigate mechanisms underlying the mobilities of screw and edge dislocations in the body-centered cubic MoNbTaW RHEA over a wide temperature range using extensive molecular dynamics simulations based on a highly-accurate machine-learning interatomic potential. Further, we specifically evaluate how these mechanisms are affected by the presence of SRO. The mobility of edge dislocations is found to be enhanced by the presence of SRO, whereas the rate of double-kink nucleation in the motion of screw dislocations is reduced, although this influence of SRO appears to be attenuated at increasing temperature. Independent of the presence of SRO, a cross-slip locking mechanism is observed for the motion of screws, which provides for extra strengthening for refractory high-entropy alloy system.


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