Evidence from Moiré Patterns of Packing Faults in Boron Nitride Crystals

Nature ◽  
1957 ◽  
Vol 180 (4583) ◽  
pp. 425-427 ◽  
Author(s):  
J. F. GOODMAN
2021 ◽  
Vol 24 (1) ◽  
pp. 13701
Author(s):  
W.S. Wu-Mei ◽  
R.R. Rey-González

In this article, we report the electronic band structures of hexagonal bilayer systems, specifically, rotated graphene-graphene and boron nitride-boron nitride bilayers, by introducing an angle between the layers and forming new periodic structures, known as moiré patterns. Using a semi-empirical tight-binding approach with a parametrized hopping parameter between the layers, using one orbital per-site approximation, and taking into account nearest-neighbor interactions only, we found he electronic dispersion relations to be around K points in a low energy approximation. Our results show that graphene bilayers exhibit zero band gap for all angles tested in this work. In boron nitride bilayers, the results reveal a tunable bandgap that satisfies the prediction of the bandgap found in one-dimensional diatomic systems presented in the literature.


2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Alex Summerfield ◽  
Andrew Davies ◽  
Tin S. Cheng ◽  
Vladimir V. Korolkov ◽  
YongJin Cho ◽  
...  

Abstract Graphene grown by high temperature molecular beam epitaxy on hexagonal boron nitride (hBN) forms continuous domains with dimensions of order 20 μm, and exhibits moiré patterns with large periodicities, up to ~30 nm, indicating that the layers are highly strained. Topological defects in the moiré patterns are observed and attributed to the relaxation of graphene islands which nucleate at different sites and subsequently coalesce. In addition, cracks are formed leading to strain relaxation, highly anisotropic strain fields, and abrupt boundaries between regions with different moiré periods. These cracks can also be formed by modification of the layers with a local probe resulting in the contraction and physical displacement of graphene layers. The Raman spectra of regions with a large moiré period reveal split and shifted G and 2D peaks confirming the presence of strain. Our work demonstrates a new approach to the growth of epitaxial graphene and a means of generating and modifying strain in graphene.


Author(s):  
F. J. Fraikor ◽  
A. W. Brewer

A number of investigators have examined moire patterns on precipitate particles in various age-hardening alloys. For example, Phillips has analyzed moire fringes at cobalt precipitates in copper and Von Heimendahl has reported on moire fringes in the system Al-Au. Recently, we have observed moire patterns on impurity precipitates in beryllium quenched in brine from 1000°C and aged at various temperatures in the range of 500-800°C. This heat treatment of beryllium rolled from vacuum cast ingots produces the precipitation of both an fee ternary phase, AlFeBe4, and an hcp binary phase, FeBe11. However, unlike a typical age-hardening alloy, the solute content of this material is low (less than 1000 ppm of Fe and 600 ppm of Al) and hence the total volume fraction of precipitates is small. Therefore there is some difficulty in distinguishing the precipitates and their orientation relationships with the beryllium matrix since the weak precipitate spots generally do not appear on the diffraction patterns.


Author(s):  
Hea In Jeong ◽  
Seo Young Choi ◽  
Young Ju Jeong

1991 ◽  
Vol 126 (1) ◽  
pp. 41-47
Author(s):  
P. A. Bezirganyan ◽  
S. E. Bezirganyan ◽  
A. O. Aboyan
Keyword(s):  
X Ray ◽  

2021 ◽  
Vol 104 (2) ◽  
Author(s):  
Wenzhao Li ◽  
C. J. O. Reichhardt ◽  
B. Jankó ◽  
C. Reichhardt

2014 ◽  
Vol 22 (20) ◽  
pp. 24840 ◽  
Author(s):  
Seok-Joo Byun ◽  
Seok Yong Byun ◽  
Jangkyo Lee ◽  
Won Mok Kim ◽  
Taek-Sung Lee

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