scholarly journals Nonlinear propagating localized modes in a 2D hexagonal crystal lattice

2015 ◽  
Vol 301-302 ◽  
pp. 8-20 ◽  
Author(s):  
Janis Bajars ◽  
J. Chris Eilbeck ◽  
Benedict Leimkuhler
Keyword(s):  
Crystal Lattice ◽  
Hexagonal Crystal ◽  
Localized Modes

scholarly journals Two-dimensional mobile breather scattering in a hexagonal crystal lattice

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
Jānis Bajārs ◽  
J. Chris Eilbeck ◽  
Benedict Leimkuhler
Keyword(s):  
Crystal Lattice ◽  
Two Dimensional ◽  
Hexagonal Crystal

scholarly journals STRUCTURE AND MECHANICAL PROPERTIES OF POWDERS OBTAINED BY ELECTRODISPERGING COBALT-CHROMIUM ALLOY

2021 ◽  
pp. 1-7
Author(s):  
Alexey Ivanovich Pykhtin
Keyword(s):  
Crystal Lattice ◽  
Mechanical Action ◽  
Particle Sizes ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
Hexagonal Crystal ◽  
Orthorhombic Crystal ◽  
Cubic Crystal ◽  
Working Fluids ◽  
Elliptical Particles

The work presents the results of attestation of powders that were obtained from the KHMS "Cellite" alloy (Co - 63%, Cr - 27%, Mo - 5%, Ni - 2%, Fe - 2%) by electroerosive dispersion under various technological conditions (voltage from 100 V to 220 V, the capacitance of condenser from 15 μF to 50 μF, pulse frequency from 100 Hz to 200 Hz), and with using working fluids of different chemical composition and properties (water, kerosene, butyl alcohol). The study of the dispersion of the obtained powders, based on the results, established: the range of particle sizes is from 20 μm to 110 μm depending on the production modes. The results show various particle sizes, both a few nanometers and hundreds of microns. Depending on the technological modes of production, various mechanisms of the formation of powder particles can occur. Flake particles ranging in size from a few nanometers to (as a rule) one micron are obtained by the crystallization of the material vapor. They usually form agglomerates or stick to larger particles. Spherical and elliptical particles with a diameter from tens of nanometers to hundreds of microns were formed in crystallized material upon melting. The result of thermal and mechanical action during electroerosive dispersion was fragmentation grains with an average size from units to hundreds of microns. To meet the requirements for powders used in additive machines, it is necessary to select modes that exclude brittle destruction of the particles of the powder material and ensure the production of spherical or elliptical particles in the required particle size ranges. As a result of the experiment during the study of the phase composition of powders, using various technological modes and the composition of working fluids, the following phases were revealed: Cobalt (Co) with a cubic crystal lattice, a = b = c = 3.561079 Å; Chromium (Cr) with a hexagonal crystal lattice a = b = 2.738459 Å, c = 4.55078 Å; Nickel (Ni) with a hexagonal crystal lattice, a = b = 2.652590 Å, c = 4.380519 Å; sigma-Cr7Co3 (Cr7Co3 with a tetragonal crystal lattice, a = b = 8.656172 Å, c = 4.484030 Å; Cobalt Iron (CoFe), with a cubic crystal lattice, a = b = c = 2.846754 Å; Chromium Carbide (Cr3C2) with an orthorhombic crystal lattice: a = 2.821Å, b = 5.53Å and c = 11.47Å; Iron (Fe) with a cubic crystal lattice, a = b = c = 3.604293 Å; Cobalt Carbide (Co3C), with an orthorhombic crystal lattice, a = b = 4.455931 Å, c = 6.86598 Å; Cobalt Oxide (CoO) with a cubic crystal lattice a = b = c = 4.563279 Å; Magnetite (Fe3O4) with a cubic crystal lattice a = b = c = 8.4774342 Å.  

Evolution and stability of self-localized modes in a nonlinear inhomogeneous crystal lattice

1995 ◽  
Vol 52 (17) ◽  
pp. 12736-12742 ◽  
Author(s):  
A. D. Boardman ◽  
V. Bortolani ◽  
R. F. Wallis ◽  
K. Xie ◽  
H. M. Mehta
Keyword(s):  
Crystal Lattice ◽  
Localized Modes ◽  
Inhomogeneous Crystal

scholarly journals Two-dimensional nonlinear wave scattering in a hexagonal crystal lattice

2021 ◽  
Author(s):  
Jānis Bajārs ◽  
◽  
J.Chris Eilbeck ◽  
Benedict Leimkuhler ◽  
◽  
...  
Keyword(s):  
Crystal Lattice ◽  
Nonlinear Wave ◽  
Wave Scattering ◽  
Two Dimensional ◽  
Hexagonal Crystal

Origin of the alternate bright/dark contrast in HREM images of hexagonal crystals, particularly 6H-SiC

1993 ◽  
Vol 51 ◽  
pp. 914-915
Author(s):  
J.S. Bow ◽  
R.W. Carpenter ◽  
M.J. Kim
Keyword(s):  
High Resolution ◽  
Incident Beam ◽  
Hexagonal Crystal ◽  
Detailed Explanation ◽  
Similar Character ◽  
High Resolution Images ◽  
The Difference ◽  
Zigzag Shape ◽  
Hexagonal Crystals ◽  
Dark Contrast

A prominent characteristic of high-resolution images of 6H-SiC viewed from [110] is a zigzag shape with a period of 6 layers as shown in Fig.1. Sometimes the contrast is same through the 6 layers of (0006) planes (Fig.1a), but in most cases it appears as in Fig.1b -- alternate bright/dark contrast among every three (0006) planes. Alternate bright/dark contrast is most common for the thicker specimens. The SAD patterns of these two types of image are almost same, and there is no indication that the difference results from compositional ordering. O’Keefe et al. concluded this type of alternate contrast was due to crystal tilt in thick parts of the specimen. However, no detailed explanation was given. Images of similar character from Ti3Al, which is also a hexagonal crystal, were reported by Howe et al. Howe attributed the bright/dark contrast among alternate (0002) Ti3Al planes to phase shifts produced by incident beam tilt.

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