scholarly journals Nanostructural crystallization of metals

2021 ◽  
pp. 23-26
Author(s):  
E. I. Marukovich ◽  
V. Yu. Stetsenko ◽  
A. V. Stetsenko
Keyword(s):  
Thermodynamic Calculations ◽  
Tetragonal Structure ◽  
Degree Of Branching ◽  
Trigonal Structure ◽  
Hexagonal Crystals

Based on thermodynamic calculations, it is shown that metal crystallization is an equilibrium nanostructural process. At the beginning, trigonal or tetragonal structure-forming nanocrystals are formed from elementary nanocrystals. Then crystallization centers are formed from them. Further, tetragonal or hexagonal dendrites are formed from them and tetragonal or trigonal structure-forming nanocrystals. Their forms depend on the degree of branching of dendrites. The most branched of them (compact dendrites) are tetragonal or hexagonal crystals.

Mechanical properties, electronic properties and phase stability of Mg under pressure: A first-principles study

2014 ◽  
Vol 28 (29) ◽  
pp. 1450200 ◽  
Author(s):  
Jian Li ◽  
Xu Dong ◽  
Ye Jin ◽  
Changzeng Fan
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
Tetragonal Structure ◽  
Face Centered Cubic ◽  
Trigonal Structure ◽  
Hcp Structure ◽  
Structure Density ◽  
Face Centered ◽  
The Stability ◽  
Directional Bonding

Magnesium (Mg) crystal structures are extensively explored using an evolutionary algorithm implemented in the USPEX code. Two structures with simple trigonal and tetragonal symmetries are discovered to possibly exist under high pressure. The stability of these symmetries is determined by elastic constants and phonon spectrum calculations. First-principle calculations are performed to investigate the structural, mechanical and electronic properties of different Mg structures under high pressure (up to 300 GPa). Above 190 GPa, the trigonal structure is more stable than the hexagonal close-packed (HCP) structure. Particularly, the trigonal structure can be considered a compromise between face-centered cubic (FCC) and HCP blocks. Interestingly, the tetragonal structure density is only 95% HCP structure. In addition, the tetragonal structure has strong directional bonding but is less stable than the HCP structure (up to 600 GPa). Pressure significantly changes the electronic properties of both structures although they remain metallic up to 300 GPa.

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.

Thermodynamic calculations of linear chain molecules using a SAFT model

2001 ◽  
Vol 99 (1) ◽  
pp. 65-76 ◽  
Author(s):  
Yiping Tang, Zhaohui Wang, Benjamin C.-Y.
Keyword(s):  
Linear Chain ◽  
Thermodynamic Calculations ◽  
Chain Molecules

Coupled Mass and Heat Transport Models for Nuclear Fuels using Thermodynamic Calculations

2018 ◽  
Author(s):  
Srdjan Simunovic ◽  
Jake W. Mcmurray ◽  
Theodore M. Besmann ◽  
Emily Moore ◽  
Markus H. A. Piro
Keyword(s):  
Heat Transport ◽  
Thermodynamic Calculations ◽  
Nuclear Fuels ◽  
Transport Models

The degree of branching of 4-O-methylglucuronoxylan from white willow (Salix alba L.)

1968 ◽  
Vol 33 (8) ◽  
pp. 2518-2525 ◽  
Author(s):  
M. Kubačková ◽  
Š. Karácsonyi ◽  
J. Hrivňák
Keyword(s):  
Salix Alba ◽  
Degree Of Branching ◽  
White Willow

scholarly journals Investigations of polyethylene of raised temperature resistance service performance using autoclave test under sour medium conditions

e-Polymers ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 346-354
Author(s):  
Guoquan Qi ◽  
Hongxia Yan ◽  
Dongtao Qi ◽  
Houbu Li ◽  
Lushi Kong ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Service Performance ◽  
Degree Of Branching ◽  
Temperature Resistance ◽  
Temperature Conditions ◽  
Dimensional Network ◽  
Gas Medium ◽  
Better Than

Abstract The chapter deals with the performance evaluation of the polyethylene of raised temperature resistance (PE-RT) and polyethylene (PE) using autoclave test under sour oil and gas medium conditions. The analyses of performance changes showed that PE-RT has good media resistance at 60°C. As the temperature increases, its mechanical properties decrease, accompanied by an increase in weight. Comparative analyses showed that no matter what temperature conditions are, PE-RT media resistance is better than PE80. The better media resistance of PE-RT depends on its higher degree of branching. Short branches are distributed between the crystals to form a connection between the crystals, thereby improving its heat resistance and stress under high-temperature conditions. PE-RT forms an excellent three-dimensional network structure through copolymerization, ensuring that it has better media resistance than PE80. However, the mechanical performance will be attenuated due to the high service temperature.

Observations on crystals found in the intestine of Nematodirus battus during the development of immunity to this nematode in lambs

Parasitology ◽  
1976 ◽  
Vol 72 (1) ◽  
pp. 75-80 ◽  
Author(s):  
J. Martin ◽  
D. L. Lee
Keyword(s):  
X Ray ◽  
Infective Larvae ◽  
Adult Nematode ◽  
Hexagonal Crystals

Lambs which were given 60000 infective larvae ofNematodirus battus progressively threw off adult nematodes from day 20 onwards. Large, hexagonal crystals appeared in the intestine of the adult nematode at about this time and caused blockage of the intestinal-rectal or -cloacal junction. Lambs which were given 1000–2000 infective larvae did not throw off the infection, and adult nematodes from lambs which had been infected for up to 74 days did not contain these crystals. Chemical, histo-chemical and X-ray microanalysis tests on the crystals indicated that they are lipoprotein in composition. The crystals arise within the lumen of the nematode and appear to be associated with the development of immunity to this nematode in lambs.

Materials, Devices and Spin Transfer Torque in Antiferromagnetic Spintronics: A Concise Review

SPIN ◽  
2017 ◽  
Vol 07 (03) ◽  
pp. 1740014 ◽  
Author(s):  
Cormac Ó Coileáin ◽  
Han Chun Wu
Keyword(s):  
Magnetic Fields ◽  
Spin Transfer Torque ◽  
Spin Transfer ◽  
Tetragonal Structure ◽  
Next Generation ◽  
Tunnel Magnetoresistance ◽  
Spintronic Devices ◽  
Concise Review ◽  
Plane Anisotropy ◽  
Magnetic States

From historical obscurity, antiferromagnets are recently enjoying revived interest, as antiferromagnetic (AFM) materials may allow the continued reduction in size of spintronic devices. They have the benefit of being insensitive to parasitic external magnetic fields, while displaying high read/write speeds, and thus poised to become an integral part of the next generation of logical devices and memory. They are currently employed to preserve the magnetoresistive qualities of some ferromagnetic based giant or tunnel magnetoresistance systems. However, the question remains how the magnetic states of an antiferromagnet can be efficiently manipulated and detected. Here, we reflect on AFM materials for their use in spintronics, in particular, newly recognized antiferromagnet Mn2Au with its in-plane anisotropy and tetragonal structure and high Néel temperature. These attributes make it one of the most promising candidates for AFM spintronics thus far with the possibility of architectures freed from the need for ferromagnetic (FM) elements. Here, we discuss its potential for use in ferromagnet-free spintronic devices.

scholarly journals Hexane isomers separation on an isoreticular series of microporous Zr carboxylate metal organic frameworks

2020 ◽  
Vol 8 (34) ◽  
pp. 17780-17789
Author(s):  
Adriano Henrique ◽  
Tanmoy Maity ◽  
Hengli Zhao ◽  
Pedro F. Brântuas ◽  
Alírio E. Rodrigues ◽  
...  
Keyword(s):  
High Selectivity ◽  
Metal Organic Frameworks ◽  
Degree Of Branching ◽  
Molecular Separation ◽  
Metal Organic ◽  
Gcmc Simulations

The microporous MOF MIL-140B can separate hexane isomers according to the degree of branching, linear >mono-branched >di-branched, with a remarkably high selectivity up to 10 at 343 K. GCMC simulations confirm the origins of the molecular separation.

Sign in / Sign up

Export Citation Format

Share Document