Model of superconductivity formation on ideal crystal lattice defect–twin or twin boundary (MSC-TB)

A new specimen preparation technique for visualizing macromolecules by conventional transmission electron microscopy has been developed. In this technique the biopolymer-molecule is embedded in a thin monocrystalline gold foil. Such embedding can be performed in the following way: the biopolymer is deposited on an epitaxially-grown thin single-crystal gold film. The molecule is then occluded by further epitaxial growth. In such an epitaxial sandwich an occluded molecule is expected to behave as a crystal-lattice defect and give rise to contrast in the electron microscope.The resolution of the method should be limited only by the precision with which the epitaxially grown gold reflects the details of the molecular structure and, in favorable cases, can approach the lattice resolution limit.In order to estimate the strength of the contrast due to the void-effect arising from occlusion of the DNA-molecule in a gold crystal some calculations were performed.

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Plasma Facing Material by Self-Interstitial Solid Solution Strengthening – Problem, Proposition, and a Solution

10.20944/preprints202010.0258.v1 ◽

2020 ◽

Author(s):

Muhammad Musaddique Ali Rafique

Keyword(s):

Solid Solution ◽

Crystal Lattice ◽

Point Defect ◽

Lattice Defect ◽

Solid Solution Strengthening ◽

Coordination Sites ◽

Pair Generation ◽

Solution Strengthening ◽

Fcc Structure ◽

Facing Material

Bubble (point defect) – a precursor of fuzz or under dense nanostructure formation is crystal lattice defect. Suitable selection of crystal lattice which inhibit Frenkel pair generation and intrinsically promotes selfinterstitial solid solution strengthening contributes effectively towards making plasma facing material. For this, interstitial sites, their size, amount / fraction, positions, tendency of occupation and diffusion parameters (e.g. activation energies (Q), activation volumes) are determined. Fcc iron carbon alloys (austenitic stainless steels AISI / SAE 321, fcc structure, Pearson code cF4, space group Fm3̅m) are proposed as suitable candidates. Along with their room temperature fcc structure having 12 interstitial positions (4 octahedral, 6 coordination sites and 8 tetrahedral, 4 coordination sites / unit cell) to allow insertion of self (iron) atoms, they have excellent corrosion resistance, thermal conductivity, and nonmagnetic properties. After their melting, casting, and machining to required dimensions and geometry, stabilizing heat treatment is applied to precipitate all carbon as TiC and prevent formation of Cr23C6 (sensitization). This resist heat and surface degradation and yield excellent architecture which not only inhibit Frankel pair generation but will also allow bulk assimilation or surface annihilation (loop punching) of this lattice point defect. A superior thermal, fluid, and structural design augment above

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Cathodoluminescence and Raman Spectromicroscopy of Forsterite in Tagish Lake Meteorite: Implications for Astromineralogy

International Journal of Spectroscopy ◽

10.1155/2016/1751730 ◽

2016 ◽

Vol 2016 ◽

pp. 1-8 ◽

Cited By ~ 1

Author(s):

Arnold Gucsik ◽

Ildikó Gyollai ◽

Hirotsugu Nishido ◽

Kiyotaka Ninagawa ◽

Matthew M. R. Izawa ◽

...

Keyword(s):

Lattice Defect ◽

Blue Emission ◽

Primary Crystallization ◽

Parent Body ◽

Chemical Inhomogeneity ◽

Low Grade ◽

Thermal Metamorphism ◽

Crystal Lattice Defect ◽

History Of ◽

Good Agreement

The Tagish Lake meteorite is CI/CM2 chondrite, which fell by a fireball event in January 2000. This study emphasizes the cathodoluminescence (CL) and Raman spectroscopical properties of the Tagish Lake meteorite in order to classify the meteoritic forsterite and its relation to the crystallization processes in a parent body. The CL-zoning of Tagish Lake meteorite records the thermal history of chondrules and terrestrial weathering. Only the unweathered olivine is forsterite, which is CL-active. The variation of luminescence in chondrules of Tagish Lake meteorite implies chemical inhomogeneity due to low-grade thermal metamorphism. The blue emission center in forsterite due to crystal lattice defect is proposed as being caused by rapid cooling during the primary crystallization and relatively low-temperature thermal metamorphism on the parent body of Tagish Lake meteorite. This is in a good agreement with the micro-Raman spectroscopical data. A combination of cathodoluminescence and micro-Raman spectroscopies shows some potentials in study of the asteroidal processes of parent bodies in solar system.

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Diffusion and Stress in Tungsten; Different Time Scales

Defect and Diffusion Forum ◽

10.4028/www.scientific.net/ddf.258-260.79 ◽

2006 ◽

Vol 258-260 ◽

pp. 79-84

Author(s):

Marek Danielewski ◽

Bartłomiej Wierzba

Keyword(s):

Stress Field ◽

Crystal Lattice ◽

Time Scales ◽

Transport Process ◽

Diffusion Time ◽

Ideal Crystal ◽

Effective Solution ◽

Nonuniform Temperature ◽

Transport Problems ◽

Different Time Scales

The Darken method is used to evaluate and compare different time scales in an ideal crystal lattice. The crystalline tungsten exemplifies presented approach. It is shown that in this metal and at 1273 K the time scales differ by nine orders of magnitude. Particular emphasis is given to the problem of deformation, the temperature and the mass diffusion time scales in tungsten quasicontinuum. The transport process in the nonuniform temperature and stress field is characterized by representative velocities. These velocities allow to quantify the time and length scales and can be used for the proper non-dimensialization and effective solution of the particular transport problems.

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Instability Of Ideal Crystal Lattice As A Reason Of Solids Plasticity

10.47204/emsr.1.2.2020.091-100 ◽

2020 ◽

Vol 1 (2) ◽

pp. 091-100

Author(s):

L. Kozak

Keyword(s):

Crystal Lattice ◽

Ideal Crystal

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Twin boundary structure of a Y-Ba-Cu-O superconductor

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100152811 ◽

1989 ◽

Vol 47 ◽

pp. 168-169

Author(s):

Yimei Zhu ◽

Masaki Suenaga ◽

R. L. Sabatini ◽

Youwen Xu

Keyword(s):

Twin Boundary ◽

Fine Particles ◽

Imaging Techniques ◽

Fine Powder ◽

Orthorhombic Phase ◽

Boundary Structure ◽

Crystallographic Axis ◽

System A ◽

High Resolution Structure ◽

Electron Microscopes

The (110) twin structure of YBa2Cu3O7 superconductor oxide, which is formed to reduce the strain energy of the tetragonal to orthorhombic phase transformation by alternating the a-b crystallographic axis across the boundary, was extensively investigated. Up to now the structure of the twin boundary still remained unclear. In order to gain insight into the nature of the twin boundary in Y-Ba-Cu-O system, a study using electron diffraction techniques including optical and computed diffractograms, as well as high resolution structure imaging techniques with corresponding computer simulation and processing was initiated.Bulk samples of Y-Ba-Cu-O oxide were prepared as described elsewhere. TEM specimens were produced by crushing bulk samples into a fine powder, dispersing the powder in acetone, and suspending the fine particles on a holey carbon grid. The electron microscopy during this study was performed on both a JEOL 2000EX and 2000FX electron microscopes operated at 200 kV.

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