Microstructure of shock waves in crystal lattices

The spectra of the plasma emitted from the studied samples consist of several dozens of narrow bands superimposed on each other. Tables of spectral lines were used to interpret the spectra. It turned out that the largest number of bands corresponds to the radiation of positively charged ions and atoms of elements that make up the crystal lattices of minerals that make up the studied rocks. Thus, the spectra of the plasma emitted from quartz corresponded to the radiation of atoms and positively charged silicon ions, the charge of which varied from 1 to 4, as well as atoms and positively charged oxygen ions, the charge of which varied from 1 to 3. Positively charged ions and atoms of Si, O, K, Ca, Al and Na, which are part of the crystal lattices of quartz and feldspar, flew out of granites. Positively charged ions and Ca, C and O atoms flew out of the calcite.

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Propagation of shock waves in one-dimensional crystal lattices

Journal of Geophysical Research Atmospheres ◽

10.1029/jb085ib12p07025 ◽

1980 ◽

Vol 85 (B12) ◽

pp. 7025 ◽

Cited By ~ 14

Author(s):

T. G. Hill ◽

L. Knopoff

Keyword(s):

Shock Waves ◽

Crystal Lattices ◽

One Dimensional ◽

Dimensional Crystal

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The Interpretation of Crystal Lattice Images

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010009600x ◽

1972 ◽

Vol 30 ◽

pp. 550-551

Author(s):

J. M. Cowley ◽

Sumio Iijima

Keyword(s):

Crystal Orientation ◽

Diffraction Theory ◽

Phase Changes ◽

Electron Wave ◽

Crystal Lattices ◽

Heavy Atoms ◽

Lattice Images ◽

The Right ◽

Intuitive Interpretation ◽

Suitable Approximation

The imaging of detailed structures of crystal lattices with 3 to 4Å resolution, given the correct conditions of microscope defocus and crystal orientation and thickness, has been used by Iijima (this conference) for the study of new types of crystal structures and the defects in known structures associated with fluctuations of stoichiometry. The image intensities may be computed using n-beam dynamical diffraction theory involving several hundred beams (Fejes, this conference). However it is still important to have a suitable approximation to provide an immediate rough estimate of contrast and an evaluation of the intuitive interpretation in terms of an amplitude object.For crystals 100 to 150Å thick containing moderately heavy atoms the phase changes of the electron wave vary by about 10 radians suggesting that the “optimum defocus” theory of amplitude contrast for thin phase objects due to Scherzer and others can not apply, although it does predict the right defocus for optimum imaging.

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Investigation of shock-wave deformation history from recovered structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143754 ◽

1986 ◽

Vol 44 ◽

pp. 434-435

Author(s):

M.A. Mogilevsky ◽

L.S. Bushnev

Keyword(s):

Shock Wave ◽

Plastic Deformation ◽

Dislocation Density ◽

Shock Waves ◽

Shock Front ◽

Single Crystals ◽

Residual Deformation ◽

Deformation Structure ◽

Deformation History ◽

Deformation Velocity

Single crystals of Al were loaded by 15 to 40 GPa shock waves at 77 K with a pulse duration of 1.0 to 0.5 μs and a residual deformation of ∼1%. The analysis of deformation structure peculiarities allows the deformation history to be re-established.After a 20 to 40 GPa loading the dislocation density in the recovered samples was about 1010 cm-2. By measuring the thickness of the 40 GPa shock front in Al, a plastic deformation velocity of 1.07 x 108 s-1 is obtained, from where the moving dislocation density at the front is 7 x 1010 cm-2. A very small part of dislocations moves during the whole time of compression, i.e. a total dislocation density at the front must be in excess of this value by one or two orders. Consequently, due to extremely high stresses, at the front there exists a very unstable structure which is rearranged later with a noticeable decrease in dislocation density.

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Atomic resolution Z-contrast imaging of bulk crystal surfaces in Scanning Reflection Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010017520x ◽

1990 ◽

Vol 48 (4) ◽

pp. 414-415

Author(s):

Z. L. Wang ◽

J. Bentley

Keyword(s):

Electron Microscopy ◽

Elastic Scattering ◽

Dark Field ◽

Contrast Imaging ◽

Crystal Lattices ◽

Small Probe ◽

Scanning Transmission ◽

Annular Dark Field ◽

Image Position ◽

Z Contrast

The success of obtaining atomic-number-sensitive (Z-contrast) images in scanning transmission electron microscopy (STEM) has shown the feasibility of imaging composition changes at the atomic level. This type of image is formed by collecting the electrons scattered through large angles when a small probe scans across the specimen. The image contrast is determined by two scattering processes. One is the high angle elastic scattering from the nuclear sites,where ϕNe is the electron probe function centered at bp = (Xp, yp) after penetrating through the crystal; F denotes a Fourier transform operation; D is the detection function of the annular-dark-field (ADF) detector in reciprocal space u. The other process is thermal diffuse scattering (TDS), which is more important than the elastic contribution for specimens thicker than about 10 nm, and thus dominates the Z-contrast image. The TDS is an average “elastic” scattering of the electrons from crystal lattices of different thermal vibrational configurations,

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