HIGH‐RESOLUTION ELECTRON MICROSCOPE IMAGES OF CRYSTAL LATTICE PLANES USING CONICAL ILLUMINATION

1970 ◽  
Vol 16 (12) ◽  
pp. 515-516 ◽  
Author(s):  
Klaus Heinemann ◽  
Helmut Poppa
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Crystal Lattice ◽  
Resolution Electron ◽  
Microscope Images ◽  
High Resolution Electron Microscope ◽  
Lattice Planes

High Resolution Lattice Images of G.P.Zones and Solute Clusters in Al-Cu and Cu-Be Alloys

1982 ◽  
Vol 21 ◽  
Author(s):  
H. Yoshida ◽  
H. Hashimoto ◽  
Y. Yokota ◽  
M. Takeda
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Atomic Structures ◽  
Resolution Electron ◽  
Microscope Images ◽  
Lattice Images ◽  
Lattice Planes

ABSTRACTAtomic structures of G.P. zones and solute clusters in Al-Cu and Cu-Be alloys are studied by the atom resolution electron microscope images. The images of plate-like G.P. zones appear as dotted images with various brightnesses along (200) lattice planes. The solute clusters are also observed along (111) lattice planes.

APERIODIC SELF-REPLICATING INORGANIC STRUCTURES

2000 ◽  
Vol 14 (10) ◽  
pp. 337-344 ◽  
Author(s):  
LESLIE A. BURSILL
Keyword(s):  
Electron Microscope ◽  
High Resolution ◽  
Clay Mineral ◽  
Growth Mechanism ◽  
Kinetic Equations ◽  
Shell Structures ◽  
Prototype Model ◽  
Resolution Electron ◽  
Microscope Images ◽  
High Resolution Electron Microscope

A prototype model is introduced for self-replicating octahedral shell structures. The structure is inherently aperiodic and unable to grow like a normal crystal. Conditions under which this growth mechanism may become favored energetically are discussed. High-resolution electron microscope images of the clay mineral allophane, an analog of the spheroidal fullerenes, are described. Kinetic equations are derived assuming an autocatalytic self-replicating growth mechanism for this model. More general mathematical treatments of self-replicating systems are also reviewed and discussed.

Extension of the “thin-crystal” condition by small crystal tilts: Why HREM images of SiC polytypes always look tilted

1992 ◽  
Vol 50 (1) ◽  
pp. 116-117
Author(s):  
Michael A. O'Keefe ◽  
Velimir Radmilovic
Keyword(s):  
Silicon Carbide ◽  
Electron Microscope ◽  
High Resolution ◽  
Group Symmetry ◽  
Crystal Thickness ◽  
Resolution Electron ◽  
Microscope Images ◽  
High Resolution Electron Microscope ◽  
Simulated Images ◽  
Thin Crystal

Both experimental and simulated high-resolution electron microscope images of silicon carbide polytypes commonly exhibit symmetry changes in thicker crystal regions compared to the perfect (projected) space group symmetry of images from thin crystals. However, the changes predicted by simulation, and those found experimentally, are quite different.High-resolution transmission electron microscope images of silicon carbide polytypes were obtained with the JEOL ARM-1000 high-resolution electron microscope in the course of an investigation into a series of metal matrix composites. Like all HRTEM images of silicon carbide, these images failed to show the correct symmetry in the thicker parts of the specimen. Changes in image symmetry as crystal thickness is increased also occur when images of silicon carbide are simulated; for example, Smith and O'Keefe simulated images of polytypes of silicon carbide for crystals oriented so that the electron beam was precisely along the <1210> direction, and found marked departure from thin-crystal symmetry at thicknesses of the order of 150Å for an electron energy of 500keV. However, the lack of symmetry in their simulated images appears to be due to the presence of many second-order terms contributing to the intensity spectra of the thick-crystal images, whereas the symmetry changes in experimental images from thicker crystals are usually of the form that preserves the thin-crystal-like contrast for one set of “twin” spots, yet smears out the contrast of the other. A typical example of this latter effect can be seen in the image of the 6H variant of SiC shown in figure 1.

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