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The effect of three‐fold astigmatism on measurements of grain boundary volume expansion by high‐resolution transmission electron microscopy
Author(s) -
Merkle K. L.,
Csencsits R.,
Rynes K. L.,
Withrow J. P.,
Stadelmann P. A.
Publication year - 1998
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1046/j.1365-2818.1998.2890841.x
Subject(s) - grain boundary , optics , lattice (music) , transmission electron microscopy , condensed matter physics , materials science , electron microscope , physics , geometry , crystallography , chemistry , mathematics , microstructure , acoustics
In the absence of high‐order aberrations, the lattice fringe technique should allow measurement of grain boundary rigid‐body displacements to accuracies about an order of magnitude better than the point‐to‐point resolution of the transmission electron microscope. The three‐fold astigmatism, however, introduces shifts of the lattice fringe pattern that depend on the orientation of the lattice relative to the direction of the three‐fold astigmatism and thus produces an apparent shift between the two grains bordering the grain boundary. By image simulation of grain boundary model structures, the present paper explores the effect of these extraneous shifts on grain boundary volume expansion measurements. It is found that the shifts depend, among others, on zone axis direction and the magnitude of the lattice parameter. For many grain boundaries of interest, three‐fold astigmatism correction to better than 100 nm appears necessary to achieve the desired accuracies.