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Dislocation Invisibility in Dark‐Field Electron Microscopy
Author(s) -
Dingley D. J.
Publication year - 1970
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19700380134
Subject(s) - invisibility , dark field microscopy , dislocation , condensed matter physics , electron microscope , field (mathematics) , reflection (computer programming) , materials science , microscopy , optics , crystallography , physics , chemistry , mathematics , computer science , pure mathematics , programming language
A study has been made of conditions governing dislocation invisibility in dark‐field electron microscopy when the usual invisibility criterion g · b = 0 is not satisfied. Experiments were conducted on f.c.c., b.c.c., and h.c. p. metals. Anomalous invisibilities of dislocations were observed in each case and also when using high order or low order reflection s. Computer produced dislocation profiles indicated that the occurrence of anomalous invisibility is strongly dependent on the foil thickness to extinction distance ratio. The effects of this on the validity of past measurements of Burgers vectors using electron microscopy techniques are discussed. It is concluded that although errors must have been incurred in the past, they would only constitute a minor fraction of the data obtained.