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The critical voltage effect in transmission electron microscopy . V. The case of non‐centrosymmetric crystals
Author(s) -
Serneels R.,
David M.,
Gevers R.
Publication year - 1975
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.2220720113
Subject(s) - octahedron , condensed matter physics , tetrahedron , materials science , transmission electron microscopy , voltage , crystallography , chemistry , physics , crystal structure , nanotechnology , quantum mechanics
The critical voltage effect is discussed for the case of noncentrosymmetric crystals (systematic reflections only). An appropriate measure of the noncentrosymmetry is found in terms of the phase angles θ g and θ 2 g of the lowest order extinction distances i.e. Δ = θ 2 g –2θ g . When |Δ| ≦ 3° a critical voltage effect is still expected. For larger |Δ|‐values usually no critical voltage effect will occur. As an application the case is considered of interstitial alloys such as V 2 H, Nb 2 H, and Nb 2 O. For these alloys the critical voltage effect may be used to determine whether the H or O are in octahedral or tetrahedral interstitial positions.