Abstract
The R
3 space group inherently lacks 2110, m
001 and m_{{\bar 1}10} symmetry operations. However, in crystals with R
3 symmetry, these transformations produce `pseudoplanes' with the same interplanar spacing and angles as the original crystallographic planes, causing a lack of uniqueness in the electron diffraction (ED) pattern. The difference in atomic arrangements of pseudoplanes and original planes is reflected in the intensities of diffraction spots; it is hard to differentiate in standard ED patterns, frequently causing wrong assignment of the zone axes. The implications of this ambiguity in analysis of crystal orientations are discussed in detail and a suitable routine to follow while indexing R
3 ED patterns is proposed.
Publisher
International Union of Crystallography (IUCr)
Subject
Inorganic Chemistry,Physical and Theoretical Chemistry,Condensed Matter Physics,General Materials Science,Biochemistry,Structural Biology