Chapter 1.3 Twinning
Mathematical, physical and chemical tables
First Online Edition (2006)
Part 1. Crystal geometry and symmetry
Published Online: 1 JAN 2006
© International Union of Crystallography 2006
International Tables for Crystallography
How to Cite
Koch, E. 2006. Twinning. International Tables for Crystallography. C:1:1.3:10–14.
- Published Online: 1 JAN 2006
In Section 1.3.1, general terms with reference to twinning are explained. Subsequently, the terms ‘twin lattice’ and ‘twin index’ are defined and illustrated by several examples in Section 1.3.2 and the implication of twinning on the reflection pattern in reciprocal space is discussed in Section 1.3.3. Twinning by merohedry and by pseudo‐merohedry is described in Section 1.3.4. For each combination of point group and Bravais lattice, the possible twin operations for twins by merohedry are given in Table 18.104.22.168. Table 22.214.171.124 shows the simulated Laue classes, the extinction symbols, the simulated ‘possible space groups’ and the possible true space groups for crystals twinned by merohedry. For cases in which the twin element cannot be recognized by direct inspection, a procedure for the calculation of the twin element is described in Section 1.3.5.
- calculation of the twin element;