Crystallographic Merohedral Twinning / Single Project

Media Details

Media ID: SYM0012
Client: Technical
Created on: 2003-04-08
Published on: 2004-04-30
Dimensions: 1200 x 1600 pixels

Type: Illustration

Audiences: Technical, Scientific

Keywords: merohedral, twinning, hemihedral, crystallography, non-epitaxial, rotational, symmetry, point group, Laue, superimposable lattice

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  • Crystallographic Merohedral Twinning


Merohedral twinning is a special case of crystallographic twinning where the lattices of twin (different) domains (in a single crystal) overlap in three dimensions. An effect is superimposable lattices when the rotational symmetry of the lattice exceeds the rotational symmetry of the space group.

In this image, the crystal's unit cells are shown (3D squares, dark edges) with their contents as 7's. The crystal on the left is composed of two domains that represent a single untwinned crystal. The crystal on the right illustrates a merohedral twin, with the top domain rotated 180 degrees (rotation shown by red arrow).

An animation is available upon request.


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