W0463

Multiple Twinning of Diamond. Sam Ick Son, Su Jin Chung, School of Materials Science and Engineering, Seoul National Univ., Seoul 151-744, Korea.

The relation between domains and domain boundaries of multiple twins of diamond were investigated by electron back scatter diffraction (EBSD) method and high resolution transmission electron microscopy (HRTEM).

Multiple twinned diamonds has two types of morphologies. One is almost perfect icosahedron in which all faces are {111} faces. The other is a hollow icosahedron similar to the Kepler-Poinsot polyhedron. The indented negative trigonal faces are formed with {100} faces of cube. The convex edges of the twinned icosahedron could be confirmed to Σ3 whereas the concave edges could be assigned to Σ9 twin boundary by the EBSD pattern matching.