Grain boundary analysis in TEM. V. A. Criterion for the identification of a CSL and a characterization of an approximate CSL

The identification of a bicrystal with possible approximate CSL's is performed using the matrix product of their rotation matrices. The approximation is expressed by a small angle rotation matrix of the form of a sum of a unitary matrix and a skew symmetric matrix. This supplementary rotation may only be determined after appropriate treatment of the symmetrically equivalent descriptions. It is also, based on the comparison of an experimental case with tables of CSL's given in their description using the greatest rotation angle, generally 180°. That deviation expressed by a small angle rotation may easily be presented in terms of a small angle twist component and a small angle tilt component.