A contribution to the indexing of transmission electron diffraction patterns

A method for the indexing of TED spot patterns is presented. The reduced cell of the TED pattern defined by the two shortest vectors, which enclose an acute angle, serves as reference cell for the indexing. The d‐values of both the cell defining vectors and of their sum and difference vectors are determined being the four largest d‐values, which can be determined from the pattern. These four d‐values are compared with suitable d‐value sets of the possible crystalline phases and probable phase identifications are made. Generally, there exist several indexing variants for the individual d‐values of the separate phase identification possibilities. It is possible to find the correct indexing by the determination of the indices of the sum and difference vectors, occasionally, for one pair of the indexing variant from the vectors defining the reference cell and by comparison of these indices with the indexing variants for the d‐values of the sum and difference vectors of the corresponding phase identification variant. The measuring and calculation of the intervectorial angles formerly necessarily hasn't to be made in this method. However, the determination of the sum and difference vectors involves it. The reliability of the indexing can be increased in a strong manner if two or three different reciprocal lattice planes of the specimen under investigation are recorded in the corresponding TED patterns and if, in the following, these patterns can be indexed by the mentioned method without any doubt.