New method to determine the parity of the number of twin planes in tabularsilver halide microcrystals from top views

A new method is presented to determine from top views whether a tabular sil ver halide crystal contains an even or an odd number of twin planes. The mo del is based on the occurrence of diffuse intensity contours in diffraction patterns of the crystals. This implies that this information can be correl ated with simultaneous observations of the shape of the tabular crystals (h exagonal or triangular). Moreover, it will be shown that this method allows one to determine from top views in which variant of an even twinned crysta l dislocations are present.