Abstract
It is often the case with the structure of a complex sulfide that a pseudo-cell is revealed, due to a nearly regular arrangement of either metal or sulfur or both on sublattice nodes. The Fourier tranform of such a struc-ture was studied and the conclusion was deduced that a repetition of intensity distribution, with a period reciprocal to the pseudo-cell, will be observed in its X-ray diffraction pattern.
Conversely, if we observe a repetition in intensity distribution of an X-ray diffraction pattern, we can not only conclude that the structure comprises a preudo-subcell, but also arrive at the derivation of the structure by assigning appropriate phases only to those reflections that are found within an asymmetric unit of the repetition.
This principle has been successfully applied to the determination of the structure of zinkenite, PbS.Sb2S3.
