L. Kienle

Real structure of KInS2 polytypes

Abstract KInS2 crystallizes in a two dimensionally ordered structure, which is related to the TlGaSe2-type structure. High-resolution transmission electron microscopy (HRTEM) and the analysis of diffuse scattering give evidence for defined shifts between ordered layers, which establish a lamellar nanostructure. The different arrangements of the lamellas, designated as A and B are fully compatible with the pseudosymmetry of KInS2. Consequently no misfit of the real structure can be observed by HRTEM. Only in rare cases the arrangement of the layers is at least partially ordered within extended domains and the diffuse scattering narrows into Bragg reflections. Two different strategies for the simulation of the diffuse scattering are presented. Besides the approximation of the diffuse scattering by Bragg intensities which are calculated on the basis of an ordered supercell, the diffuse scattering can also be simulated in dependence of the probability of AB or BA neighbors.