SUPERSPACE-GROUP APPROACH TO THE MODULATED STRUCTURE OF THE INORGANIC MISFIT LAYER COMPOUND (LAS)1.14NBS2

The structure of the inorganic misfit layer compound (LaS)1.14NbS2 is reanalysed in the superspace-group formalism, using the recent single-crystal x-ray diffraction data obtained by Meerschaut, Rabu and Rouxel. Structure refinements make it possible to determine the values of the modulation functions of the various atoms. The largest modulation amplitudes are found on the La atoms and on the sulphur atoms of the NbS2 subsystem. They mainly describe displacements in the plane of the layers. A detailed analysis is given of the coordination of various atoms by plotting interatomic distances as a function of the incommensurate phase parameter.