Preparation and structural properties of new series of mixed-anion compounds: rare earth fluorosulfides

Rare earth fluorosulfides with the following compositions: LnSF and Ln2AF4S2 have been prepared by solid state routes. These structures can be described as a stacking of fluoride-based slabs ([Ln2F2]4+ in LnSF and [Ln2AF4]4+ in Ln2AF4S2) and double layers [S2]4−. The fluoride blocks are related to fluorite-type structure. The relative compactness of the fluoride blocks leads to a relaxation of the LnS bond lengths.