Discovery and Structure Determination of an Unusual Sulfide Telluride through an Effective Combination of TEM and Synchrotron Microdiffraction

The structure elucidation of the novel sulfide telluride Pb₈Sb₈S₁₅Te₅ demonstrates a new versatile procedure that exploits the synergism of electron microscopy and synchrotron diffraction methods for accurate structure analyses of side‐phases in heterogeneous microcrystalline samples. Suitable crystallites of unknown compounds can be identified by transmission electron microscopy and relocated and centered in a microfocused synchrotron beam by means of X‐ray fluorescence scans. The refined structure model is then confirmed by simulating HRTEM images of the same crystallite. Pb₈Sb₈S₁₅Te₅ consists of chains of heterocubane‐like units. Cation coordination polyhedra form unusually entwined chains of edge‐ and face‐sharing bicapped trigonal prisms. The structure data are precise enough for bond‐valence calculations, which confirm the disordered atom distribution. On this basis, optimization of physical properties becomes feasible.