On the crystal structure of Bi11Se12Cl9

The structure of a compound previously described as Bi8Se9Cl6 has been dete rmined and refined to R = 0.040. It is very similar - if not identical - to the structure of a compound described as Bi11Se12Cl9. In contrast to the l atter, it accounts for a weak fourfold superstructure and therefore differs from it with respect to some important details. Our structure model is par tially disordered. It is closely related to the structure of BiSeCl and is mostly consistent with the chemical formula Bi11Se12Cl9.