Structure of phases of the sillenite family in the Bi2O3-V2O5 system

X-ray diffraction studies of sillenite Bi24V2O40 single crystals grown by the hydrothermal method are performed for a separate crystal and powdered crystals. It is found that the composition of the two specimens is described by the (Bi24 − x ▭ x )[Bi y 3+ V 1−y 5+ ]2 O40 general formula with completely populated oxygen sites but differs in the content of vacancies at the bismuth site (this was established for the first time) and the Bi: V ratio at the tetrahedral site. The structural models of all the vanadium-containing sillenites reported in the literature are considered, and the possibility that Bi atoms are located at the centers of BiO4 tetrahedra is established.