Materials Data on Bi7I2 by Materials Project
Bi7I2 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are seven inequivalent Bi sites. In the first Bi site, Bi is bonded to six Bi atoms to form distorted edge-sharing BiBi6 octahedra. There are a spread of Bi–Bi bond distances ranging from 3.08–3.65 Å. In the second Bi site, Bi is bonded in a 3-coordinate geometry to three Bi atoms. Both Bi–Bi bond lengths are 3.07 Å. In the third Bi site, Bi is bonded to six Bi atoms to form a mixture of distorted edge and corner-sharing BiBi6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are one shorter (3.10 Å) and two longer (3.65 Å) Bi–Bi bond lengths. In the fourth Bi site, Bi is bonded to six Bi atoms to form a mixture of distorted edge and corner-sharing BiBi6 octahedra. The corner-sharing octahedral tilt angles are 13°. There are a spread of Bi–Bi bond distances ranging from 3.08–3.63 Å. In the fifth Bi site, Bi is bonded in a 2-coordinate geometry to two equivalent Bi and two I atoms. There are one shorter (3.10 Å) and one longer (3.20 Å) Bi–I bond lengths. In the sixth Bi site, Bi is bonded in a 6-coordinate geometry to three Bi and three equivalent I atoms. There are two shorter (3.64 Å) and one longer (3.69 Å) Bi–I bond lengths. In the seventh Bi site, Bi is bonded in a 6-coordinate geometry to four Bi atoms. Both Bi–Bi bond lengths are 3.06 Å. There are two inequivalent I sites. In the first I site, I is bonded in a single-bond geometry to four Bi atoms. In the second I site, I is bonded in a single-bond geometry to one Bi atom.