Materials Data on Sn4Bi2Se7 by Materials Project

Abstract

Sn4Bi2Se7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Sn2+ sites. In the first Sn2+ site, Sn2+ is bonded to six Se2- atoms to form SnSe6 octahedra that share a cornercorner with one BiSe6 octahedra, corners with four SnSe6 octahedra, edges with four equivalent BiSe6 octahedra, and edges with six SnSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–9°. There are a spread of Sn–Se bond distances ranging from 2.87–3.21 Å. In the second Sn2+ site, Sn2+ is bonded to six Se2- atoms to form SnSe6 octahedra that share corners with two equivalent BiSe6 octahedra, corners with three SnSe6 octahedra, edges with three equivalent BiSe6 octahedra, and edges with eight SnSe6 octahedra. The corner-sharing octahedra tilt angles range from 1–5°. There are a spread of Sn–Se bond distances ranging from 2.84–3.24 Å. Bi3+ is bonded to six Se2- atoms to form BiSe6 octahedra that share corners with three SnSe6 octahedra, corners with three equivalent BiSe6 octahedra, edges with two equivalent BiSe6 octahedra, and edges with seven SnSe6 octahedra. The corner-sharing octahedra tilt angles range from 0–6°. There are a spread of Bi–Se bond distances ranging from 2.93–3.01 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two Sn2+ and three equivalent Bi3+ atoms to form SeSn2Bi3 square pyramids that share corners with two equivalent SeSn5Bi octahedra, corners with five SeSn2Bi3 square pyramids, edges with three equivalent SeSn5Bi octahedra, and edges with four SeSn2Bi3 square pyramids. The corner-sharing octahedra tilt angles range from 1–3°. In the second Se2- site, Se2- is bonded to four Sn2+ and one Bi3+ atom to form SeSn4Bi square pyramids that share a cornercorner with one SeSn5Bi octahedra, corners with five SeSn2Bi3 square pyramids, edges with five equivalent SeSn5Bi octahedra, and edges with three SeSn2Bi3 square pyramids. The corner-sharing octahedral tilt angles are 2°. In the third Se2- site, Se2- is bonded to five Sn2+ and one Bi3+ atom to form SeSn5Bi octahedra that share corners with two equivalent SeSn5Bi octahedra, corners with three SeSn2Bi3 square pyramids, edges with three equivalent SeSn5Bi octahedra, and edges with eight SeSn2Bi3 square pyramids. The corner-sharing octahedral tilt angles are 5°. In the fourth Se2- site, Se2- is bonded in a square co-planar geometry to two equivalent Sn2+ and two equivalent Bi3+ atoms.