DOE OSTI2020
K3BiAs6Se12 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six Se2- atoms to form KSe6 octahedra that share faces with two equivalent BiSe6 octahedra. All K–Se bond lengths are 3.37 Å. In the second K1+ site, K1+ is bonded in a distorted q6 geometry to nine Se2- atoms. There are a spread of K–Se bond distances ranging from 3.54–3.78 Å. Bi3+ is bonded to six Se2- atoms to form BiSe6 octahedra that share faces with two equivalent KSe6 octahedra. There are two shorter (3.00 Å) and four longer (3.01 Å) Bi–Se bond lengths. There are three inequivalent As3+ sites. In the first As3+ site, As3+ is bonded in a distorted trigonal non-coplanar geometry to three Se2- atoms. There are a spread of As–Se bond distances ranging from 2.38–2.49 Å. In the second As3+ site, As3+ is bonded in a distorted trigonal non-coplanar geometry to three Se2- atoms. There are a spread of As–Se bond distances ranging from 2.38–2.49 Å. In the third As3+ site, As3+ is bonded in a distorted trigonal non-coplanar geometry to three Se2- atoms. There are a spread of As–Se bond distances ranging from 2.38–2.49 Å. There are six inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 4-coordinate geometry to two K1+, one Bi3+, and one As3+ atom. In the second Se2- site, Se2- is bonded in a 4-coordinate geometry to two K1+, one Bi3+, and one As3+ atom. In the third Se2- site, Se2- is bonded in a 4-coordinate geometry to two K1+, one Bi3+, and one As3+ atom. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to two equivalent K1+ and two As3+ atoms. In the fifth Se2- site, Se2- is bonded in a 4-coordinate geometry to two equivalent K1+ and two As3+ atoms. In the sixth Se2- site, Se2- is bonded in a 2-coordinate geometry to two equivalent K1+ and two As3+ atoms.