Materials Data on K4Cu8Te11 by Materials Project
K4Cu8Te11 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 5-coordinate geometry to eight Te+1.45- atoms. There are a spread of K–Te bond distances ranging from 3.66–4.06 Å. In the second K1+ site, K1+ is bonded in a 1-coordinate geometry to ten Te+1.45- atoms. There are a spread of K–Te bond distances ranging from 3.39–4.02 Å. In the third K1+ site, K1+ is bonded in a 8-coordinate geometry to eight Te+1.45- atoms. There are a spread of K–Te bond distances ranging from 3.61–3.95 Å. In the fourth K1+ site, K1+ is bonded to twelve Te+1.45- atoms to form KTe12 cuboctahedra that share corners with fourteen CuTe4 tetrahedra, edges with three equivalent KTe12 cuboctahedra, and faces with eight CuTe4 tetrahedra. There are a spread of K–Te bond distances ranging from 3.70–3.96 Å. There are four inequivalent Cu+1.50+ sites. In the first Cu+1.50+ site, Cu+1.50+ is bonded to four Te+1.45- atoms to form CuTe4 tetrahedra that share corners with two equivalent KTe12 cuboctahedra, corners with six CuTe4 tetrahedra, edges with two CuTe4 tetrahedra, and a faceface with one KTe12 cuboctahedra. There are a spread of Cu–Te bond distances ranging from 2.60–2.67 Å. In the second Cu+1.50+ site, Cu+1.50+ is bonded to four Te+1.45- atoms to form CuTe4 tetrahedra that share corners with two equivalent KTe12 cuboctahedra, corners with six CuTe4 tetrahedra, edges with two CuTe4 tetrahedra, and a faceface with one KTe12 cuboctahedra. There are a spread of Cu–Te bond distances ranging from 2.61–2.68 Å. In the third Cu+1.50+ site, Cu+1.50+ is bonded to four Te+1.45- atoms to form CuTe4 tetrahedra that share corners with two equivalent KTe12 cuboctahedra, corners with six CuTe4 tetrahedra, edges with two equivalent CuTe4 tetrahedra, and a faceface with one KTe12 cuboctahedra. There are a spread of Cu–Te bond distances ranging from 2.57–2.70 Å. In the fourth Cu+1.50+ site, Cu+1.50+ is bonded to four Te+1.45- atoms to form CuTe4 tetrahedra that share a cornercorner with one KTe12 cuboctahedra, corners with four CuTe4 tetrahedra, an edgeedge with one CuTe4 tetrahedra, and a faceface with one KTe12 cuboctahedra. There are a spread of Cu–Te bond distances ranging from 2.59–2.71 Å. There are nine inequivalent Te+1.45- sites. In the first Te+1.45- site, Te+1.45- is bonded in a 8-coordinate geometry to three K1+, four Cu+1.50+, and one Te+1.45- atom. The Te–Te bond length is 2.93 Å. In the second Te+1.45- site, Te+1.45- is bonded in a 8-coordinate geometry to three K1+, four Cu+1.50+, and one Te+1.45- atom. The Te–Te bond length is 2.93 Å. In the third Te+1.45- site, Te+1.45- is bonded in a 3-coordinate geometry to five K1+ and two equivalent Cu+1.50+ atoms. In the fourth Te+1.45- site, Te+1.45- is bonded in a 7-coordinate geometry to two equivalent K1+, four Cu+1.50+, and one Te+1.45- atom. In the fifth Te+1.45- site, Te+1.45- is bonded in a 2-coordinate geometry to three K1+, two Cu+1.50+, and one Te+1.45- atom. The Te–Te bond length is 2.86 Å. In the sixth Te+1.45- site, Te+1.45- is bonded to three equivalent K1+ and four Cu+1.50+ atoms to form a mixture of distorted edge and corner-sharing TeK3Cu4 pentagonal bipyramids. In the seventh Te+1.45- site, Te+1.45- is bonded in a 7-coordinate geometry to four K1+, two equivalent Cu+1.50+, and one Te+1.45- atom. The Te–Te bond length is 2.91 Å. In the eighth Te+1.45- site, Te+1.45- is bonded in a 2-coordinate geometry to four K1+, two Cu+1.50+, and one Te+1.45- atom. The Te–Te bond length is 2.88 Å. In the ninth Te+1.45- site, Te+1.45- is bonded in a 9-coordinate geometry to four K1+ and four equivalent Cu+1.50+ atoms.