DOE OSTI2020
Cu17Se10 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are seventeen inequivalent Cu+1.18+ sites. In the first Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with fifteen CuSe4 tetrahedra and edges with three equivalent CuCu3Se4 tetrahedra. There are one shorter (2.35 Å) and three longer (2.47 Å) Cu–Se bond lengths. In the second Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.39–2.58 Å. In the third Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of distorted edge and corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.42–2.80 Å. In the fourth Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.46–2.55 Å. In the fifth Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.41–2.49 Å. In the sixth Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of distorted edge and corner-sharing CuSe4 trigonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.38–2.95 Å. In the seventh Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.46–2.62 Å. In the eighth Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.50–2.53 Å. In the ninth Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of edge and corner-sharing CuSe4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.36–2.56 Å. In the tenth Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form corner-sharing CuSe4 trigonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.37–2.58 Å. In the eleventh Cu+1.18+ site, Cu+1.18+ is bonded to four Se2- atoms to form a mixture of distorted edge and corner-sharing CuSe4 tetrahedra. There are three shorter (2.41 Å) and one longer (2.87 Å) Cu–Se bond lengths. In the twelfth Cu+1.18+ site, Cu+1.18+ is bonded in a 3-coordinate geometry to three equivalent Cu+1.18+ and four Se2- atoms. There are two shorter (2.47 Å) and one longer (2.48 Å) Cu–Cu bond lengths. There are a spread of Cu–Se bond distances ranging from 2.46–2.95 Å. In the thirteenth Cu+1.18+ site, Cu+1.18+ is bonded in a 12-coordinate geometry to six Cu+1.18+ and six Se2- atoms. All Cu–Cu bond lengths are 2.60 Å. There are a spread of Cu–Se bond distances ranging from 2.77–3.23 Å. In the fourteenth Cu+1.18+ site, Cu+1.18+ is bonded to three equivalent Cu+1.18+ and four Se2- atoms to form distorted CuCu3Se4 tetrahedra that share corners with nine CuSe4 tetrahedra, edges with nine CuCu3Se4 tetrahedra, and faces with three equivalent CuCu3Se4 tetrahedra. There are two shorter (2.47 Å) and one longer (2.49 Å) Cu–Cu bond lengths. There are a spread of Cu–Se bond distances ranging from 2.55–2.65 Å. In the fifteenth Cu+1.18+ site, Cu+1.18+ is bonded in a 12-coordinate geometry to six Cu+1.18+ and six Se2- atoms. There are two shorter (2.51 Å) and one longer (2.55 Å) Cu–Cu bond lengths. There are a spread of Cu–Se bond distances ranging from 2.95–3.06 Å. In the sixteenth Cu+1.18+ site, Cu+1.18+ is bonded to three equivalent Cu+1.18+ and four Se2- atoms to form CuCu3Se4 tetrahedra that share corners with six CuCu3Se4 tetrahedra, a cornercorner with one CuSe4 trigonal pyramid, and edges with nine CuCu3Se4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.56–2.61 Å. In the seventeenth Cu+1.18+ site, Cu+1.18+ is bonded to three equivalent Cu+1.18+ and four Se2- atoms to form distorted CuCu3Se4 tetrahedra that share corners with nine CuSe4 tetrahedra, edges with nine CuCu3Se4 tetrahedra, and faces with three equivalent CuCu3Se4 tetrahedra. There are a spread of Cu–Se bond distances ranging from 2.53–2.69 Å. There are ten inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to ten Cu+1.18+ atoms. In the second Se2- site, Se2- is bonded to four Cu+1.18+ atoms to form SeCu4 tetrahedra that share corners with six equivalent SeCu4 tetrahedra and corners with three equivalent SeCu5 trigonal bipyramids. In the third Se2- site, Se2- is bonded in a distorted body-centered cubic geometry to eight Cu+1.18+ atoms. In the fourth Se2- site, Se2- is bonded to five Cu+1.18+ atoms to form distorted SeCu5 trigonal bipyramids that share corners with three equivalent SeCu4 tetrahedra and corners with six equivalent SeCu5 trigonal bipyramids. In the fifth Se2- site, Se2- is bonded to five Cu+1.18+ atoms to form distorted corner-sharing SeCu5 trigonal bipyramids. In the sixth Se2- site, Se2- is bonded in a 7-coordinate geometry to seven Cu+1.18+ atoms. In the seventh Se2- site, Se2- is bonded in a 7-coordinate geometry to seven Cu+1.18+ atoms. In the eighth Se2- site, Se2- is bonded to four Cu+1.18+ atoms to form corner-sharing SeCu4 trigonal pyramids. In the ninth Se2- site, Se2- is bonded in a 8-coordinate geometry to fourteen Cu+1.18+ atoms. In the tenth Se2- site, Se2- is bonded in a 8-coordinate geometry to eight Cu+1.18+ atoms.