Materials Data on Cu8SiSe6 by Materials Project
Cu8SiSe6 crystallizes in the orthorhombic Pmn2_1 space group. The structure is three-dimensional. there are five inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a 4-coordinate geometry to four Se2- atoms. There are a spread of Cu–Se bond distances ranging from 2.37–3.05 Å. In the second Cu1+ site, Cu1+ is bonded in a distorted T-shaped geometry to three Se2- atoms. There are a spread of Cu–Se bond distances ranging from 2.42–2.60 Å. In the third Cu1+ site, Cu1+ is bonded to four Se2- atoms to form distorted CuSe4 tetrahedra that share corners with two equivalent SiSe4 tetrahedra and corners with six equivalent CuSe4 trigonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.41–2.57 Å. In the fourth Cu1+ site, Cu1+ is bonded in a distorted trigonal planar geometry to three Se2- atoms. There are a spread of Cu–Se bond distances ranging from 2.45–2.55 Å. In the fifth Cu1+ site, Cu1+ is bonded to four Se2- atoms to form distorted CuSe4 trigonal pyramids that share corners with two equivalent SiSe4 tetrahedra, corners with three equivalent CuSe4 tetrahedra, a cornercorner with one CuSe4 trigonal pyramid, and an edgeedge with one CuSe4 trigonal pyramid. There are a spread of Cu–Se bond distances ranging from 2.43–2.73 Å. Si4+ is bonded to four Se2- atoms to form SiSe4 tetrahedra that share corners with two equivalent CuSe4 tetrahedra and corners with four equivalent CuSe4 trigonal pyramids. There are a spread of Si–Se bond distances ranging from 2.26–2.28 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to four Cu1+ and one Si4+ atom. In the second Se2- site, Se2- is bonded in a distorted trigonal bipyramidal geometry to five Cu1+ atoms. In the third Se2- site, Se2- is bonded in a 6-coordinate geometry to eight Cu1+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted tetrahedral geometry to three Cu1+ and one Si4+ atom. In the fifth Se2- site, Se2- is bonded in a 6-coordinate geometry to five Cu1+ and one Si4+ atom.