Materials Data on Cu7As6Se13 by Materials Project
Cu7As6Se13 crystallizes in the trigonal R3 space group. The structure is three-dimensional. there are three inequivalent Cu+1.71+ sites. In the first Cu+1.71+ site, Cu+1.71+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with five CuSe4 tetrahedra and corners with three equivalent AsSe4 trigonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.41–2.49 Å. In the second Cu+1.71+ site, Cu+1.71+ is bonded to four Se2- atoms to form CuSe4 tetrahedra that share corners with five CuSe4 tetrahedra and corners with three equivalent AsSe4 trigonal pyramids. There are a spread of Cu–Se bond distances ranging from 2.40–2.47 Å. In the third Cu+1.71+ site, Cu+1.71+ is bonded in a rectangular see-saw-like geometry to four Se2- atoms. There are one shorter (2.48 Å) and three longer (2.52 Å) Cu–Se bond lengths. There are two inequivalent As+2.33+ sites. In the first As+2.33+ site, As+2.33+ is bonded to four Se2- atoms to form distorted AsSe4 trigonal pyramids that share corners with six CuSe4 tetrahedra and corners with two equivalent AsSe4 trigonal pyramids. There are a spread of As–Se bond distances ranging from 2.41–3.05 Å. In the second As+2.33+ site, As+2.33+ is bonded in a distorted trigonal non-coplanar geometry to three Se2- atoms. There are a spread of As–Se bond distances ranging from 2.44–2.51 Å. There are five inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two Cu+1.71+ and two equivalent As+2.33+ atoms to form distorted corner-sharing SeCu2As2 tetrahedra. In the second Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to one Cu+1.71+ and two As+2.33+ atoms. In the third Se2- site, Se2- is bonded to three Cu+1.71+ and one As+2.33+ atom to form distorted corner-sharing SeCu3As tetrahedra. In the fourth Se2- site, Se2- is bonded in a 4-coordinate geometry to two Cu+1.71+ and two As+2.33+ atoms. In the fifth Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four Cu+1.71+ atoms.