Materials Data on Cu4Si2NiS7 by Materials Project
Cu4NiSi2S7 is Stannite-like structured and crystallizes in the monoclinic C2 space group. The structure is three-dimensional. Ni2+ is bonded to four S2- atoms to form NiS4 tetrahedra that share corners with four equivalent SiS4 tetrahedra and corners with eight CuS4 tetrahedra. There are two shorter (2.25 Å) and two longer (2.26 Å) Ni–S bond lengths. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share a cornercorner with one NiS4 tetrahedra, corners with five equivalent SiS4 tetrahedra, and corners with six CuS4 tetrahedra. There are a spread of Cu–S bond distances ranging from 2.27–2.34 Å. In the second Cu1+ site, Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with three equivalent NiS4 tetrahedra, corners with four equivalent SiS4 tetrahedra, and corners with five CuS4 tetrahedra. There are one shorter (2.29 Å) and three longer (2.30 Å) Cu–S bond lengths. Si4+ is bonded to four S2- atoms to form SiS4 tetrahedra that share a cornercorner with one SiS4 tetrahedra, corners with two equivalent NiS4 tetrahedra, and corners with nine CuS4 tetrahedra. There are a spread of Si–S bond distances ranging from 2.13–2.25 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to three Cu1+ and one Si4+ atom to form corner-sharing SCu3Si tetrahedra. In the second S2- site, S2- is bonded to one Ni2+, two equivalent Cu1+, and one Si4+ atom to form corner-sharing SCu2SiNi tetrahedra. In the third S2- site, S2- is bonded to one Ni2+, two Cu1+, and one Si4+ atom to form corner-sharing SCu2SiNi tetrahedra. In the fourth S2- site, S2- is bonded to two equivalent Cu1+ and two equivalent Si4+ atoms to form corner-sharing SCu2Si2 tetrahedra.