Materials Data on Al2Cr3CuS8 by Materials Project

Cr3CuAl2S8 is Spinel-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. Cr3+ is bonded to six S2- atoms to form CrS6 octahedra that share corners with three equivalent CuS4 tetrahedra, corners with three equivalent AlS4 tetrahedra, edges with two equivalent AlS6 octahedra, and edges with four equivalent CrS6 octahedra. There are three shorter (2.37 Å) and three longer (2.46 Å) Cr–S bond lengths. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with three equivalent AlS6 octahedra and corners with nine equivalent CrS6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are three shorter (2.30 Å) and one longer (2.31 Å) Cu–S bond lengths. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six S2- atoms to form AlS6 octahedra that share corners with three equivalent CuS4 tetrahedra, corners with three equivalent AlS4 tetrahedra, and edges with six equivalent CrS6 octahedra. There are three shorter (2.37 Å) and three longer (2.47 Å) Al–S bond lengths. In the second Al3+ site, Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with three equivalent AlS6 octahedra and corners with nine equivalent CrS6 octahedra. The corner-sharing octahedral tilt angles are 59°. There are one shorter (2.29 Å) and three longer (2.30 Å) Al–S bond lengths. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Cr3+ and two Al3+ atoms to form a mixture of distorted corner and edge-sharing SAl2Cr2 trigonal pyramids. In the second S2- site, S2- is bonded to three equivalent Cr3+ and one Al3+ atom to form a mixture of distorted corner and edge-sharing SAlCr3 trigonal pyramids. In the third S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Cr3+, one Cu1+, and one Al3+ atom. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Cr3+ and one Cu1+ atom.