DOE OSTI2020
Cu2FeZr3S8 is Spinel-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Zr4+ is bonded to six S2- atoms to form ZrS6 octahedra that share corners with six equivalent CuS4 tetrahedra, edges with two equivalent FeS6 octahedra, and edges with four equivalent ZrS6 octahedra. There are two shorter (2.55 Å) and four longer (2.58 Å) Zr–S bond lengths. Fe2+ is bonded to six equivalent S2- atoms to form FeS6 octahedra that share corners with six equivalent CuS4 tetrahedra and edges with six equivalent ZrS6 octahedra. All Fe–S bond lengths are 2.41 Å. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with three equivalent FeS6 octahedra and corners with nine equivalent ZrS6 octahedra. The corner-sharing octahedra tilt angles range from 48–60°. There are one shorter (2.26 Å) and three longer (2.30 Å) Cu–S bond lengths. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a rectangular see-saw-like geometry to three equivalent Zr4+ and one Cu1+ atom. In the second S2- site, S2- is bonded in a rectangular see-saw-like geometry to two equivalent Zr4+, one Fe2+, and one Cu1+ atom.