DOE OSTI2020
Gd3Sc2S7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded to seven S2- atoms to form distorted GdS7 pentagonal bipyramids that share corners with two equivalent GdS6 octahedra, corners with six equivalent ScS6 octahedra, an edgeedge with one ScS6 octahedra, edges with three equivalent GdS6 octahedra, edges with two equivalent GdS7 pentagonal bipyramids, and faces with two equivalent GdS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 23–72°. There are a spread of Gd–S bond distances ranging from 2.77–3.07 Å. In the second Gd3+ site, Gd3+ is bonded to six S2- atoms to form GdS6 octahedra that share corners with two equivalent ScS6 octahedra, corners with four equivalent GdS7 pentagonal bipyramids, edges with two equivalent GdS6 octahedra, and edges with six equivalent GdS7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. There are two shorter (2.72 Å) and four longer (2.73 Å) Gd–S bond lengths. Sc+2.50+ is bonded to six S2- atoms to form ScS6 octahedra that share a cornercorner with one GdS6 octahedra, corners with two equivalent ScS6 octahedra, corners with six equivalent GdS7 pentagonal bipyramids, edges with five equivalent ScS6 octahedra, and an edgeedge with one GdS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 0–50°. There are a spread of Sc–S bond distances ranging from 2.54–2.67 Å. There are four inequivalent S2- sites. In the first S2- site, S2- is bonded to two equivalent Gd3+ and three equivalent Sc+2.50+ atoms to form distorted SGd2Sc3 trigonal bipyramids that share corners with five equivalent SGd3Sc tetrahedra, an edgeedge with one SGd3Sc tetrahedra, and edges with four equivalent SGd2Sc3 trigonal bipyramids. In the second S2- site, S2- is bonded in a 5-coordinate geometry to five Gd3+ atoms. In the third S2- site, S2- is bonded to three Gd3+ and one Sc+2.50+ atom to form distorted SGd3Sc tetrahedra that share corners with three equivalent SGd3Sc tetrahedra, corners with five equivalent SGd2Sc3 trigonal bipyramids, and an edgeedge with one SGd2Sc3 trigonal bipyramid. In the fourth S2- site, S2- is bonded in a square co-planar geometry to four equivalent Sc+2.50+ atoms.