Materials Data on Gd3MgAlS7 by Materials Project

Abstract

MgGd3AlS7 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. Mg2+ is bonded to six equivalent S2- atoms to form MgS6 octahedra that share corners with three equivalent GdS7 pentagonal bipyramids, edges with three equivalent GdS7 pentagonal bipyramids, faces with two equivalent MgS6 octahedra, and faces with three equivalent GdS7 pentagonal bipyramids. There are three shorter (2.54 Å) and three longer (2.61 Å) Mg–S bond lengths. Gd3+ is bonded to seven S2- atoms to form distorted GdS7 pentagonal bipyramids that share a cornercorner with one MgS6 octahedra, corners with six equivalent GdS7 pentagonal bipyramids, corners with two equivalent AlS4 tetrahedra, an edgeedge with one MgS6 octahedra, edges with four equivalent GdS7 pentagonal bipyramids, an edgeedge with one AlS4 tetrahedra, and a faceface with one MgS6 octahedra. The corner-sharing octahedral tilt angles are 28°. There are a spread of Gd–S bond distances ranging from 2.78–2.98 Å. Al3+ is bonded to four S2- atoms to form AlS4 tetrahedra that share corners with six equivalent GdS7 pentagonal bipyramids and edges with three equivalent GdS7 pentagonal bipyramids. There are one shorter (2.24 Å) and three longer (2.25 Å) Al–S bond lengths. There are three inequivalent S2- sites. In the first S2- site, S2- is bonded to three equivalent Gd3+ and one Al3+ atom to form distorted corner-sharing SGd3Al tetrahedra. In the second S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Gd3+ and one Al3+ atom. In the third S2- site, S2- is bonded to two equivalent Mg2+ and three equivalent Gd3+ atoms to form distorted SGd3Mg2 square pyramids that share corners with two equivalent SGd3Mg2 square pyramids, corners with three equivalent SGd3Al tetrahedra, edges with four equivalent SGd3Mg2 square pyramids, and faces with two equivalent SGd3Mg2 square pyramids.