Materials Data on Gd2Al6Si4Au by Materials Project

Abstract

Gd2AuAl6Si4 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Gd is bonded to six Si atoms to form distorted GdSi6 octahedra that share corners with twelve AlSiAu3 tetrahedra, edges with six equivalent GdSi6 octahedra, and edges with six AlSi4 tetrahedra. There are three shorter (2.98 Å) and three longer (2.99 Å) Gd–Si bond lengths. Au is bonded in a body-centered cubic geometry to eight Al atoms. There are six shorter (2.58 Å) and two longer (2.64 Å) Au–Al bond lengths. There are three inequivalent Al sites. In the first Al site, Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent GdSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent GdSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–55°. There are one shorter (2.51 Å) and three longer (2.52 Å) Al–Si bond lengths. In the second Al site, Al is bonded to one Au and three equivalent Si atoms to form AlSi3Au tetrahedra that share corners with three equivalent GdSi6 octahedra, corners with ten AlSiAu3 tetrahedra, edges with three equivalent GdSi6 octahedra, and edges with three equivalent AlSiAu3 tetrahedra. The corner-sharing octahedral tilt angles are 18°. All Al–Si bond lengths are 2.56 Å. In the third Al site, Al is bonded to three equivalent Au and one Si atom to form AlSiAu3 tetrahedra that share corners with three equivalent GdSi6 octahedra, corners with twelve AlSiAu3 tetrahedra, and edges with six AlSiAu3 tetrahedra. The corner-sharing octahedral tilt angles are 55°. The Al–Si bond length is 2.54 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded to three equivalent Gd and four Al atoms to form a mixture of distorted edge and corner-sharing SiGd3Al4 pentagonal bipyramids. In the second Si site, Si is bonded to three equivalent Gd and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SiGd3Al4 pentagonal bipyramids.