Materials Data on Y(AlSi)2 by Materials Project
YAl2Si2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Y is bonded to six equivalent Si atoms to form distorted YSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent YSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Y–Si bond lengths are 2.97 Å. Al is bonded to four equivalent Si atoms to form distorted AlSi4 tetrahedra that share corners with six equivalent YSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent YSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–55°. There are three shorter (2.51 Å) and one longer (2.53 Å) Al–Si bond lengths. Si is bonded to three equivalent Y and four equivalent Al atoms to form a mixture of distorted edge and corner-sharing SiY3Al4 pentagonal bipyramids.