Materials Data on Sr3(AlAs2)2 by Materials Project

Abstract

Sr3Al2As4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to six As3- atoms to form distorted SrAs6 octahedra that share corners with seven SrAs6 octahedra, corners with six equivalent AlAs4 tetrahedra, edges with six equivalent SrAs6 octahedra, edges with three equivalent AlAs4 tetrahedra, and a faceface with one SrAs6 octahedra. The corner-sharing octahedra tilt angles range from 16–62°. There are a spread of Sr–As bond distances ranging from 3.09–3.57 Å. In the second Sr2+ site, Sr2+ is bonded to six As3- atoms to form SrAs6 octahedra that share corners with ten equivalent SrAs6 octahedra, corners with four equivalent AlAs4 tetrahedra, edges with two equivalent SrAs6 octahedra, edges with four equivalent AlAs4 tetrahedra, and faces with two equivalent SrAs6 octahedra. The corner-sharing octahedra tilt angles range from 31–62°. There are a spread of Sr–As bond distances ranging from 3.10–3.26 Å. Al3+ is bonded to four As3- atoms to form AlAs4 tetrahedra that share corners with eight SrAs6 octahedra, corners with two equivalent AlAs4 tetrahedra, edges with five SrAs6 octahedra, and an edgeedge with one AlAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 21–85°. There are a spread of Al–As bond distances ranging from 2.50–2.56 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 7-coordinate geometry to five Sr2+ and two equivalent Al3+ atoms. In the second As3- site, As3- is bonded in a 6-coordinate geometry to four Sr2+ and two equivalent Al3+ atoms.