Materials Data on Sr3AlAs3 by Materials Project

Abstract

Sr3AlAs3 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six As3- atoms. There are a spread of Sr–As bond distances ranging from 3.17–3.59 Å. In the second Sr2+ site, Sr2+ is bonded to six As3- atoms to form distorted SrAs6 octahedra that share corners with five equivalent SrAs6 octahedra, corners with four equivalent AlAs4 tetrahedra, edges with eight equivalent SrAs6 octahedra, and a faceface with one AlAs4 tetrahedra. The corner-sharing octahedra tilt angles range from 13–26°. There are a spread of Sr–As bond distances ranging from 3.18–3.51 Å. Al3+ is bonded to four As3- atoms to form AlAs4 tetrahedra that share corners with eight equivalent SrAs6 octahedra, an edgeedge with one AlAs4 tetrahedra, and faces with two equivalent SrAs6 octahedra. The corner-sharing octahedra tilt angles range from 37–55°. There are two shorter (2.50 Å) and two longer (2.51 Å) Al–As bond lengths. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a 8-coordinate geometry to six Sr2+ and two equivalent Al3+ atoms. In the second As3- site, As3- is bonded in a 7-coordinate geometry to six Sr2+ and one Al3+ atom.