Materials Data on SrAl2O4 by Materials Project

Abstract

SrAl2O4 crystallizes in the hexagonal P6_3 space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are three shorter (2.47 Å) and three longer (2.73 Å) Sr–O bond lengths. In the second Sr2+ site, Sr2+ is bonded to six O2- atoms to form SrO6 octahedra that share corners with twelve AlO4 tetrahedra. There are three shorter (2.54 Å) and three longer (2.68 Å) Sr–O bond lengths. In the third Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.57–3.03 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent SrO6 octahedra and corners with four equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 62–70°. There is three shorter (1.77 Å) and one longer (1.78 Å) Al–O bond length. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with two equivalent SrO6 octahedra and corners with four equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–76°. There is two shorter (1.77 Å) and two longer (1.78 Å) Al–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Sr2+ and two Al3+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Sr2+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Sr2+ and two Al3+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+ and two Al3+ atoms.