Materials Data on SrAl4O7 by Materials Project

Abstract

SrAl4O7 crystallizes in the orthorhombic Cmme space group. The structure is three-dimensional. Sr2+ is bonded in a distorted q6 geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.79–3.09 Å. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with three AlO4 tetrahedra, and an edgeedge with one AlO6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are a spread of Al–O bond distances ranging from 1.72–1.78 Å. In the second Al3+ site, Al3+ is bonded to four equivalent O2- atoms to form AlO4 tetrahedra that share corners with four equivalent AlO6 octahedra and corners with four equivalent AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. All Al–O bond lengths are 1.77 Å. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing AlO6 octahedra. There is two shorter (1.86 Å) and four longer (2.08 Å) Al–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+ and three Al3+ atoms. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two equivalent Sr2+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Sr2+ and two equivalent Al3+ atoms.