Materials Data on Ca6Al7O16 by Materials Project

Abstract

Ca6Al7O16 is Hausmannite-derived structured and crystallizes in the cubic I-43d space group. The structure is three-dimensional. Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.53 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four equivalent O atoms to form corner-sharing AlO4 tetrahedra. All Al–O bond lengths are 1.76 Å. In the second Al site, Al is bonded to four O atoms to form corner-sharing AlO4 tetrahedra. There is one shorter (1.74 Å) and three longer (1.80 Å) Al–O bond length. There are two inequivalent O sites. In the first O site, O is bonded to three equivalent Ca and one Al atom to form distorted OCa3Al tetrahedra that share corners with three equivalent OCa3Al tetrahedra, corners with nine equivalent OCa2Al2 trigonal pyramids, and edges with three equivalent OCa2Al2 trigonal pyramids. In the second O site, O is bonded to two equivalent Ca and two Al atoms to form distorted OCa2Al2 trigonal pyramids that share corners with three equivalent OCa3Al tetrahedra, corners with five equivalent OCa2Al2 trigonal pyramids, an edgeedge with one OCa3Al tetrahedra, and edges with three equivalent OCa2Al2 trigonal pyramids.