Materials Data on CaAl4O7 by Materials Project
CaAl4O7 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.45 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.74–1.82 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form corner-sharing AlO4 tetrahedra. There are a spread of Al–O bond distances ranging from 1.75–1.81 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to three Al3+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Al3+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two equivalent Al3+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two equivalent Al3+ atoms.