Materials Data on CaAl2(OF)4 by Materials Project

Abstract

CaAl2(OF)4 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Ca is bonded in a 8-coordinate geometry to two equivalent O and six F atoms. Both Ca–O bond lengths are 2.77 Å. There are a spread of Ca–F bond distances ranging from 2.25–2.54 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to four O and two equivalent F atoms to form edge-sharing AlO4F2 octahedra. There is two shorter (1.87 Å) and two longer (1.88 Å) Al–O bond length. Both Al–F bond lengths are 1.88 Å. In the second Al site, Al is bonded to four O and two equivalent F atoms to form distorted edge-sharing AlO4F2 octahedra. There is two shorter (1.90 Å) and two longer (1.92 Å) Al–O bond length. Both Al–F bond lengths are 1.77 Å. There are two inequivalent O sites. In the first O site, O is bonded in a distorted water-like geometry to one Ca and two Al atoms. In the second O site, O is bonded in a bent 120 degrees geometry to two Al atoms. There are two inequivalent F sites. In the first F site, F is bonded in a bent 150 degrees geometry to one Ca and one Al atom. In the second F site, F is bonded in a 3-coordinate geometry to two equivalent Ca and one Al atom.