Materials Data on KCaAl2F9 by Materials Project
KCaAl2F9 crystallizes in the orthorhombic C222_1 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of K–F bond distances ranging from 2.76–3.09 Å. In the second K1+ site, K1+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of K–F bond distances ranging from 2.80–3.08 Å. There are two inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six F1- atoms to form distorted CaF6 octahedra that share corners with six AlF6 octahedra. The corner-sharing octahedra tilt angles range from 28–61°. There are a spread of Ca–F bond distances ranging from 2.22–2.38 Å. In the second Ca2+ site, Ca2+ is bonded to six F1- atoms to form distorted CaF6 octahedra that share corners with six AlF6 octahedra. The corner-sharing octahedra tilt angles range from 19–61°. There are a spread of Ca–F bond distances ranging from 2.18–2.38 Å. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with three equivalent CaF6 octahedra and corners with three AlF6 octahedra. The corner-sharing octahedra tilt angles range from 21–60°. There are a spread of Al–F bond distances ranging from 1.80–1.89 Å. In the second Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with three CaF6 octahedra and corners with three AlF6 octahedra. The corner-sharing octahedra tilt angles range from 21–61°. There are a spread of Al–F bond distances ranging from 1.80–1.89 Å. In the third Al3+ site, Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with three CaF6 octahedra and corners with three AlF6 octahedra. The corner-sharing octahedra tilt angles range from 17–61°. There are a spread of Al–F bond distances ranging from 1.79–1.86 Å. There are fourteen inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one Ca2+ and one Al3+ atom. In the second F1- site, F1- is bonded in a 1-coordinate geometry to two K1+, one Ca2+, and one Al3+ atom. In the third F1- site, F1- is bonded in a 1-coordinate geometry to two K1+, one Ca2+, and one Al3+ atom. In the fourth F1- site, F1- is bonded in a bent 150 degrees geometry to two equivalent Al3+ atoms. In the fifth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+, one Ca2+, and one Al3+ atom. In the sixth F1- site, F1- is bonded in a linear geometry to two equivalent Al3+ atoms. In the seventh F1- site, F1- is bonded in a 1-coordinate geometry to two equivalent K1+, one Ca2+, and one Al3+ atom. In the eighth F1- site, F1- is bonded in a 1-coordinate geometry to two K1+, one Ca2+, and one Al3+ atom. In the ninth F1- site, F1- is bonded in a 1-coordinate geometry to two equivalent K1+, one Ca2+, and one Al3+ atom. In the tenth F1- site, F1- is bonded in a bent 150 degrees geometry to two Al3+ atoms. In the eleventh F1- site, F1- is bonded in a bent 150 degrees geometry to one K1+ and two Al3+ atoms. In the twelfth F1- site, F1- is bonded in a 1-coordinate geometry to two K1+, one Ca2+, and one Al3+ atom. In the thirteenth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+, one Ca2+, and one Al3+ atom. In the fourteenth F1- site, F1- is bonded in a bent 150 degrees geometry to two Al3+ atoms.