Materials Data on Ba2AlCuF9 by Materials Project
Ba2CuAlF9 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of Ba–F bond distances ranging from 2.66–3.13 Å. In the second Ba2+ site, Ba2+ is bonded in a 11-coordinate geometry to eleven F1- atoms. There are a spread of Ba–F bond distances ranging from 2.66–3.15 Å. Cu2+ is bonded to five F1- atoms to form distorted CuF5 trigonal bipyramids that share corners with two equivalent AlF6 octahedra. The corner-sharing octahedra tilt angles range from 38–46°. There are a spread of Cu–F bond distances ranging from 1.89–2.07 Å. Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with two equivalent CuF5 trigonal bipyramids. There are a spread of Al–F bond distances ranging from 1.77–1.89 Å. There are nine inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted single-bond geometry to three Ba2+ and one Cu2+ atom. In the second F1- site, F1- is bonded in a distorted single-bond geometry to two Ba2+ and one Al3+ atom. In the third F1- site, F1- is bonded in a 1-coordinate geometry to three Ba2+ and one Cu2+ atom. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to three Ba2+ and one Al3+ atom. In the fifth F1- site, F1- is bonded in a 3-coordinate geometry to two equivalent Ba2+ and one Cu2+ atom. In the sixth F1- site, F1- is bonded in a distorted single-bond geometry to two equivalent Ba2+ and one Al3+ atom. In the seventh F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Ba2+, one Cu2+, and one Al3+ atom. In the eighth F1- site, F1- is bonded in a distorted single-bond geometry to two equivalent Ba2+ and one Al3+ atom. In the ninth F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Cu2+, and one Al3+ atom.