Materials Data on KAlCuF6 by Materials Project
KCuAlF6 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. K1+ is bonded in a 10-coordinate geometry to ten F1- atoms. There are a spread of K–F bond distances ranging from 2.87–3.19 Å. Cu2+ is bonded to six F1- atoms to form distorted CuF6 octahedra that share corners with two equivalent CuF6 octahedra and corners with four equivalent AlF6 octahedra. The corner-sharing octahedra tilt angles range from 50–62°. There are a spread of Cu–F bond distances ranging from 1.89–2.20 Å. Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with two equivalent AlF6 octahedra and corners with four equivalent CuF6 octahedra. The corner-sharing octahedra tilt angles range from 29–62°. There are a spread of Al–F bond distances ranging from 1.81–1.85 Å. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a 2-coordinate geometry to two equivalent K1+, one Cu2+, and one Al3+ atom. In the second F1- site, F1- is bonded in a 1-coordinate geometry to two equivalent K1+, one Cu2+, and one Al3+ atom. In the third F1- site, F1- is bonded in a distorted bent 120 degrees geometry to one K1+ and two equivalent Cu2+ atoms. In the fourth F1- site, F1- is bonded in a bent 150 degrees geometry to one K1+ and two equivalent Al3+ atoms.