DOE OSTI2020
KAlF4 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to seven F1- atoms. There are a spread of K–F bond distances ranging from 2.66–3.07 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six F1- atoms. There are a spread of K–F bond distances ranging from 2.67–2.69 Å. There are two inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six F1- atoms to form corner-sharing AlF6 octahedra. The corner-sharing octahedra tilt angles range from 9–21°. There is two shorter (1.78 Å) and four longer (1.87 Å) Al–F bond length. In the second Al3+ site, Al3+ is bonded to six F1- atoms to form corner-sharing AlF6 octahedra. The corner-sharing octahedra tilt angles range from 9–20°. There is two shorter (1.78 Å) and four longer (1.87 Å) Al–F bond length. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Al3+ atoms. In the second F1- site, F1- is bonded in a distorted single-bond geometry to three K1+ and one Al3+ atom. In the third F1- site, F1- is bonded in a distorted single-bond geometry to three K1+ and one Al3+ atom. In the fourth F1- site, F1- is bonded in a linear geometry to two Al3+ atoms. In the fifth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and two equivalent Al3+ atoms.