Materials Data on K3TmF6 by Materials Project
K3TmF6 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded to six F1- atoms to form KF6 octahedra that share corners with six equivalent TmF6 octahedra. The corner-sharing octahedra tilt angles range from 31–37°. There are a spread of K–F bond distances ranging from 2.60–2.65 Å. In the second K1+ site, K1+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of K–F bond distances ranging from 2.68–3.33 Å. Tm3+ is bonded to six F1- atoms to form TmF6 octahedra that share corners with six equivalent KF6 octahedra. The corner-sharing octahedra tilt angles range from 31–37°. There are four shorter (2.15 Å) and two longer (2.16 Å) Tm–F bond lengths. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a 1-coordinate geometry to four K1+ and one Tm3+ atom. In the second F1- site, F1- is bonded to three K1+ and one Tm3+ atom to form distorted corner-sharing FK3Tm tetrahedra. In the third F1- site, F1- is bonded in a 5-coordinate geometry to four K1+ and one Tm3+ atom.