Materials Data on K3ErF6 by Materials Project
K3ErF6 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 ErF6 octahedra. The corner-sharing octahedra tilt angles range from 32–37°. There are a spread of K–F bond distances ranging from 2.60–2.66 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 2.68–3.34 Å. Er3+ is bonded to six F1- atoms to form ErF6 octahedra that share corners with six equivalent KF6 octahedra. The corner-sharing octahedra tilt angles range from 32–37°. There are two shorter (2.16 Å) and four longer (2.17 Å) Er–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 Er3+ atom. In the second F1- site, F1- is bonded to three K1+ and one Er3+ atom to form distorted corner-sharing FK3Er tetrahedra. In the third F1- site, F1- is bonded in a 5-coordinate geometry to four K1+ and one Er3+ atom.