Materials Data on KErBeF6 by Materials Project
KBeErF6 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. K1+ is bonded in a 12-coordinate geometry to twelve F1- atoms. There are a spread of K–F bond distances ranging from 2.77–3.26 Å. Be2+ is bonded in a tetrahedral geometry to four F1- atoms. There are a spread of Be–F bond distances ranging from 1.55–1.58 Å. Er3+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are a spread of Er–F bond distances ranging from 2.23–2.40 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 Be2+, and one Er3+ atom. In the second F1- site, F1- is bonded in a distorted single-bond geometry to one K1+, one Be2+, and one Er3+ atom. In the third F1- site, F1- is bonded to two equivalent K1+ and two equivalent Er3+ atoms to form a mixture of distorted edge and corner-sharing FK2Er2 tetrahedra. In the fourth F1- site, F1- is bonded in a distorted single-bond geometry to three equivalent K1+, one Be2+, and one Er3+ atom.