Materials Data on KTb3F12 by Materials Project
KTb3F12 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. K1+ is bonded in a distorted cuboctahedral geometry to twelve F1- atoms. There are four shorter (2.74 Å) and eight longer (3.15 Å) K–F bond lengths. There are two inequivalent Tb+3.67+ sites. In the first Tb+3.67+ site, Tb+3.67+ is bonded in a 8-coordinate geometry to eight F1- atoms. There are four shorter (2.26 Å) and four longer (2.34 Å) Tb–F bond lengths. In the second Tb+3.67+ site, Tb+3.67+ is bonded in a body-centered cubic geometry to eight equivalent F1- atoms. All Tb–F bond lengths are 2.29 Å. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted bent 150 degrees geometry to one K1+ and two Tb+3.67+ atoms. In the second F1- site, F1- is bonded in a trigonal planar geometry to one K1+ and two equivalent Tb+3.67+ atoms.