Materials Data on TmF3 by Materials Project
TmF3 is alpha bismuth trifluoride structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tm3+ is bonded to twelve F1- atoms to form a mixture of corner, edge, and face-sharing TmF12 cuboctahedra. There are eight shorter (2.41 Å) and four longer (2.55 Å) Tm–F bond lengths. There are two inequivalent F1- sites. In the first F1- site, F1- is bonded to four equivalent Tm3+ atoms to form a mixture of distorted corner and edge-sharing FTm4 tetrahedra. In the second F1- site, F1- is bonded in a distorted square co-planar geometry to four equivalent Tm3+ atoms.