Materials Data on TmSeF by Materials Project
TmSeF crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Tm3+ sites. In the first Tm3+ site, Tm3+ is bonded to two equivalent Se2- and six equivalent F1- atoms to form TmSe2F6 hexagonal bipyramids that share corners with six equivalent TmSe6 octahedra and edges with six equivalent TmSe2F6 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 56°. Both Tm–Se bond lengths are 2.84 Å. All Tm–F bond lengths are 2.34 Å. In the second Tm3+ site, Tm3+ is bonded to six equivalent Se2- atoms to form TmSe6 octahedra that share corners with six equivalent TmSe2F6 hexagonal bipyramids and edges with six equivalent TmSe6 octahedra. All Tm–Se bond lengths are 2.82 Å. Se2- is bonded in a distorted rectangular see-saw-like geometry to four Tm3+ atoms. F1- is bonded in a trigonal planar geometry to three equivalent Tm3+ atoms.