Materials Data on Sr3Ta4(O6F)2 by Materials Project

Abstract

Sr3Ta4(O6F)2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sr2+ is bonded to six O2- and two equivalent F1- atoms to form distorted SrO6F2 hexagonal bipyramids that share edges with four equivalent SrO6F2 hexagonal bipyramids and edges with six TaO6 octahedra. There are two shorter (2.70 Å) and four longer (2.73 Å) Sr–O bond lengths. Both Sr–F bond lengths are 2.33 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and edges with four equivalent SrO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–42°. All Ta–O bond lengths are 2.01 Å. In the second Ta5+ site, Ta5+ is bonded to six equivalent O2- atoms to form TaO6 octahedra that share corners with six equivalent TaO6 octahedra and edges with six equivalent SrO6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. All Ta–O bond lengths are 2.00 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+ and two Ta5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Sr2+ and two equivalent Ta5+ atoms. F1- is bonded in a trigonal non-coplanar geometry to three equivalent Sr2+ atoms.