Materials Data on ThTa2O7 by Materials Project
ThTa2O7 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Th4+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Th–O bond distances ranging from 2.40–2.85 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with two equivalent TaO6 octahedra, a cornercorner with one TaO7 pentagonal bipyramid, an edgeedge with one TaO6 octahedra, and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 22°. There are a spread of Ta–O bond distances ranging from 1.93–2.12 Å. In the second Ta5+ site, Ta5+ is bonded to seven O2- atoms to form TaO7 pentagonal bipyramids that share a cornercorner with one TaO6 octahedra, corners with two equivalent TaO7 pentagonal bipyramids, an edgeedge with one TaO6 octahedra, and an edgeedge with one TaO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ta–O bond distances ranging from 1.98–2.21 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ta5+ atoms. In the second O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Th4+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Th4+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one Th4+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded to three equivalent Th4+ and one Ta5+ atom to form a mixture of distorted edge and corner-sharing OTh3Ta tetrahedra. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent Th4+ and one Ta5+ atom. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Th4+ and two Ta5+ atoms.