Materials Data on Nb2Tl2O7 by Materials Project
Nb2Tl2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Nb5+ is bonded to six equivalent O2- atoms to form NbO6 octahedra that share corners with six equivalent NbO6 octahedra and edges with six equivalent TlO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. All Nb–O bond lengths are 2.02 Å. Tl2+ is bonded to eight O2- atoms to form distorted TlO8 hexagonal bipyramids that share edges with six equivalent TlO8 hexagonal bipyramids and edges with six equivalent NbO6 octahedra. There are two shorter (2.33 Å) and six longer (2.78 Å) Tl–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and two equivalent Tl2+ atoms. In the second O2- site, O2- is bonded to four equivalent Tl2+ atoms to form corner-sharing OTl4 tetrahedra.