Materials Data on Nb2Hg2O7 by Materials Project

Nb2Hg2O7 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 HgO8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 40°. All Nb–O bond lengths are 2.00 Å. Hg2+ is bonded to eight O2- atoms to form distorted HgO8 hexagonal bipyramids that share edges with six equivalent HgO8 hexagonal bipyramids and edges with six equivalent NbO6 octahedra. There are two shorter (2.31 Å) and six longer (2.73 Å) Hg–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent Hg2+ atoms to form corner-sharing OHg4 tetrahedra. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and two equivalent Hg2+ atoms.