Materials Data on NdNb3O9 by Materials Project
NdNb3O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Nd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.45–2.57 Å. There are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 28–52°. There are a spread of Nb–O bond distances ranging from 1.87–2.25 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 28–46°. There are a spread of Nb–O bond distances ranging from 1.86–2.25 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 31–52°. There are a spread of Nb–O bond distances ranging from 1.82–2.20 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Nd3+ and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Nd3+ and two Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Nd3+ and two Nb5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Nd3+ and two Nb5+ atoms. In the seventh O2- site, O2- is bonded to two equivalent Nd3+ and two equivalent Nb5+ atoms to form distorted edge-sharing ONd2Nb2 tetrahedra. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Nd3+ and two Nb5+ atoms. In the ninth O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms.