Materials Data on Nb8Pb6O25 by Materials Project
Nb8Pb6O25 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are four inequivalent Nb+4.75+ sites. In the first Nb+4.75+ site, Nb+4.75+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with four PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 36–43°. There are a spread of Nb–O bond distances ranging from 1.97–2.06 Å. In the second Nb+4.75+ site, Nb+4.75+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with four PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 36–43°. There are a spread of Nb–O bond distances ranging from 1.97–2.06 Å. In the third Nb+4.75+ site, Nb+4.75+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with two PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 32–45°. There are a spread of Nb–O bond distances ranging from 1.95–2.08 Å. In the fourth Nb+4.75+ site, Nb+4.75+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with two PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 36–45°. There are a spread of Nb–O bond distances ranging from 1.94–2.09 Å. There are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded to seven O2- atoms to form distorted PbO7 hexagonal pyramids that share a cornercorner with one PbO7 hexagonal pyramid, edges with three PbO7 hexagonal pyramids, and edges with six NbO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.37–2.74 Å. In the second Pb2+ site, Pb2+ is bonded to seven O2- atoms to form distorted PbO7 hexagonal pyramids that share a cornercorner with one PbO7 hexagonal pyramid, edges with three PbO7 hexagonal pyramids, and edges with six NbO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.36–2.77 Å. In the third Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.65–2.91 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Nb+4.75+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb+4.75+ and one Pb2+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb+4.75+ and two equivalent Pb2+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb+4.75+ and two Pb2+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb+4.75+ and two Pb2+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb+4.75+ and one Pb2+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two Nb+4.75+ and two Pb2+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb+4.75+ and two Pb2+ atoms. In the ninth O2- site, O2- is bonded in a tetrahedral geometry to four Pb2+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb+4.75+ and one Pb2+ atom. In the eleventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb+4.75+ and two equivalent Pb2+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb+4.75+ and one Pb2+ atom. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb+4.75+ and two Pb2+ atoms. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb+4.75+ and two equivalent Pb2+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb+4.75+ and one Pb2+ atom.