Materials Data on Nb8Tl8O25 by Materials Project
Nb8Tl8O25 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are six inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with four TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 38–39°. There are four shorter (2.02 Å) and two longer (2.03 Å) Nb–O bond lengths. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with two TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 38–39°. There are four shorter (2.02 Å) and two longer (2.03 Å) Nb–O bond lengths. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with two equivalent TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Nb–O bond distances ranging from 2.01–2.03 Å. In the fourth Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with four TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 38–39°. There are three shorter (2.02 Å) and three longer (2.03 Å) Nb–O bond lengths. In the fifth Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 38–39°. There are five shorter (2.02 Å) and one longer (2.03 Å) Nb–O bond lengths. In the sixth Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and edges with six TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 38–39°. There are three shorter (2.01 Å) and three longer (2.03 Å) Nb–O bond lengths. There are six inequivalent Tl+1.25+ sites. In the first Tl+1.25+ site, Tl+1.25+ is bonded in a hexagonal planar geometry to six O2- atoms. There are a spread of Tl–O bond distances ranging from 2.77–2.83 Å. In the second Tl+1.25+ site, Tl+1.25+ is bonded to seven O2- atoms to form distorted TlO7 hexagonal pyramids that share corners with two TlO7 hexagonal pyramids, edges with three TlO7 hexagonal pyramids, and edges with six NbO6 octahedra. There are a spread of Tl–O bond distances ranging from 2.39–2.80 Å. In the third Tl+1.25+ site, Tl+1.25+ is bonded to seven O2- atoms to form distorted TlO7 hexagonal pyramids that share corners with two equivalent TlO7 hexagonal pyramids, edges with three TlO7 hexagonal pyramids, and edges with six NbO6 octahedra. There are a spread of Tl–O bond distances ranging from 2.39–2.80 Å. In the fourth Tl+1.25+ site, Tl+1.25+ is bonded to seven O2- atoms to form distorted TlO7 hexagonal pyramids that share edges with three TlO7 hexagonal pyramids and edges with six NbO6 octahedra. There are a spread of Tl–O bond distances ranging from 2.37–2.80 Å. In the fifth Tl+1.25+ site, Tl+1.25+ is bonded in a hexagonal planar geometry to six O2- atoms. There are a spread of Tl–O bond distances ranging from 2.78–2.83 Å. In the sixth Tl+1.25+ site, Tl+1.25+ is bonded in a hexagonal planar geometry to six O2- atoms. There are a spread of Tl–O bond distances ranging from 2.78–2.83 Å. There are seventeen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two Tl+1.25+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two equivalent Tl+1.25+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two Tl+1.25+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two Tl+1.25+ atoms. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and two Tl+1.25+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and two Tl+1.25+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb5+ and two Tl+1.25+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb5+ and two Tl+1.25+ atoms. In the ninth O2- site, O2- is bonded in a tetrahedral geometry to four Tl+1.25+ atoms. In the tenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb5+ and two Tl+1.25+ atoms. In the eleventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb5+ and two equivalent Tl+1.25+ atoms. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Nb5+ and two equivalent Tl+1.25+ atoms. In the thirteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two Tl+1.25+ atoms. In the fourteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two Tl+1.25+ atoms. In the fifteenth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Nb5+ and two Tl+1.25+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Nb5+ and two Tl+1.25+ atoms. In the seventeenth O2- site, O2- is bonded in a 2-coordinate geometry to two Nb5+ and two equivalent Tl+1.25+ atoms.