DOI: 10.17188/1283137
title: Materials Data on Sr4Nb2O9 by Materials Project

description: Sr4Nb2O9 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.41–2.80 Å. In the second Sr2+ site, Sr2+ is bonded to seven O2- atoms to form SrO7 pentagonal bipyramids that share corners with three equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 15–33°. There are a spread of Sr–O bond distances ranging from 2.44–2.68 Å. In the third Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.42–3.15 Å. In the fourth Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sr–O bond distances ranging from 2.39–2.83 Å. In the fifth Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sr–O bond distances ranging from 2.49–2.87 Å. In the sixth Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.43–3.18 Å. In the seventh Sr2+ site, Sr2+ is bonded to six O2- atoms to form distorted SrO6 pentagonal pyramids that share corners with three equivalent NbO6 octahedra and corners with three equivalent NbO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 8–25°. There are a spread of Sr–O bond distances ranging from 2.41–2.56 Å. In the eighth Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.52–2.99 Å. There are four inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent SrO7 pentagonal bipyramids and corners with three equivalent SrO6 pentagonal pyramids. There are a spread of Nb–O bond distances ranging from 1.98–2.14 Å. In the second Nb5+ site, Nb5+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Nb–O bond distances ranging from 1.88–2.26 Å. In the third Nb5+ site, Nb5+ is bonded to five O2- atoms to form distorted NbO5 trigonal bipyramids that share corners with three equivalent SrO6 pentagonal pyramids and a cornercorner with one NbO4 tetrahedra. There are a spread of Nb–O bond distances ranging from 1.86–2.37 Å. In the fourth Nb5+ site, Nb5+ is bonded to four O2- atoms to form corner-sharing NbO4 tetrahedra. There are a spread of Nb–O bond distances ranging from 1.84–1.92 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Nb5+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Sr2+ and one Nb5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Nb5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Nb5+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to two Sr2+ and one Nb5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Nb5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Nb5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Nb5+ atom. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two Sr2+ and one Nb5+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Sr2+ and one Nb5+ atom. In the eleventh O2- site, O2- is bonded in a 5-coordinate geometry to four Sr2+ and one Nb5+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Sr2+ and two Nb5+ atoms. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Sr2+ and two Nb5+ atoms. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Nb5+ atom. In the fifteenth O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Sr2+ and one Nb5+ atom. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to four Sr2+ and one Nb5+ atom. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Nb5+ atom. In the eighteenth O2- site, O2- is bonded in a 5-coordinate geometry to four Sr2+ and one Nb5+ atom.