Materials Data on Sr6Nb7O21 by Materials Project
Sr6Nb7O21 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are six inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.78–2.94 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.80–2.92 Å. In the third Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.79–2.95 Å. In the fourth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.79–2.92 Å. In the fifth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.74–2.93 Å. In the sixth Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with ten SrO12 cuboctahedra, faces with five SrO12 cuboctahedra, and faces with eight NbO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.78–2.91 Å. There are seven inequivalent Nb+4.29+ sites. In the first Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of Nb–O bond distances ranging from 2.02–2.06 Å. In the second Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Nb–O bond distances ranging from 2.01–2.06 Å. In the third Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of Nb–O bond distances ranging from 2.02–2.06 Å. In the fourth Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of Nb–O bond distances ranging from 2.01–2.06 Å. In the fifth Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–6°. There are a spread of Nb–O bond distances ranging from 2.02–2.06 Å. In the sixth Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–7°. There are a spread of Nb–O bond distances ranging from 2.01–2.06 Å. In the seventh Nb+4.29+ site, Nb+4.29+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with six SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–6°. There are one shorter (2.03 Å) and five longer (2.04 Å) Nb–O bond lengths. There are twenty-one inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the third O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the fifth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the sixth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the seventh O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the eighth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the ninth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the tenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the eleventh O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the twelfth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the seventeenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two Nb+4.29+ atoms. In the nineteenth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the twentieth O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms. In the twenty-first O2- site, O2- is bonded in a distorted linear geometry to three Sr2+ and two Nb+4.29+ atoms.