DOI: 10.17188/1263212
title: Materials Data on Ca4Nb2O9 by Materials Project

description: Ca4Nb2O9 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are sixteen inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NbO6 octahedra. The corner-sharing octahedra tilt angles range from 31–46°. There are a spread of Ca–O bond distances ranging from 2.27–2.33 Å. In the second Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.75 Å. In the third Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.58 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NbO6 octahedra. The corner-sharing octahedra tilt angles range from 30–45°. There are a spread of Ca–O bond distances ranging from 2.27–2.33 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.96 Å. In the sixth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–3.05 Å. In the seventh Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NbO6 octahedra. The corner-sharing octahedra tilt angles range from 31–43°. There are a spread of Ca–O bond distances ranging from 2.29–2.37 Å. In the eighth Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.23–2.74 Å. In the ninth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.35–2.81 Å. In the tenth Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six NbO6 octahedra. The corner-sharing octahedra tilt angles range from 33–51°. There are a spread of Ca–O bond distances ranging from 2.28–2.37 Å. In the eleventh Ca2+ site, Ca2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.63 Å. In the twelfth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.73 Å. In the thirteenth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.91 Å. In the fourteenth Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.31–2.81 Å. In the fifteenth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.68 Å. In the sixteenth Ca2+ site, Ca2+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.26–2.91 Å. There are eight inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three CaO6 octahedra and corners with three NbO6 octahedra. The corner-sharing octahedra tilt angles range from 31–48°. There are a spread of Nb–O bond distances ranging from 1.92–2.28 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share a cornercorner with one NbO6 octahedra and corners with five CaO6 octahedra. The corner-sharing octahedra tilt angles range from 31–46°. There are a spread of Nb–O bond distances ranging from 1.91–2.46 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two NbO6 octahedra and corners with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 27–43°. There are a spread of Nb–O bond distances ranging from 1.97–2.42 Å. In the fourth Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share a cornercorner with one NbO6 octahedra and corners with five CaO6 octahedra. The corner-sharing octahedra tilt angles range from 32–45°. There are a spread of Nb–O bond distances ranging from 1.91–2.47 Å. In the fifth Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with three CaO6 octahedra and corners with three NbO6 octahedra. The corner-sharing octahedra tilt angles range from 30–51°. There are a spread of Nb–O bond distances ranging from 1.90–2.33 Å. In the sixth Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 27–40°. There are a spread of Nb–O bond distances ranging from 1.92–2.24 Å. In the seventh Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two NbO6 octahedra and corners with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 32–41°. There are a spread of Nb–O bond distances ranging from 1.98–2.24 Å. In the eighth Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 31–37°. There are a spread of Nb–O bond distances ranging from 1.93–2.22 Å. There are thirty-six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to four Ca2+ and one Nb5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the sixth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted corner-sharing OCa3Nb tetrahedra. In the seventh O2- site, O2- is bonded in a distorted see-saw-like geometry to three Ca2+ and one Nb5+ atom. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the ninth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the tenth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the eleventh O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the thirteenth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted corner-sharing OCa3Nb tetrahedra. In the fourteenth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the fifteenth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the eighteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to three Ca2+ and one Nb5+ atom. In the nineteenth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted corner-sharing OCa3Nb tetrahedra. In the twentieth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the twenty-first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the twenty-second O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the twenty-third O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the twenty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the twenty-sixth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the twenty-seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the twenty-eighth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the twenty-ninth O2- site, O2- is bonded to two Ca2+ and two Nb5+ atoms to form distorted corner-sharing OCa2Nb2 trigonal pyramids. In the thirtieth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted corner-sharing OCa3Nb trigonal pyramids. In the thirty-first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the thirty-second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the thirty-third O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the thirty-fourth O2- site, O2- is bonded in a 3-coordinate geometry to four Ca2+ and one Nb5+ atom. In the thirty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the thirty-sixth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and two Nb5+ atoms.