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Materials Data on Ca4Nb2O9 by Materials Project

Ca4Nb2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are five 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 37–43°. There are four shorter (2.30 Å) and two longer (2.32 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.32–3.04 Å. In the third 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 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 37–41°. There are a spread of Ca–O bond distances ranging from 2.28–2.33 Å. In the fifth 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 2.28–2.95 Å. There are two 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 29–41°. There are a spread of Nb–O bond distances ranging from 1.94–2.21 Å. In the second 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 28–43°. There are a spread of Nb–O bond distances ranging from 1.92–2.21 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ca2+ and two Nb5+ atoms to form distorted corner-sharing OCa2Nb2 tetrahedra. In the second O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. 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 5-coordinate geometry to three Ca2+ and two equivalent Nb5+ atoms. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two equivalent Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the eighth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted corner-sharing OCa3Nb tetrahedra. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Ca4Nb2O9 by Materials Project

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.

36 MATERIALS SCIENCE↗

Materials Data on Ca4Nb2O9 by Materials Project

Ca4Nb2O9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are nine 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 31–44°. There are a spread of Ca–O bond distances ranging from 2.28–2.35 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 2.32–2.78 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 2.29–2.60 Å. In the fourth 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 2.30–2.83 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 5-coordinate geometry to six O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.87 Å. In the sixth 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 41–43°. There are a spread of Ca–O bond distances ranging from 2.30–2.36 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 34–47°. There are a spread of Ca–O bond distances ranging from 2.28–2.33 Å. In the eighth 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 2.28–2.84 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 2.29–2.86 Å. There are five inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 28–42°. There are a spread of Nb–O bond distances ranging from 1.91–2.28 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 31–47°. 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 distorted NbO6 octahedra that share corners with three CaO6 octahedra and corners with three equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 28–41°. There are a spread of Nb–O bond distances ranging from 1.90–2.36 Å. In the fourth Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 31–44°. There are a spread of Nb–O bond distances ranging from 1.99–2.13 Å. In the fifth Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four CaO6 octahedra. The corner-sharing octahedra tilt angles range from 28–38°. There are a spread of Nb–O bond distances ranging from 1.98–2.11 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. 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 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the fourth O2- site, O2- is bonded to two Ca2+ and two Nb5+ atoms to form distorted OCa2Nb2 trigonal pyramids that share a cornercorner with one OCa3Nb tetrahedra, corners with two OCa2Nb2 trigonal pyramids, and an edgeedge with one OCa3Nb trigonal pyramid. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. 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 to three Ca2+ and one Nb5+ atom to form distorted OCa3Nb trigonal pyramids that share a cornercorner with one OCa3Nb tetrahedra, corners with three OCa2Nb2 trigonal pyramids, and an edgeedge with one OCa2Nb2 trigonal pyramid. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three 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 in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the fourteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Ca2+ and two Nb5+ atoms. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Nb5+ atom. In the sixteenth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the seventeenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the eighteenth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted OCa3Nb tetrahedra that share a cornercorner with one OCa3Nb tetrahedra and corners with two OCa2Nb2 trigonal pyramids.

36 MATERIALS SCIENCE↗

Materials Data on Ca4Nb2O9 by Materials Project

Ca4Nb2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four 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 30–47°. There are a spread of Ca–O bond distances ranging from 2.27–2.34 Å. In the second 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 2.30–2.97 Å. In the third 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 2.27–2.86 Å. In the fourth 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 2.33–2.89 Å. There are three inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra and corners with four equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 30–47°. There are a spread of Nb–O bond distances ranging from 1.92–2.31 Å. In the second Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 33–35°. There are four shorter (2.03 Å) and two longer (2.07 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 two equivalent NbO6 octahedra and corners with four equivalent CaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–37°. There are a spread of Nb–O bond distances ranging from 1.98–2.13 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted corner-sharing OCa3Nb tetrahedra. In the second O2- site, O2- is bonded in a 1-coordinate geometry to four Ca2+ and one Nb5+ atom. In the third O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the fourth O2- site, O2- is bonded to three Ca2+ and one Nb5+ atom to form distorted OCa3Nb trigonal pyramids that share corners with two equivalent OCa3Nb tetrahedra and corners with two equivalent OCa2Nb2 trigonal pyramids. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two Nb5+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Nb5+ atom. In the ninth O2- site, O2- is bonded to two Ca2+ and two Nb5+ atoms to form distorted corner-sharing OCa2Nb2 trigonal pyramids.

36 MATERIALS SCIENCE↗