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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ba3CaNb2O9 by Materials Project

Ba3CaNb2O9 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, faces with two equivalent CaO6 octahedra, and faces with six equivalent NbO6 octahedra. There are six shorter (2.95 Å) and six longer (3.00 Å) Ba–O bond lengths. In the second Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, faces with three equivalent CaO6 octahedra, and faces with five equivalent NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.98–3.11 Å. Ca2+ is bonded to six equivalent O2- atoms to form CaO6 octahedra that share corners with six equivalent NbO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 4°. All Ca–O bond lengths are 2.29 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with three equivalent CaO6 octahedra, corners with three equivalent NbO6 octahedra, and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are three shorter (1.94 Å) and three longer (2.14 Å) Nb–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four Ba2+, one Ca2+, and one Nb5+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Nb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba8Ca3Nb5O24 by Materials Project

Ba8Ca3Nb5O24 is (Cubic) Perovskite-derived structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Ba is bonded to twelve O atoms to form BaO12 cuboctahedra that share corners with twelve equivalent BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, faces with three CaO6 octahedra, and faces with five NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.90–3.16 Å. There are three inequivalent Ca sites. In the first Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with six NbO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are four shorter (2.28 Å) and two longer (2.32 Å) Ca–O bond lengths. In the second Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with six NbO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.28 Å) and two longer (2.31 Å) Ca–O bond lengths. In the third Ca site, Ca is bonded to six O atoms to form CaO6 octahedra that share corners with six NbO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.28 Å) and two longer (2.31 Å) Ca–O bond lengths. There are three inequivalent Nb sites. In the first Nb site, Nb is bonded to six O atoms to form distorted NbO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with five CaO6 octahedra, and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are a spread of Nb–O bond distances ranging from 1.91–2.42 Å. In the second Nb site, Nb is bonded to six O atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four CaO6 octahedra, and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–O bond distances ranging from 1.97–2.17 Å. In the third Nb site, Nb is bonded to six O atoms to form NbO6 octahedra that share corners with six NbO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (1.99 Å) and four longer (2.08 Å) Nb–O bond lengths. There are six inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to four equivalent Ba, one Ca, and one Nb atom. In the second O site, O is bonded in a distorted linear geometry to four equivalent Ba, one Ca, and one Nb atom. In the third O site, O is bonded in a distorted linear geometry to four equivalent Ba and two Nb atoms. In the fourth O site, O is bonded in a distorted linear geometry to four equivalent Ba, one Ca, and one Nb atom. In the fifth O site, O is bonded in a distorted linear geometry to four equivalent Ba, one Ca, and one Nb atom. In the sixth O site, O is bonded to four equivalent Ba and two Nb atoms to form distorted corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗