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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ba3CaTa2O9 by Materials Project

Ba3CaTa2O9 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 BaO12 cuboctahedra, faces with three equivalent CaO6 octahedra, and faces with five equivalent TaO6 octahedra. There are nine shorter (2.99 Å) and three longer (3.07 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 equivalent BaO12 cuboctahedra, faces with two equivalent CaO6 octahedra, and faces with six equivalent TaO6 octahedra. There are six shorter (2.95 Å) and six longer (2.99 Å) Ba–O bond lengths. Ca2+ is bonded to six equivalent O2- atoms to form CaO6 octahedra that share corners with six equivalent TaO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 3°. All Ca–O bond lengths are 2.29 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three equivalent CaO6 octahedra, corners with three equivalent TaO6 octahedra, and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There are three shorter (1.94 Å) and three longer (2.12 Å) Ta–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 Ta5+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to four Ba2+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba5Ca2Ta3O15 by Materials Project

Ba5Ca2Ta3O15 is (Cubic) Perovskite-derived structured and crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are two inequivalent Ba sites. In the first Ba site, Ba is bonded to twelve O 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 TaO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.93–3.12 Å. In the second Ba site, Ba is bonded to twelve O atoms to form BaO12 cuboctahedra that share corners with twelve equivalent BaO12 cuboctahedra, faces with six BaO12 cuboctahedra, faces with four equivalent CaO6 octahedra, and faces with four equivalent TaO6 octahedra. There are a spread of Ba–O bond distances ranging from 3.00–3.11 Å. Ca is bonded to six O atoms to form CaO6 octahedra that share corners with six TaO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–7°. There are a spread of Ca–O bond distances ranging from 2.27–2.33 Å. There are three inequivalent Ta sites. In the first Ta site, Ta is bonded to six O atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.01 Å) and two longer (2.09 Å) Ta–O bond lengths. In the second Ta site, Ta is bonded to six O atoms to form TaO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five equivalent CaO6 octahedra, and faces with eight BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–7°. There are a spread of Ta–O bond distances ranging from 1.92–2.31 Å. In the third Ta site, Ta is bonded to six O atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent CaO6 octahedra, and faces with eight equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (1.97 Å) and two longer (2.15 Å) Ta–O bond lengths. There are seven inequivalent O sites. In the first O site, O is bonded in a distorted linear geometry to four Ba, one Ca, and one Ta atom. In the second O site, O is bonded in a distorted linear geometry to four Ba, one Ca, and one Ta atom. In the third O site, O is bonded to four equivalent Ba and two Ta atoms to form a mixture of distorted face and corner-sharing OBa4Ta2 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O site, O is bonded in a distorted linear geometry to four equivalent Ba, one Ca, and one Ta atom. In the fifth O site, O is bonded in a distorted linear geometry to four equivalent Ba, one Ca, and one Ta atom. In the sixth O site, O is bonded in a distorted linear geometry to four Ba, one Ca, and one Ta atom. In the seventh O site, O is bonded in a distorted linear geometry to four equivalent Ba and two Ta atoms.

36 MATERIALS SCIENCE↗