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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BaNb8O14 by Materials Project

BaNb8O14 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with two equivalent BaO12 cuboctahedra, corners with four equivalent NbO5 square pyramids, edges with six NbO5 square pyramids, faces with four equivalent NbO6 octahedra, and faces with two equivalent NbO5 square pyramids. There are a spread of Ba–O bond distances ranging from 2.83–3.01 Å. There are three inequivalent Nb+3.25+ sites. In the first Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, edges with two equivalent NbO5 square pyramids, and faces with two equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–O bond distances ranging from 1.97–2.09 Å. In the second Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with four equivalent NbO6 octahedra, corners with six equivalent NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 3–45°. There are a spread of Nb–O bond distances ranging from 2.11–2.21 Å. In the third Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one BaO12 cuboctahedra, a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, an edgeedge with one NbO6 octahedra, and an edgeedge with one NbO5 square pyramid. The corner-sharing octahedral tilt angles are 47°. There are a spread of Nb–O bond distances ranging from 2.05–2.19 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to two equivalent Ba2+ and two equivalent Nb+3.25+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.25+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ba2+ and three Nb+3.25+ atoms. In the fourth O2- site, O2- is bonded in a square co-planar geometry to four equivalent Nb+3.25+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.25+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaNb8O14 by Materials Project

BaNb8O14 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ba2+ is bonded in a 12-coordinate geometry to twelve O2- atoms. There are a spread of Ba–O bond distances ranging from 2.69–3.30 Å. There are eight inequivalent Nb+3.25+ sites. In the first Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, and edges with two NbO5 square pyramids. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–O bond distances ranging from 1.99–2.15 Å. In the second Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with three NbO6 octahedra, corners with six NbO5 square pyramids, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 5–44°. There are a spread of Nb–O bond distances ranging from 2.07–2.27 Å. In the third Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with three NbO6 octahedra and corners with six NbO5 square pyramids. The corner-sharing octahedra tilt angles range from 5–48°. There are a spread of Nb–O bond distances ranging from 2.04–2.24 Å. In the fourth Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Nb–O bond distances ranging from 1.97–2.28 Å. In the fifth Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are a spread of Nb–O bond distances ranging from 2.07–2.28 Å. In the sixth Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one NbO6 octahedra, and an edgeedge with one NbO5 square pyramid. The corner-sharing octahedral tilt angles are 44°. There are a spread of Nb–O bond distances ranging from 2.06–2.20 Å. In the seventh Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one NbO6 octahedra, and an edgeedge with one NbO5 square pyramid. The corner-sharing octahedral tilt angles are 48°. There are a spread of Nb–O bond distances ranging from 2.07–2.18 Å. In the eighth Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with four NbO5 square pyramids, an edgeedge with one NbO6 octahedra, and edges with four NbO5 square pyramids. There are a spread of Nb–O bond distances ranging from 1.90–2.25 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a square co-planar geometry to four Nb+3.25+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Ba2+ and two equivalent Nb+3.25+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ba2+ and three Nb+3.25+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+ and two Nb+3.25+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and four Nb+3.25+ atoms. In the sixth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.25+ atoms. In the seventh O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.25+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.25+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the fifteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaNb8O14 by Materials Project

BaNb8O14 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share a cornercorner with one BaO12 cuboctahedra, corners with two equivalent NbO6 octahedra, corners with six NbO5 square pyramids, edges with six NbO5 square pyramids, faces with three NbO6 octahedra, and faces with two NbO5 square pyramids. The corner-sharing octahedra tilt angles range from 29–54°. There are a spread of Ba–O bond distances ranging from 2.84–3.26 Å. There are nine inequivalent Nb+3.25+ sites. In the first Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one BaO12 cuboctahedra, a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, an edgeedge with one NbO6 octahedra, and an edgeedge with one NbO5 square pyramid. The corner-sharing octahedral tilt angles are 46°. There are a spread of Nb–O bond distances ranging from 2.07–2.18 Å. In the second Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one BaO12 cuboctahedra, a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, an edgeedge with one NbO6 octahedra, and an edgeedge with one NbO5 square pyramid. The corner-sharing octahedral tilt angles are 48°. There are a spread of Nb–O bond distances ranging from 2.07–2.19 Å. In the third Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with two equivalent NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, an edgeedge with one NbO6 octahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–46°. There are a spread of Nb–O bond distances ranging from 2.08–2.25 Å. In the fourth Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with four NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–51°. There are a spread of Nb–O bond distances ranging from 2.10–2.25 Å. In the fifth Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with two equivalent BaO12 cuboctahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, and edges with two equivalent NbO6 octahedra. There are a spread of Nb–O bond distances ranging from 2.09–2.24 Å. In the sixth Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with two equivalent BaO12 cuboctahedra, corners with two equivalent NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one BaO12 cuboctahedra, and an edgeedge with one NbO6 octahedra. The corner-sharing octahedra tilt angles range from 42–46°. There are a spread of Nb–O bond distances ranging from 2.08–2.22 Å. In the seventh Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent BaO12 cuboctahedra, corners with four NbO5 square pyramids, edges with four NbO5 square pyramids, and a faceface with one BaO12 cuboctahedra. There are a spread of Nb–O bond distances ranging from 1.91–2.15 Å. In the eighth Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, edges with two equivalent NbO5 square pyramids, and faces with two equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–O bond distances ranging from 1.99–2.09 Å. In the ninth Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, edges with two equivalent NbO5 square pyramids, and faces with two equivalent BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–O bond distances ranging from 1.99–2.08 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.25+ atoms. In the fourth O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.25+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the seventh O2- site, O2- is bonded in a distorted T-shaped geometry to one Ba2+ and three Nb+3.25+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ba2+ and three Nb+3.25+ atoms. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ba2+ and three Nb+3.25+ atoms. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.25+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to three Nb+3.25+ atoms. In the fourteenth O2- site, O2- is bonded in a square co-planar geometry to four Nb+3.25+ atoms. In the fifteenth O2- site, O2- is bonded in a linear geometry to two equivalent Ba2+ and two Nb+3.25+ atoms. In the sixteenth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.25+ atoms.

36 MATERIALS SCIENCE↗
NASA NTRS1990

Crystal chemical and quantum chemical studies of Ba(Sr)-Nb oxide compounds

The information available on the BaO(SrO)-NbO-NbO2 system with the niobium atom in the lower oxidation degree is very limited. Very few compounds have been found previously in this system. They are BaNbO3, SrxNbO3(0,7=x=1), Ba2Nb2O9, SrNb8O14; and some suggestions on the BaNb8O14 existence have been made also. At the same time Nb-based oxide compounds could be quite interesting in the search of new noncopper high T(sub c) superconductors Researchers studied Ba(Sr) NbxO2x-2 and Ba2(Sr2)-NbxO2x-1 compositions in the phase diagram of BaO(SrO)-NbO-NbO2 system. The synthesis of the materials was carried out in vacuum at the temperatures of 1000 to 1500 C. Barium carbonate and niobium pentoxide were used as initial components. X-ray analysis was carried out.

Zubkov, V. G.↗