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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on UNb2O7 by Materials Project

UNb2O7 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. U4+ is bonded to seven O2- atoms to form distorted edge-sharing UO7 hexagonal pyramids. There are one shorter (2.24 Å) and six longer (2.30 Å) U–O bond lengths. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Nb–O bond distances ranging from 1.84–2.45 Å. In the second Nb5+ site, Nb5+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nb–O bond distances ranging from 1.98–2.40 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a trigonal planar geometry to two equivalent U4+ and one Nb5+ atom. In the second O2- site, O2- is bonded in a linear geometry to one U4+ and one Nb5+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to three Nb5+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to three Nb5+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one U4+ and two equivalent Nb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UNb3O10 by Materials Project

UNb3O10 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. U5+ is bonded in a distorted linear geometry to six O2- atoms. There are two shorter (1.87 Å) and four longer (2.62 Å) U–O bond lengths. There are two inequivalent Nb5+ sites. In the first Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 0–38°. There are a spread of Nb–O bond distances ranging from 1.86–2.35 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 0–38°. There is four shorter (1.99 Å) and two longer (2.00 Å) Nb–O bond length. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a distorted linear geometry to one U5+ and one Nb5+ atom. The O–Nb bond length is 2.35 Å. In the third O2- site, O2- is bonded in a distorted linear geometry to one U5+ and one Nb5+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to one U5+ and two Nb5+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two Nb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UNb6O16 by Materials Project

UNb6O16 crystallizes in the monoclinic C2 space group. The structure is three-dimensional. U4+ is bonded to six O2- atoms to form distorted UO6 octahedra that share corners with four equivalent NbO6 octahedra, corners with four equivalent NbO6 pentagonal pyramids, and edges with two equivalent UO6 octahedra. The corner-sharing octahedra tilt angles range from 36–64°. There are a spread of U–O bond distances ranging from 2.28–2.41 Å. There are three inequivalent Nb+4.67+ sites. In the first Nb+4.67+ site, Nb+4.67+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with two equivalent UO6 octahedra, corners with two equivalent NbO6 octahedra, a cornercorner with one NbO6 pentagonal pyramid, an edgeedge with one NbO6 octahedra, and edges with two equivalent NbO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 36–64°. There are a spread of Nb–O bond distances ranging from 1.84–2.34 Å. In the second Nb+4.67+ site, Nb+4.67+ is bonded to six O2- atoms to form distorted NbO6 pentagonal pyramids that share corners with two equivalent UO6 octahedra, corners with four NbO6 pentagonal pyramids, and edges with two equivalent NbO6 octahedra. The corner-sharing octahedra tilt angles range from 58–67°. There are a spread of Nb–O bond distances ranging from 1.92–2.28 Å. In the third Nb+4.67+ site, Nb+4.67+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing NbO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 9°. There are a spread of Nb–O bond distances ranging from 1.95–2.16 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one U4+ and two equivalent Nb+4.67+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+4.67+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two equivalent U4+ and one Nb+4.67+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+4.67+ atoms. In the fifth O2- site, O2- is bonded in a linear geometry to two Nb+4.67+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to two Nb+4.67+ atoms. In the seventh O2- site, O2- is bonded in a linear geometry to two Nb+4.67+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three equivalent Nb+4.67+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on U2Nb6O21 by Materials Project

U2Nb6O21 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. U6+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of U–O bond distances ranging from 1.80–2.56 Å. There are four 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 24–58°. There are a spread of Nb–O bond distances ranging from 1.89–2.25 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 39–50°. There are a spread of Nb–O bond distances ranging from 1.96–2.08 Å. In the third Nb5+ site, Nb5+ is bonded to six O2- atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 24–63°. There are a spread of Nb–O bond distances ranging from 1.86–2.13 Å. In the fourth Nb5+ site, Nb5+ is bonded to six O2- atoms to form corner-sharing NbO6 octahedra. The corner-sharing octahedra tilt angles range from 35–50°. There are a spread of Nb–O bond distances ranging from 1.96–2.05 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one U6+ and two Nb5+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one U6+ and two Nb5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one U6+ and two Nb5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one U6+ and two Nb5+ atoms. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Nb5+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms. In the ninth O2- site, O2- is bonded in a single-bond geometry to one U6+ atom. In the tenth O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent U6+ atoms. In the eleventh O2- site, O2- is bonded in a distorted tetrahedral geometry to two equivalent U6+ and two equivalent Nb5+ atoms. In the twelfth O2- site, O2- is bonded in a bent 150 degrees geometry to two Nb5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on UNb4O12 by Materials Project

UNb4O12 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. U4+ is bonded to twelve O2- atoms to form UO12 cuboctahedra that share corners with four equivalent UO12 cuboctahedra and faces with eight equivalent NbO6 octahedra. There are eight shorter (2.56 Å) and four longer (2.80 Å) U–O bond lengths. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with six equivalent NbO6 octahedra and faces with two equivalent UO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–16°. There are a spread of Nb–O bond distances ranging from 1.95–2.02 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted T-shaped geometry to one U4+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a linear geometry to two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two equivalent U4+ and two equivalent Nb5+ atoms.

36 MATERIALS SCIENCE↗