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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on NaCeTiNbO6F by Materials Project

NaCeTiNbO6F crystallizes in the tetragonal P4_122 space group. The structure is three-dimensional. Na1+ is bonded to six O2- and two equivalent F1- atoms to form distorted NaO6F2 hexagonal bipyramids that share edges with two equivalent NaO6F2 hexagonal bipyramids, edges with four equivalent CeO6F2 hexagonal bipyramids, edges with two equivalent TiO6 octahedra, and edges with four equivalent NbO6 octahedra. There are a spread of Na–O bond distances ranging from 2.56–2.79 Å. Both Na–F bond lengths are 2.19 Å. Ce3+ is bonded to six O2- and two equivalent F1- atoms to form distorted CeO6F2 hexagonal bipyramids that share edges with two equivalent CeO6F2 hexagonal bipyramids, edges with four equivalent NaO6F2 hexagonal bipyramids, edges with two equivalent NbO6 octahedra, and edges with four equivalent TiO6 octahedra. There are a spread of Ce–O bond distances ranging from 2.46–2.67 Å. Both Ce–F bond lengths are 2.34 Å. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with four equivalent NbO6 octahedra, edges with two equivalent NaO6F2 hexagonal bipyramids, and edges with four equivalent CeO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 45–48°. There are a spread of Ti–O bond distances ranging from 1.97–2.00 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent TiO6 octahedra, edges with two equivalent CeO6F2 hexagonal bipyramids, and edges with four equivalent NaO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 40–45°. There are a spread of Nb–O bond distances ranging from 2.00–2.02 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ce3+, one Ti4+, and one Nb5+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ce3+ and two equivalent Ti4+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ce3+, one Ti4+, and one Nb5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Nb5+ atoms. F1- is bonded to two equivalent Na1+ and two equivalent Ce3+ atoms to form corner-sharing FNa2Ce2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaCeTiNbO6F by Materials Project

NaCeTiNbO6F crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Na1+ is bonded to six O2- and two equivalent F1- atoms to form distorted NaO6F2 hexagonal bipyramids that share edges with two equivalent NaO6F2 hexagonal bipyramids, edges with four equivalent CeO6F2 hexagonal bipyramids, edges with two equivalent TiO6 octahedra, and edges with four equivalent NbO6 octahedra. There are two shorter (2.63 Å) and four longer (2.72 Å) Na–O bond lengths. Both Na–F bond lengths are 2.20 Å. Ce3+ is bonded to six O2- and two equivalent F1- atoms to form distorted CeO6F2 hexagonal bipyramids that share edges with two equivalent CeO6F2 hexagonal bipyramids, edges with four equivalent NaO6F2 hexagonal bipyramids, edges with two equivalent NbO6 octahedra, and edges with four equivalent TiO6 octahedra. There are four shorter (2.52 Å) and two longer (2.61 Å) Ce–O bond lengths. Both Ce–F bond lengths are 2.33 Å. Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent TiO6 octahedra, corners with four equivalent NbO6 octahedra, edges with two equivalent NaO6F2 hexagonal bipyramids, and edges with four equivalent CeO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 45–48°. All Ti–O bond lengths are 1.99 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent TiO6 octahedra, edges with two equivalent CeO6F2 hexagonal bipyramids, and edges with four equivalent NaO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 40–45°. There are four shorter (2.01 Å) and two longer (2.02 Å) Nb–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ce3+ and two equivalent Ti4+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+ and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ce3+, one Ti4+, and one Nb5+ atom. F1- is bonded to two equivalent Na1+ and two equivalent Ce3+ atoms to form corner-sharing FNa2Ce2 tetrahedra.

36 MATERIALS SCIENCE↗