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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on La2Ce2O7 by Materials Project

La2Ce2O7 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Ce4+ is bonded to six equivalent O2- atoms to form distorted corner-sharing CeO6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Ce–O bond lengths are 2.25 Å. La3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are two shorter (2.43 Å) and six longer (2.64 Å) La–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to four equivalent La3+ atoms to form OLa4 tetrahedra that share corners with sixteen OLa4 tetrahedra and edges with six equivalent OLa2Ce2 tetrahedra. In the second O2- site, O2- is bonded to two equivalent Ce4+ and two equivalent La3+ atoms to form a mixture of distorted edge and corner-sharing OLa2Ce2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La3Ce4O12 by Materials Project

Ce4La3O12 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ce+3.75+ sites. In the first Ce+3.75+ site, Ce+3.75+ is bonded to seven O2- atoms to form distorted CeO7 hexagonal pyramids that share a cornercorner with one LaO6 octahedra and edges with two equivalent CeO7 hexagonal pyramids. The corner-sharing octahedral tilt angles are 58°. There are a spread of Ce–O bond distances ranging from 2.26–2.45 Å. In the second Ce+3.75+ site, Ce+3.75+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.31–2.62 Å. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded to six O2- atoms to form LaO6 octahedra that share corners with two equivalent CeO7 hexagonal pyramids and edges with two equivalent LaO6 octahedra. There are four shorter (2.42 Å) and two longer (2.44 Å) La–O bond lengths. In the second La3+ site, La3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.34–2.68 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ce+3.75+ and one La3+ atom to form a mixture of distorted edge and corner-sharing OLaCe3 tetrahedra. In the second O2- site, O2- is bonded to four La3+ atoms to form distorted OLa4 tetrahedra that share corners with twelve OLaCe3 tetrahedra and edges with four OLa3Ce tetrahedra. In the third O2- site, O2- is bonded to three Ce+3.75+ and one La3+ atom to form OLaCe3 tetrahedra that share corners with twelve OLaCe3 tetrahedra and edges with six OCe4 tetrahedra. In the fourth O2- site, O2- is bonded to four Ce+3.75+ atoms to form a mixture of edge and corner-sharing OCe4 tetrahedra. In the fifth O2- site, O2- is bonded to one Ce+3.75+ and three La3+ atoms to form a mixture of edge and corner-sharing OLa3Ce tetrahedra. In the sixth O2- site, O2- is bonded to four Ce+3.75+ atoms to form OCe4 tetrahedra that share corners with fifteen OLaCe3 tetrahedra and edges with six OCe4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on La2Ce2O7 by Materials Project

La2Ce2O7 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. there are four inequivalent Ce4+ sites. In the first Ce4+ site, Ce4+ is bonded to six O2- atoms to form CeO6 octahedra that share corners with four CeO6 octahedra, a cornercorner with one LaO6 pentagonal pyramid, and an edgeedge with one LaO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 39–48°. There are a spread of Ce–O bond distances ranging from 2.17–2.33 Å. In the second Ce4+ site, Ce4+ is bonded to six O2- atoms to form corner-sharing CeO6 octahedra. The corner-sharing octahedra tilt angles range from 34–48°. There are a spread of Ce–O bond distances ranging from 2.16–2.41 Å. In the third Ce4+ site, Ce4+ is bonded to six O2- atoms to form CeO6 octahedra that share corners with four CeO6 octahedra, corners with two equivalent LaO6 pentagonal pyramids, and an edgeedge with one LaO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 38–51°. There are a spread of Ce–O bond distances ranging from 2.16–2.38 Å. In the fourth Ce4+ site, Ce4+ is bonded to six O2- atoms to form distorted corner-sharing CeO6 octahedra. The corner-sharing octahedra tilt angles range from 31–51°. There are a spread of Ce–O bond distances ranging from 2.17–2.50 Å. There are four inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of La–O bond distances ranging from 2.37–2.77 Å. In the second La3+ site, La3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of La–O bond distances ranging from 2.44–2.68 Å. In the third La3+ site, La3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of La–O bond distances ranging from 2.45–2.77 Å. In the fourth La3+ site, La3+ is bonded to six O2- atoms to form distorted LaO6 pentagonal pyramids that share corners with three CeO6 octahedra, corners with two equivalent LaO6 pentagonal pyramids, and edges with two CeO6 octahedra. The corner-sharing octahedra tilt angles range from 62–76°. There are a spread of La–O bond distances ranging from 2.35–2.77 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ce4+ and two La3+ atoms to form distorted OLa2Ce2 tetrahedra that share corners with five OLa3Ce tetrahedra and an edgeedge with one OLa2Ce2 tetrahedra. In the second O2- site, O2- is bonded to one Ce4+ and three La3+ atoms to form distorted OLa3Ce tetrahedra that share corners with five OLa2Ce2 tetrahedra and edges with four OLa3Ce tetrahedra. In the third O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Ce4+ and one La3+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ce4+ and one La3+ atom. In the fifth O2- site, O2- is bonded to one Ce4+ and three La3+ atoms to form distorted OLa3Ce tetrahedra that share corners with seven OLa2Ce2 tetrahedra and edges with three equivalent OLa3Ce tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ce4+ and two La3+ atoms. In the seventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ce4+ and one La3+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ce4+ and two La3+ atoms. In the ninth O2- site, O2- is bonded to two Ce4+ and two La3+ atoms to form a mixture of distorted corner and edge-sharing OLa2Ce2 tetrahedra. In the tenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Ce4+ and two La3+ atoms. In the eleventh O2- site, O2- is bonded to two Ce4+ and two La3+ atoms to form a mixture of distorted corner and edge-sharing OLa2Ce2 tetrahedra. In the twelfth O2- site, O2- is bonded to one Ce4+ and three La3+ atoms to form a mixture of distorted corner and edge-sharing OLa3Ce tetrahedra. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ce4+ and two La3+ atoms. In the fourteenth O2- site, O2- is bonded in a distorted T-shaped geometry to two Ce4+ and one La3+ atom.

36 MATERIALS SCIENCE↗