DOE OSTI2020
SmCe4O9 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Sm3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sm–O bond distances ranging from 2.28–2.40 Å. There are four inequivalent Ce+3.75+ sites. In the first 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 2.32–2.68 Å. In the second Ce+3.75+ site, Ce+3.75+ is bonded to seven O2- atoms to form a mixture of distorted edge and corner-sharing CeO7 hexagonal pyramids. There are a spread of Ce–O bond distances ranging from 2.26–2.43 Å. In the third Ce+3.75+ site, Ce+3.75+ is bonded to seven O2- atoms to form a mixture of distorted edge and corner-sharing CeO7 hexagonal pyramids. There are a spread of Ce–O bond distances ranging from 2.27–2.43 Å. In the fourth 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 2.33–2.68 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to four Ce+3.75+ atoms to form OCe4 tetrahedra that share corners with fourteen OCe4 tetrahedra, a cornercorner with one OCe3Sm trigonal pyramid, edges with four OCe4 tetrahedra, and edges with two equivalent OCe3Sm trigonal pyramids. In the second O2- site, O2- is bonded to one Sm3+ and three Ce+3.75+ atoms to form distorted OCe3Sm trigonal pyramids that share corners with thirteen OCe4 tetrahedra, corners with three OCe3Sm trigonal pyramids, and edges with four OCe3Sm tetrahedra. In the third O2- site, O2- is bonded to one Sm3+ and three Ce+3.75+ atoms to form distorted OCe3Sm trigonal pyramids that share corners with thirteen OCe4 tetrahedra, corners with three OCe3Sm trigonal pyramids, and edges with four OCe4 tetrahedra. In the fourth O2- site, O2- is bonded to four Ce+3.75+ atoms to form OCe4 tetrahedra that share corners with fourteen OCe4 tetrahedra, a cornercorner with one OCe3Sm trigonal pyramid, edges with four OCe4 tetrahedra, and edges with two equivalent OCe3Sm trigonal pyramids. In the fifth O2- site, O2- is bonded to one Sm3+ and three Ce+3.75+ atoms to form OCe3Sm tetrahedra that share corners with nine OCe4 tetrahedra, corners with three OCe3Sm trigonal pyramids, edges with four OCe4 tetrahedra, and edges with two equivalent OCe3Sm trigonal pyramids. In the sixth O2- site, O2- is bonded to four Ce+3.75+ atoms to form OCe4 tetrahedra that share corners with ten OCe4 tetrahedra, corners with five OCe3Sm trigonal pyramids, and edges with six OCe4 tetrahedra. In the seventh O2- site, O2- is bonded to four Ce+3.75+ atoms to form OCe4 tetrahedra that share corners with ten OCe4 tetrahedra, corners with five OCe3Sm trigonal pyramids, and edges with six OCe4 tetrahedra. In the eighth O2- site, O2- is bonded to one Sm3+ and three Ce+3.75+ atoms to form OCe3Sm tetrahedra that share corners with nine OCe4 tetrahedra, corners with three OCe3Sm trigonal pyramids, edges with four OCe4 tetrahedra, and edges with two equivalent OCe3Sm trigonal pyramids. In the ninth O2- site, O2- is bonded to two equivalent Sm3+ and two Ce+3.75+ atoms to form OCe2Sm2 tetrahedra that share corners with six OCe4 tetrahedra, corners with eight OCe3Sm trigonal pyramids, and edges with four OCe3Sm tetrahedra.