DOE OSTI2020
Ce2Y2O7 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are eight inequivalent Ce4+ sites. In the first Ce4+ site, Ce4+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ce–O bond distances ranging from 2.24–2.45 Å. In the second Ce4+ site, Ce4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.27–2.53 Å. In the third Ce4+ site, Ce4+ is bonded to seven O2- atoms to form distorted CeO7 pentagonal bipyramids that share a cornercorner with one YO7 hexagonal pyramid, corners with two YO6 octahedra, edges with two YO7 hexagonal pyramids, an edgeedge with one YO6 octahedra, and an edgeedge with one YO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 53–57°. There are a spread of Ce–O bond distances ranging from 2.25–2.46 Å. In the fourth Ce4+ site, Ce4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.25–2.70 Å. In the fifth Ce4+ site, Ce4+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ce–O bond distances ranging from 2.29–2.41 Å. In the sixth Ce4+ site, Ce4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.29–2.45 Å. In the seventh Ce4+ site, Ce4+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are a spread of Ce–O bond distances ranging from 2.25–2.57 Å. In the eighth Ce4+ site, Ce4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ce–O bond distances ranging from 2.20–2.35 Å. There are eight inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 pentagonal bipyramids that share a cornercorner with one YO7 hexagonal pyramid, a cornercorner with one YO6 octahedra, edges with two YO7 hexagonal pyramids, an edgeedge with one YO6 octahedra, and an edgeedge with one CeO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 51°. There are a spread of Y–O bond distances ranging from 2.30–2.53 Å. In the second Y3+ site, Y3+ is bonded to six O2- atoms to form distorted YO6 octahedra that share a cornercorner with one YO7 hexagonal pyramid, a cornercorner with one YO6 octahedra, an edgeedge with one YO6 octahedra, an edgeedge with one CeO7 pentagonal bipyramid, and an edgeedge with one YO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 61°. There are a spread of Y–O bond distances ranging from 2.25–2.34 Å. In the third Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 hexagonal pyramids that share corners with two YO6 octahedra, a cornercorner with one CeO7 pentagonal bipyramid, an edgeedge with one YO7 hexagonal pyramid, and an edgeedge with one YO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 55–58°. There are a spread of Y–O bond distances ranging from 2.26–2.41 Å. In the fourth Y3+ site, Y3+ is bonded to six O2- atoms to form distorted YO6 octahedra that share corners with two YO7 hexagonal pyramids, a cornercorner with one YO6 octahedra, a cornercorner with one CeO7 pentagonal bipyramid, a cornercorner with one YO7 pentagonal bipyramid, and an edgeedge with one YO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of Y–O bond distances ranging from 2.24–2.34 Å. In the fifth Y3+ site, Y3+ is bonded to six O2- atoms to form distorted YO6 octahedra that share a cornercorner with one YO7 hexagonal pyramid, corners with two YO6 octahedra, a cornercorner with one CeO7 pentagonal bipyramid, and edges with two YO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 56–61°. There are a spread of Y–O bond distances ranging from 2.24–2.35 Å. In the sixth Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 hexagonal pyramids that share a cornercorner with one YO6 octahedra, edges with two YO7 hexagonal pyramids, an edgeedge with one YO6 octahedra, an edgeedge with one CeO7 pentagonal bipyramid, and an edgeedge with one YO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 53°. There are a spread of Y–O bond distances ranging from 2.26–2.43 Å. In the seventh Y3+ site, Y3+ is bonded to seven O2- atoms to form distorted YO7 hexagonal pyramids that share a cornercorner with one YO6 octahedra, a cornercorner with one YO7 pentagonal bipyramid, an edgeedge with one YO7 hexagonal pyramid, an edgeedge with one YO6 octahedra, and an edgeedge with one CeO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 57°. There are a spread of Y–O bond distances ranging from 2.29–2.49 Å. In the eighth Y3+ site, Y3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Y–O bond distances ranging from 2.28–2.48 Å. There are twenty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing OCe2Y2 tetrahedra. In the second O2- site, O2- is bonded to one Ce4+ and three Y3+ atoms to form a mixture of distorted edge and corner-sharing OCeY3 tetrahedra. In the third O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of edge and corner-sharing OCe2Y2 tetrahedra. In the fourth O2- site, O2- is bonded to one Ce4+ and three Y3+ atoms to form OCeY3 tetrahedra that share corners with fourteen OCe2Y2 tetrahedra and edges with four OCeY3 tetrahedra. In the fifth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form OCe2Y2 tetrahedra that share corners with fourteen OCe2Y2 tetrahedra and edges with five OCeY3 tetrahedra. In the sixth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of edge and corner-sharing OCe2Y2 tetrahedra. In the seventh O2- site, O2- is bonded to one Ce4+ and three Y3+ atoms to form a mixture of distorted edge and corner-sharing OCeY3 tetrahedra. In the eighth O2- site, O2- is bonded to one Ce4+ and three Y3+ atoms to form a mixture of distorted edge and corner-sharing OCeY3 tetrahedra. In the ninth O2- site, O2- is bonded to one Ce4+ and three Y3+ atoms to form a mixture of distorted edge and corner-sharing OCeY3 tetrahedra. In the tenth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form OCe2Y2 tetrahedra that share corners with twelve OCe2Y2 tetrahedra and edges with six OCe3Y tetrahedra. In the eleventh O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form a mixture of edge and corner-sharing OCe3Y tetrahedra. In the twelfth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of edge and corner-sharing OCe2Y2 tetrahedra. In the thirteenth O2- site, O2- is bonded to one Ce4+ and three Y3+ atoms to form a mixture of edge and corner-sharing OCeY3 tetrahedra. In the fourteenth O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form a mixture of edge and corner-sharing OCe3Y tetrahedra. In the fifteenth O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form a mixture of edge and corner-sharing OCe3Y tetrahedra. In the sixteenth O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form OCe3Y tetrahedra that share corners with fourteen OCe2Y2 tetrahedra and edges with five OCe3Y tetrahedra. In the seventeenth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of distorted edge and corner-sharing OCe2Y2 tetrahedra. In the eighteenth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of edge and corner-sharing OCe2Y2 tetrahedra. In the nineteenth O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form a mixture of edge and corner-sharing OCe3Y tetrahedra. In the twentieth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of edge and corner-sharing OCe2Y2 tetrahedra. In the twenty-first O2- site, O2- is bonded to four Ce4+ atoms to form OCe4 tetrahedra that share corners with fourteen OCe2Y2 tetrahedra and edges with five OCe3Y tetrahedra. In the twenty-second O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form OCe2Y2 tetrahedra that share corners with twelve OCe2Y2 tetrahedra and edges with six OCe3Y tetrahedra. In the twenty-third O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form a mixture of edge and corner-sharing OCe3Y tetrahedra. In the twenty-fourth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form a mixture of edge and corner-sharing OCe2Y2 tetrahedra. In the twenty-fifth O2- site, O2- is bonded to three Ce4+ and one Y3+ atom to form a mixture of edge and corner-sharing OCe3Y tetrahedra. In the twenty-sixth O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form OCe2Y2 tetrahedra that share corners with thirteen OCe2Y2 tetrahedra and edges with five OCe3Y tetrahedra. In the twenty-seventh O2- site, O2- is bonded to two Ce4+ and two Y3+ atoms to form distorted OCe2Y2 tetrahedra that share corners with twelve OCe2Y2 tetrahedra and edges with five OCe3Y tetrahedra. In the twenty-eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Ce4+ and two Y3+ atoms.