DOI: 10.17188/1305639
title: Materials Data on Ba4Ce2O7 by Materials Project

description: Ba4Ce2O7 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are six inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.70–3.25 Å. In the second Ba2+ site, Ba2+ is bonded to six O2- atoms to form distorted BaO6 octahedra that share corners with five CeO4 trigonal pyramids, edges with two equivalent BaO6 octahedra, and an edgeedge with one CeO4 trigonal pyramid. There are a spread of Ba–O bond distances ranging from 2.64–3.04 Å. In the third Ba2+ site, Ba2+ is bonded in a 3-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.54–3.47 Å. In the fourth Ba2+ site, Ba2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ba–O bond distances ranging from 2.71–3.35 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ba–O bond distances ranging from 2.56–3.02 Å. In the sixth Ba2+ site, Ba2+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Ba–O bond distances ranging from 2.71–3.37 Å. There are three inequivalent Ce3+ sites. In the first Ce3+ site, Ce3+ is bonded to four O2- atoms to form CeO4 trigonal pyramids that share corners with four equivalent BaO6 octahedra and a cornercorner with one CeO4 trigonal pyramid. The corner-sharing octahedra tilt angles range from 28–90°. There are a spread of Ce–O bond distances ranging from 2.13–2.35 Å. In the second Ce3+ site, Ce3+ is bonded to four O2- atoms to form CeO4 trigonal pyramids that share a cornercorner with one BaO6 octahedra, a cornercorner with one CeO5 trigonal bipyramid, a cornercorner with one CeO4 trigonal pyramid, and an edgeedge with one BaO6 octahedra. The corner-sharing octahedral tilt angles are 60°. There are a spread of Ce–O bond distances ranging from 2.15–2.34 Å. In the third Ce3+ site, Ce3+ is bonded to five O2- atoms to form CeO5 trigonal bipyramids that share a cornercorner with one CeO5 trigonal bipyramid and a cornercorner with one CeO4 trigonal pyramid. There are a spread of Ce–O bond distances ranging from 2.18–2.51 Å. There are eleven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four Ba2+ and two equivalent Ce3+ atoms. In the second O2- site, O2- is bonded to three Ba2+ and one Ce3+ atom to form a mixture of distorted corner and edge-sharing OBa3Ce tetrahedra. In the third O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+ and one Ce3+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to four Ba2+ and one Ce3+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to four Ba2+ and two Ce3+ atoms. In the sixth O2- site, O2- is bonded to three Ba2+ and one Ce3+ atom to form distorted OBa3Ce trigonal pyramids that share corners with two equivalent OBa4Ce2 octahedra, corners with two equivalent OBa3Ce tetrahedra, corners with two equivalent OBa3Ce trigonal pyramids, and an edgeedge with one OBa3Ce tetrahedra. The corner-sharing octahedra tilt angles range from 40–76°. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to four Ba2+ and one Ce3+ atom. In the eighth O2- site, O2- is bonded to four Ba2+ and two Ce3+ atoms to form a mixture of distorted corner and edge-sharing OBa4Ce2 octahedra. In the ninth O2- site, O2- is bonded to three Ba2+ and one Ce3+ atom to form distorted OBa3Ce tetrahedra that share corners with two equivalent OBa3Ce tetrahedra and edges with two equivalent OBa4Ce2 octahedra. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to three Ba2+ and one Ce3+ atom. In the eleventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Ba2+ and one Ce3+ atom.