DOE OSTI2020
Gd4Mo4O11 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. there are four inequivalent Gd3+ sites. In the first Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 pentagonal bipyramids that share edges with two equivalent GdO7 pentagonal bipyramids and edges with two equivalent MoO5 square pyramids. There are a spread of Gd–O bond distances ranging from 2.30–2.50 Å. In the second Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 pentagonal bipyramids that share edges with three GdO7 pentagonal bipyramids and edges with two equivalent MoO5 square pyramids. There are a spread of Gd–O bond distances ranging from 2.31–2.44 Å. In the third Gd3+ site, Gd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Gd–O bond distances ranging from 2.32–2.65 Å. In the fourth Gd3+ site, Gd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Gd–O bond distances ranging from 2.28–2.73 Å. There are three inequivalent Mo+2.50+ sites. In the first Mo+2.50+ site, Mo+2.50+ is bonded to five O2- atoms to form MoO5 square pyramids that share edges with two GdO7 pentagonal bipyramids and edges with two equivalent MoO5 square pyramids. There are a spread of Mo–O bond distances ranging from 2.10–2.13 Å. In the second Mo+2.50+ site, Mo+2.50+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are two shorter (2.11 Å) and two longer (2.12 Å) Mo–O bond lengths. In the third Mo+2.50+ site, Mo+2.50+ is bonded in a rectangular see-saw-like geometry to four O2- atoms. There are a spread of Mo–O bond distances ranging from 2.08–2.17 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to three Gd3+ and one Mo+2.50+ atom to form distorted OGd3Mo tetrahedra that share corners with seven OGd3Mo tetrahedra, corners with two equivalent OGd3Mo2 trigonal bipyramids, corners with three OGdMo3 trigonal pyramids, edges with two OGd3Mo tetrahedra, and an edgeedge with one OGd3Mo2 trigonal bipyramid. In the second O2- site, O2- is bonded to one Gd3+ and three Mo+2.50+ atoms to form OGdMo3 trigonal pyramids that share corners with six OGd3Mo tetrahedra, a cornercorner with one OGdMo3 trigonal pyramid, edges with two equivalent OGd3Mo2 trigonal bipyramids, and an edgeedge with one OGdMo3 trigonal pyramid. In the third O2- site, O2- is bonded to one Gd3+ and three Mo+2.50+ atoms to form OGdMo3 trigonal pyramids that share corners with six OGd3Mo tetrahedra, a cornercorner with one OGdMo3 trigonal pyramid, edges with two equivalent OGd3Mo2 trigonal bipyramids, and an edgeedge with one OGdMo3 trigonal pyramid. In the fourth O2- site, O2- is bonded to three Gd3+ and two Mo+2.50+ atoms to form distorted OGd3Mo2 trigonal bipyramids that share corners with eight OGd3Mo tetrahedra, edges with two OGd3Mo tetrahedra, an edgeedge with one OGd3Mo2 trigonal bipyramid, edges with two OGdMo3 trigonal pyramids, and a faceface with one OGd3Mo2 trigonal bipyramid. In the fifth O2- site, O2- is bonded to four Gd3+ atoms to form distorted OGd4 tetrahedra that share corners with eight OGd3Mo tetrahedra, corners with four equivalent OGd3Mo2 trigonal bipyramids, corners with two equivalent OGdMo3 trigonal pyramids, and edges with four OGd4 tetrahedra. In the sixth O2- site, O2- is bonded in a rectangular see-saw-like geometry to one Gd3+ and three Mo+2.50+ atoms. In the seventh O2- site, O2- is bonded to four Gd3+ atoms to form OGd4 tetrahedra that share corners with six OGd3Mo tetrahedra, corners with four equivalent OGd3Mo2 trigonal bipyramids, corners with two OGdMo3 trigonal pyramids, edges with four OGd4 tetrahedra, and an edgeedge with one OGd3Mo2 trigonal bipyramid. In the eighth O2- site, O2- is bonded in a distorted see-saw-like geometry to one Gd3+ and three Mo+2.50+ atoms.