DOI: 10.17188/1663085
title: Materials Data on Gd4Ga2O9 by Materials Project

description: Gd4Ga2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Gd3+ sites. In the first 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 2.30–2.69 Å. In the second Gd3+ site, Gd3+ is bonded to six O2- atoms to form GdO6 octahedra that share corners with three equivalent GaO4 tetrahedra, corners with two equivalent GaO4 trigonal pyramids, and edges with two equivalent GdO7 pentagonal bipyramids. There are a spread of Gd–O bond distances ranging from 2.24–2.42 Å. In the third Gd3+ site, Gd3+ is bonded to seven O2- atoms to form distorted GdO7 pentagonal bipyramids that share a cornercorner with one GaO4 tetrahedra, corners with two equivalent GaO4 trigonal pyramids, edges with two equivalent GdO6 octahedra, an edgeedge with one GaO4 tetrahedra, and an edgeedge with one GaO4 trigonal pyramid. There are a spread of Gd–O bond distances ranging from 2.28–2.53 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 2.30–2.74 Å. There are two inequivalent Ga3+ sites. In the first Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 tetrahedra that share corners with three equivalent GdO6 octahedra, a cornercorner with one GdO7 pentagonal bipyramid, a cornercorner with one GaO4 trigonal pyramid, and an edgeedge with one GdO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 54–65°. There are a spread of Ga–O bond distances ranging from 1.83–1.89 Å. In the second Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 trigonal pyramids that share corners with two equivalent GdO6 octahedra, corners with two equivalent GdO7 pentagonal bipyramids, a cornercorner with one GaO4 tetrahedra, and an edgeedge with one GdO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 44–65°. There is three shorter (1.85 Å) and one longer (1.89 Å) Ga–O bond length. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Gd3+ and one Ga3+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Gd3+ and one Ga3+ atom. In the third O2- site, O2- is bonded to three Gd3+ and one Ga3+ atom to form distorted OGd3Ga trigonal pyramids that share corners with five OGd3Ga tetrahedra, corners with three equivalent OGd3Ga trigonal pyramids, and edges with two OGd4 tetrahedra. In the fourth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Gd3+ and one Ga3+ atom. In the fifth O2- site, O2- is bonded to three Gd3+ and one Ga3+ atom to form distorted OGd3Ga tetrahedra that share corners with six OGd4 tetrahedra, corners with two equivalent OGd3Ga trigonal pyramids, an edgeedge with one OGd2Ga2 tetrahedra, and an edgeedge with one OGd3Ga trigonal pyramid. In the sixth O2- site, O2- is bonded to four Gd3+ atoms to form OGd4 tetrahedra that share corners with six OGd3Ga tetrahedra, corners with four equivalent OGd3Ga trigonal pyramids, edges with three OGd4 tetrahedra, and an edgeedge with one OGd3Ga trigonal pyramid. In the seventh O2- site, O2- is bonded to two Gd3+ and two Ga3+ atoms to form a mixture of distorted corner and edge-sharing OGd2Ga2 tetrahedra. In the eighth O2- site, O2- is bonded to four Gd3+ atoms to form OGd4 tetrahedra that share corners with five OGd3Ga tetrahedra, corners with two OGd3Ga trigonal pyramids, edges with two OGd4 tetrahedra, and edges with two OGd3Ga trigonal pyramids. In the ninth O2- site, O2- is bonded to three Gd3+ and one Ga3+ atom to form distorted OGd3Ga trigonal pyramids that share corners with six OGd4 tetrahedra, corners with three equivalent OGd3Ga trigonal pyramids, and edges with three OGd2Ga2 tetrahedra.