DOI: 10.17188/1268465
title: Materials Data on Nd4Ga2O9 by Materials Project

description: Nd4Ga2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded to seven O2- atoms to form distorted NdO7 hexagonal pyramids that share a cornercorner with one GaO4 tetrahedra, corners with two equivalent GaO4 trigonal pyramids, edges with two equivalent NdO6 octahedra, an edgeedge with one GaO4 tetrahedra, and an edgeedge with one GaO4 trigonal pyramid. There are a spread of Nd–O bond distances ranging from 2.35–2.60 Å. In the second Nd3+ site, Nd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nd–O bond distances ranging from 2.35–2.81 Å. In the third Nd3+ site, Nd3+ is bonded to six O2- atoms to form NdO6 octahedra that share corners with three equivalent GaO4 tetrahedra, corners with two equivalent GaO4 trigonal pyramids, and edges with two equivalent NdO7 hexagonal pyramids. There are a spread of Nd–O bond distances ranging from 2.31–2.47 Å. In the fourth Nd3+ site, Nd3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Nd–O bond distances ranging from 2.39–2.80 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 a cornercorner with one NdO7 hexagonal pyramid, corners with three equivalent NdO6 octahedra, a cornercorner with one GaO4 trigonal pyramid, and an edgeedge with one NdO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 51–63°. There are a spread of Ga–O bond distances ranging from 1.84–1.89 Å. In the second Ga3+ site, Ga3+ is bonded to four O2- atoms to form GaO4 trigonal pyramids that share corners with two equivalent NdO7 hexagonal pyramids, corners with two equivalent NdO6 octahedra, a cornercorner with one GaO4 tetrahedra, and an edgeedge with one NdO7 hexagonal pyramid. The corner-sharing octahedra tilt angles range from 41–54°. There are a spread of Ga–O bond distances ranging from 1.83–1.89 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Nd3+ and one Ga3+ atom. In the second O2- site, O2- is bonded to two Nd3+ and two Ga3+ atoms to form distorted ONd2Ga2 tetrahedra that share corners with three ONd4 tetrahedra, corners with two equivalent ONd3Ga trigonal pyramids, and edges with two ONd4 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Nd3+ and one Ga3+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Nd3+ and one Ga3+ atom. In the fifth O2- site, O2- is bonded to four Nd3+ atoms to form ONd4 tetrahedra that share corners with five ONd2Ga2 tetrahedra, a cornercorner with one ONd3Ga trigonal pyramid, edges with two ONd4 tetrahedra, and an edgeedge with one ONd3Ga trigonal pyramid. In the sixth O2- site, O2- is bonded to four Nd3+ atoms to form ONd4 tetrahedra that share corners with six ONd2Ga2 tetrahedra, edges with three ONd2Ga2 tetrahedra, and an edgeedge with one ONd3Ga trigonal pyramid. In the seventh O2- site, O2- is bonded to three Nd3+ and one Ga3+ atom to form distorted ONd3Ga trigonal pyramids that share corners with three ONd2Ga2 tetrahedra and edges with three ONd4 tetrahedra. In the eighth O2- site, O2- is bonded to three Nd3+ and one Ga3+ atom to form distorted ONd3Ga tetrahedra that share corners with six ONd2Ga2 tetrahedra, an edgeedge with one ONd2Ga2 tetrahedra, and an edgeedge with one ONd3Ga trigonal pyramid. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Nd3+ and one Ga3+ atom.