Materials Data on Eu2NbGaO7 by Materials Project

Abstract

Eu2NbGaO7 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are two inequivalent Eu3+ sites. In the first Eu3+ site, Eu3+ is bonded to eight O2- atoms to form distorted EuO8 hexagonal bipyramids that share edges with six EuO8 hexagonal bipyramids, edges with two equivalent GaO6 octahedra, and edges with four equivalent NbO6 octahedra. There are a spread of Eu–O bond distances ranging from 2.25–2.61 Å. In the second Eu3+ site, Eu3+ is bonded to eight O2- atoms to form distorted EuO8 hexagonal bipyramids that share edges with six EuO8 hexagonal bipyramids, edges with two equivalent NbO6 octahedra, and edges with four equivalent GaO6 octahedra. There are a spread of Eu–O bond distances ranging from 2.28–2.58 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent GaO6 octahedra, and edges with six EuO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 46–47°. There are four shorter (2.00 Å) and two longer (2.03 Å) Nb–O bond lengths. Ga3+ is bonded to six O2- atoms to form GaO6 octahedra that share corners with two equivalent GaO6 octahedra, corners with four equivalent NbO6 octahedra, and edges with six EuO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 47–50°. There are two shorter (2.01 Å) and four longer (2.03 Å) Ga–O bond lengths. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to four Eu3+ atoms to form corner-sharing OEu4 tetrahedra. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Eu3+ and two equivalent Nb5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Eu3+ and two equivalent Ga3+ atoms. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to two Eu3+, one Nb5+, and one Ga3+ atom.