Materials Data on EuNb8O14 by Materials Project

Abstract

EuNb8O14 crystallizes in the orthorhombic Pbam space group. The structure is three-dimensional. Eu2+ is bonded to twelve O2- atoms to form EuO12 cuboctahedra that share corners with two equivalent EuO12 cuboctahedra, corners with four equivalent NbO5 square pyramids, edges with six NbO5 square pyramids, faces with four equivalent NbO6 octahedra, and faces with two equivalent NbO5 square pyramids. There are a spread of Eu–O bond distances ranging from 2.69–3.01 Å. There are three inequivalent Nb+3.25+ sites. In the first Nb+3.25+ site, Nb+3.25+ is bonded to six O2- atoms to form NbO6 octahedra that share a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, edges with two equivalent NbO5 square pyramids, and faces with two equivalent EuO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. There are a spread of Nb–O bond distances ranging from 1.98–2.09 Å. In the second Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share corners with four equivalent NbO6 octahedra, corners with six equivalent NbO5 square pyramids, an edgeedge with one EuO12 cuboctahedra, and a faceface with one EuO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–46°. There are a spread of Nb–O bond distances ranging from 2.10–2.21 Å. In the third Nb+3.25+ site, Nb+3.25+ is bonded to five O2- atoms to form NbO5 square pyramids that share a cornercorner with one EuO12 cuboctahedra, a cornercorner with one NbO6 octahedra, corners with six NbO5 square pyramids, an edgeedge with one EuO12 cuboctahedra, an edgeedge with one NbO6 octahedra, and an edgeedge with one NbO5 square pyramid. The corner-sharing octahedral tilt angles are 48°. There are a spread of Nb–O bond distances ranging from 2.06–2.19 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a linear geometry to two equivalent Eu2+ and two equivalent Nb+3.25+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to three Nb+3.25+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Eu2+ and three Nb+3.25+ atoms. In the fourth O2- site, O2- is bonded in a square co-planar geometry to four equivalent Nb+3.25+ atoms. In the fifth O2- site, O2- is bonded in a distorted T-shaped geometry to one Eu2+ and three Nb+3.25+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Eu2+ and three Nb+3.25+ atoms.