Materials Data on BaNb2Fe2O9 by Materials Project
BaNb2Fe2O9 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with four equivalent BaO12 cuboctahedra, faces with four equivalent BaO12 cuboctahedra, and faces with eight equivalent NbO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.78–2.87 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with five equivalent NbO6 octahedra and faces with four equivalent BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 4–12°. There are a spread of Nb–O bond distances ranging from 1.92–2.22 Å. Fe3+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Fe–O bond distances ranging from 1.81–2.10 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded to four equivalent Ba2+ and two equivalent Nb5+ atoms to form a mixture of distorted edge and corner-sharing OBa4Nb2 octahedra. The corner-sharing octahedra tilt angles range from 0–1°. In the third O2- site, O2- is bonded in a linear geometry to one Nb5+ and one Fe3+ atom. In the fourth O2- site, O2- is bonded to four equivalent Fe3+ atoms to form a mixture of distorted edge and corner-sharing OFe4 trigonal pyramids. In the fifth O2- site, O2- is bonded in a distorted linear geometry to two equivalent Ba2+ and two equivalent Nb5+ atoms.