Materials Data on BaTbFe4O7 by Materials Project

BaTbFe4O7 crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are three shorter (2.76 Å) and six longer (3.20 Å) Ba–O bond lengths. Tb3+ is bonded to six O2- atoms to form TbO6 octahedra that share corners with three equivalent FeO4 tetrahedra and corners with nine equivalent FeO4 trigonal pyramids. There are three shorter (2.23 Å) and three longer (2.33 Å) Tb–O bond lengths. There are two inequivalent Fe+2.25+ sites. In the first Fe+2.25+ site, Fe+2.25+ is bonded to four O2- atoms to form FeO4 trigonal pyramids that share corners with three equivalent TbO6 octahedra, corners with two equivalent FeO4 tetrahedra, and corners with four equivalent FeO4 trigonal pyramids. The corner-sharing octahedra tilt angles range from 47–67°. There are a spread of Fe–O bond distances ranging from 1.96–2.21 Å. In the second Fe+2.25+ site, Fe+2.25+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with three equivalent TbO6 octahedra and corners with six equivalent FeO4 trigonal pyramids. The corner-sharing octahedral tilt angles are 58°. There is three shorter (1.91 Å) and one longer (1.92 Å) Fe–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a tetrahedral geometry to four Fe+2.25+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ba2+, one Tb3+, and two Fe+2.25+ atoms. In the third O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ba2+, one Tb3+, and two equivalent Fe+2.25+ atoms.