Materials Data on Ba3Fe2(Ge2O7)2 by Materials Project
Ba3Fe2Ge4O14 is Esseneite-like structured and crystallizes in the monoclinic C2 space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.68–3.17 Å. In the second Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.59–3.05 Å. There are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO4 tetrahedra and corners with four equivalent GeO4 tetrahedra. There are two shorter (1.99 Å) and four longer (2.11 Å) Fe–O bond lengths. In the second Fe3+ site, Fe3+ is bonded to four O2- atoms to form FeO4 tetrahedra that share corners with two equivalent FeO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedral tilt angles are 60°. There is two shorter (1.87 Å) and two longer (2.00 Å) Fe–O bond length. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent FeO6 octahedra and corners with two equivalent GeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–58°. There is two shorter (1.75 Å) and two longer (1.85 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one FeO4 tetrahedra and corners with two equivalent GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.73–1.82 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, one Fe3+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+ and two Fe3+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Ba2+, one Fe3+, and one Ge4+ atom. In the fourth O2- site, O2- is bonded to three Ba2+ and one Ge4+ atom to form distorted corner-sharing OBa3Ge tetrahedra. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to two Ba2+ and two Ge4+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Ba2+, one Fe3+, and one Ge4+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+ and two Ge4+ atoms.