Materials Data on SrLa2Fe2O7 by Materials Project
La2SrFe2O7 crystallizes in the tetragonal I4mm space group. The structure is three-dimensional. Sr2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.42–2.83 Å. There are two inequivalent La3+ sites. In the first La3+ site, La3+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of La–O bond distances ranging from 2.34–2.82 Å. In the second La3+ site, La3+ is bonded to twelve O2- atoms to form LaO12 cuboctahedra that share corners with four equivalent LaO12 cuboctahedra, faces with four equivalent LaO12 cuboctahedra, and faces with eight FeO6 octahedra. There are a spread of La–O bond distances ranging from 2.67–2.91 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 five FeO6 octahedra and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–2°. There are five shorter (1.98 Å) and one longer (2.09 Å) Fe–O bond lengths. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with five FeO6 octahedra and faces with four equivalent LaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–9°. There are a spread of Fe–O bond distances ranging from 1.98–2.10 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to four La3+ and two equivalent Fe3+ atoms. In the second O2- site, O2- is bonded to two equivalent Sr2+, two equivalent La3+, and two equivalent Fe3+ atoms to form a mixture of distorted edge, face, and corner-sharing OSr2La2Fe2 octahedra. The corner-sharing octahedra tilt angles range from 9–52°. In the third O2- site, O2- is bonded to one Sr2+, four equivalent La3+, and one Fe3+ atom to form distorted OSrLa4Fe octahedra that share corners with eight OSr2La2Fe2 octahedra and edges with eight OSrLa4Fe octahedra. The corner-sharing octahedra tilt angles range from 14–47°. In the fourth O2- site, O2- is bonded to four equivalent Sr2+, one La3+, and one Fe3+ atom to form distorted OSr4LaFe octahedra that share corners with twelve OSr2La2Fe2 octahedra, edges with eight OSrLa4Fe octahedra, and faces with four equivalent OSr2La2Fe2 octahedra. The corner-sharing octahedra tilt angles range from 17–52°. In the fifth O2- site, O2- is bonded in a distorted linear geometry to four equivalent La3+ and two Fe3+ atoms.