Materials Data on Ta2Fe4O9 by Materials Project
Fe4Ta2O9 is Ilmenite-like structured and crystallizes in the trigonal P-3c1 space group. The structure is three-dimensional. Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with nine FeO6 octahedra, edges with three equivalent FeO6 octahedra, and a faceface with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 46–57°. There are three shorter (1.92 Å) and three longer (2.14 Å) Ta–O bond lengths. There are two inequivalent Fe2+ sites. In the first Fe2+ site, Fe2+ is bonded to six equivalent O2- atoms to form FeO6 octahedra that share corners with three equivalent FeO6 octahedra, corners with six equivalent TaO6 octahedra, edges with three equivalent FeO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 46–57°. There are three shorter (2.14 Å) and three longer (2.23 Å) Fe–O bond lengths. In the second Fe2+ site, Fe2+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with three equivalent TaO6 octahedra, corners with six FeO6 octahedra, edges with three equivalent TaO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–68°. There are three shorter (2.10 Å) and three longer (2.30 Å) Fe–O bond lengths. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Fe2+ atoms. In the second O2- site, O2- is bonded to two equivalent Ta5+ and two equivalent Fe2+ atoms to form a mixture of distorted edge and corner-sharing OTa2Fe2 trigonal pyramids.