Materials Data on Ti6Fe8O21 by Materials Project
Ti6Fe8O21 is Ilmenite-like structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are six inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.81–2.34 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with nine FeO6 octahedra, edges with three TiO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 43–62°. There are a spread of Ti–O bond distances ranging from 1.89–2.16 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with nine FeO6 octahedra, an edgeedge with one FeO6 octahedra, edges with two TiO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–62°. There are a spread of Ti–O bond distances ranging from 1.86–2.23 Å. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with nine FeO6 octahedra, edges with two TiO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 47–59°. There are a spread of Ti–O bond distances ranging from 1.89–2.20 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with nine FeO6 octahedra, an edgeedge with one FeO6 octahedra, edges with two TiO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 42–63°. There are a spread of Ti–O bond distances ranging from 1.80–2.24 Å. In the sixth Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with nine FeO6 octahedra, edges with two TiO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–63°. There are a spread of Ti–O bond distances ranging from 1.87–2.12 Å. There are eight inequivalent Fe+2.25+ sites. In the first Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share a cornercorner with one FeO6 octahedra, corners with six TiO6 octahedra, edges with three FeO6 octahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedra tilt angles range from 42–65°. There are a spread of Fe–O bond distances ranging from 2.02–2.28 Å. In the second Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share a cornercorner with one FeO6 octahedra, corners with six TiO6 octahedra, edges with three FeO6 octahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedra tilt angles range from 47–62°. There are a spread of Fe–O bond distances ranging from 2.08–2.24 Å. In the third Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with nine FeO6 octahedra, edges with two TiO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–66°. There are a spread of Fe–O bond distances ranging from 2.03–2.26 Å. In the fourth Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with eight TiO6 octahedra, edges with three FeO6 octahedra, and a faceface with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 45–62°. There are a spread of Fe–O bond distances ranging from 2.07–2.31 Å. In the fifth Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TiO6 octahedra, edges with three FeO6 octahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedra tilt angles range from 47–59°. There are a spread of Fe–O bond distances ranging from 2.08–2.28 Å. In the sixth Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TiO6 octahedra, and edges with three FeO6 octahedra. The corner-sharing octahedra tilt angles range from 40–64°. There are a spread of Fe–O bond distances ranging from 1.98–2.23 Å. In the seventh Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with six TiO6 octahedra, edges with three FeO6 octahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedra tilt angles range from 42–66°. There are a spread of Fe–O bond distances ranging from 1.99–2.22 Å. In the eighth Fe+2.25+ site, Fe+2.25+ is bonded to six O2- atoms to form distorted FeO6 octahedra that share a cornercorner with one FeO6 octahedra, corners with seven TiO6 octahedra, edges with three FeO6 octahedra, and a faceface with one TiO6 octahedra. The corner-sharing octahedra tilt angles range from 40–63°. There are a spread of Fe–O bond distances ranging from 2.05–2.25 Å. There are twenty-one inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted see-saw-like geometry to two equivalent Ti4+ and two Fe+2.25+ atoms. In the second O2- site, O2- is bonded to two Ti4+ and two equivalent Fe+2.25+ atoms to form a mixture of distorted edge and corner-sharing OTi2Fe2 trigonal pyramids. In the third O2- site, O2- is bonded in a distorted see-saw-like geometry to two Ti4+ and two Fe+2.25+ atoms. In the fourth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Ti4+ and two Fe+2.25+ atoms. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ti4+ and two Fe+2.25+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Ti4+ and two Fe+2.25+ atoms. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to one Ti4+ and three Fe+2.25+ atoms. In the eighth O2- site, O2- is bonded in a distorted see-saw-like geometry to one Ti4+ and three Fe+2.25+ atoms. In the ninth O2- site, O2- is bonded to two Ti4+ and two Fe+2.25+ atoms to form distorted OTi2Fe2 trigonal pyramids that share corners with two OTiFe3 trigonal pyramids and edges with two OTi2Fe2 trigonal pyramids. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ti4+ and two Fe+2.25+ atoms. In the eleventh O2- site, O2- is bonded to one Ti4+ and three Fe+2.25+ atoms to form distorted corner-sharing OTiFe3 trigonal pyramids. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Ti4+ and two Fe+2.25+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ti4+ and three Fe+2.25+ atoms. In the fourteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Ti4+ and three Fe+2.25+ atoms. In the fifteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Ti4+ and two Fe+2.25+ atoms. In the sixteenth O2- site, O2- is bonded to two Ti4+ and two Fe+2.25+ atoms to form distorted OTi2Fe2 trigonal pyramids that share corners with two OTiFe3 trigonal pyramids and an edgeedge with one OTi2Fe2 trigonal pyramid. In the seventeenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ti4+ and two Fe+2.25+ atoms. In the eighteenth O2- site, O2- is bonded in a distorted see-saw-like geometry to two Ti4+ and two Fe+2.25+ atoms. In the nineteenth O2- site, O2- is bonded to two Ti4+ and two Fe+2.25+ atoms to form a mixture of distorted edge and corner-sharing OTi2Fe2 trigonal pyramids. In the twentieth O2- site, O2- is bonded in a distorted see-saw-like geometry to one Ti4+ and three Fe+2.25+ atoms. In the twenty-first O2- site, O2- is bonded to two equivalent Ti4+ and two Fe+2.25+ atoms to form a mixture of distorted edge and corner-sharing OTi2Fe2 trigonal pyramids.