Materials Data on Ti7Al2O15 by Materials Project
Ti7Al2O15 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are four inequivalent Ti+3.43+ sites. In the first Ti+3.43+ site, Ti+3.43+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with six TiO6 octahedra, corners with two equivalent AlO4 tetrahedra, and edges with three equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 0–51°. There are a spread of Ti–O bond distances ranging from 1.99–2.11 Å. In the second Ti+3.43+ site, Ti+3.43+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with four equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 49–51°. There are a spread of Ti–O bond distances ranging from 1.89–2.13 Å. In the third Ti+3.43+ site, Ti+3.43+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with four TiO6 octahedra, corners with three equivalent AlO4 tetrahedra, and edges with four equivalent TiO6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are a spread of Ti–O bond distances ranging from 1.87–2.21 Å. In the fourth Ti+3.43+ site, Ti+3.43+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles are 49°. There are four shorter (2.01 Å) and two longer (2.03 Å) Ti–O bond lengths. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share corners with eight TiO6 octahedra and corners with two equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–63°. There is two shorter (1.75 Å) and two longer (1.81 Å) Al–O bond length. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded to three equivalent Ti+3.43+ and one Al3+ atom to form a mixture of distorted edge and corner-sharing OTi3Al tetrahedra. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Ti+3.43+ and two equivalent Al3+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Ti+3.43+ and one Al3+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ti+3.43+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ti+3.43+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ti+3.43+ atoms. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to three Ti+3.43+ atoms. In the eighth O2- site, O2- is bonded in a square co-planar geometry to four equivalent Ti+3.43+ atoms.