DOE OSTI2020
Ti2O3 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are six inequivalent Ti3+ sites. In the first Ti3+ site, Ti3+ is bonded to seven O2- atoms to form distorted TiO7 pentagonal bipyramids that share corners with two TiO6 octahedra, corners with two equivalent TiO7 pentagonal bipyramids, edges with two equivalent TiO6 octahedra, edges with six TiO7 pentagonal bipyramids, and a faceface with one TiO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 36–37°. There are a spread of Ti–O bond distances ranging from 2.07–2.15 Å. In the second Ti3+ site, Ti3+ is bonded to seven O2- atoms to form distorted TiO7 pentagonal bipyramids that share corners with three TiO6 octahedra, corners with two equivalent TiO7 pentagonal bipyramids, edges with two equivalent TiO6 octahedra, edges with six TiO7 pentagonal bipyramids, and a faceface with one TiO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 48–53°. There are a spread of Ti–O bond distances ranging from 2.05–2.24 Å. In the third Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra, corners with three TiO7 pentagonal bipyramids, edges with three TiO6 octahedra, and edges with two equivalent TiO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 15–66°. There are a spread of Ti–O bond distances ranging from 1.97–2.06 Å. In the fourth Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, edges with three TiO6 octahedra, and edges with two equivalent TiO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 15–60°. There are a spread of Ti–O bond distances ranging from 2.01–2.10 Å. In the fifth Ti3+ site, Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, and edges with four equivalent TiO6 octahedra. The corner-sharing octahedra tilt angles range from 60–66°. There are a spread of Ti–O bond distances ranging from 2.02–2.16 Å. In the sixth Ti3+ site, Ti3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ti–O bond distances ranging from 2.01–2.32 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to five Ti3+ atoms to form distorted OTi5 trigonal bipyramids that share corners with seven OTi4 trigonal pyramids, edges with four equivalent OTi5 trigonal bipyramids, and edges with six OTi4 trigonal pyramids. In the second O2- site, O2- is bonded to four Ti3+ atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent OTi5 square pyramids, a cornercorner with one OTi4 tetrahedra, corners with two equivalent OTi5 trigonal bipyramids, corners with eight OTi4 trigonal pyramids, and edges with three equivalent OTi5 trigonal bipyramids. In the third O2- site, O2- is bonded to four Ti3+ atoms to form distorted OTi4 trigonal pyramids that share corners with two equivalent OTi5 square pyramids, corners with five OTi5 trigonal bipyramids, corners with six OTi4 trigonal pyramids, an edgeedge with one OTi5 trigonal bipyramid, and edges with four OTi4 trigonal pyramids. In the fourth O2- site, O2- is bonded to four Ti3+ atoms to form OTi4 trigonal pyramids that share corners with two equivalent OTi5 square pyramids, corners with three OTi5 trigonal bipyramids, corners with six OTi4 trigonal pyramids, an edgeedge with one OTi5 square pyramid, edges with two equivalent OTi5 trigonal bipyramids, and edges with two equivalent OTi4 trigonal pyramids. In the fifth O2- site, O2- is bonded in a rectangular see-saw-like geometry to four Ti3+ atoms. In the sixth O2- site, O2- is bonded to five Ti3+ atoms to form distorted OTi5 square pyramids that share a cornercorner with one OTi4 tetrahedra, corners with seven OTi4 trigonal pyramids, edges with two equivalent OTi5 square pyramids, edges with two equivalent OTi4 tetrahedra, edges with two equivalent OTi5 trigonal bipyramids, and an edgeedge with one OTi4 trigonal pyramid. In the seventh O2- site, O2- is bonded to four Ti3+ atoms to form distorted OTi4 tetrahedra that share a cornercorner with one OTi5 square pyramid, corners with two equivalent OTi4 tetrahedra, corners with four equivalent OTi5 trigonal bipyramids, corners with four OTi4 trigonal pyramids, edges with two equivalent OTi5 square pyramids, edges with two equivalent OTi4 tetrahedra, and an edgeedge with one OTi5 trigonal bipyramid. In the eighth O2- site, O2- is bonded to five Ti3+ atoms to form distorted OTi5 trigonal bipyramids that share corners with four equivalent OTi4 tetrahedra, corners with five OTi4 trigonal pyramids, edges with two equivalent OTi5 square pyramids, an edgeedge with one OTi4 tetrahedra, edges with two equivalent OTi5 trigonal bipyramids, and edges with three equivalent OTi4 trigonal pyramids. In the ninth O2- site, O2- is bonded to four Ti3+ atoms to form OTi4 trigonal pyramids that share a cornercorner with one OTi5 square pyramid, corners with three equivalent OTi4 tetrahedra, corners with two equivalent OTi5 trigonal bipyramids, corners with two equivalent OTi4 trigonal pyramids, edges with three equivalent OTi5 trigonal bipyramids, and edges with two equivalent OTi4 trigonal pyramids.