DOE OSTI2020
Ho10Ti6O27 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are fifteen inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.12–2.58 Å. In the second Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 pentagonal bipyramids that share a cornercorner with one TiO6 octahedra, corners with two equivalent TiO5 square pyramids, a cornercorner with one TiO4 tetrahedra, and edges with two equivalent TiO5 square pyramids. The corner-sharing octahedral tilt angles are 57°. There are a spread of Ho–O bond distances ranging from 2.20–2.55 Å. In the third Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.19–2.40 Å. In the fourth Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.15–2.47 Å. In the fifth Ho3+ site, Ho3+ is bonded to six O2- atoms to form distorted HoO6 octahedra that share a cornercorner with one TiO4 tetrahedra. There are a spread of Ho–O bond distances ranging from 2.14–2.38 Å. In the sixth Ho3+ site, Ho3+ is bonded to six O2- atoms to form distorted HoO6 pentagonal pyramids that share an edgeedge with one HoO8 hexagonal bipyramid and edges with two equivalent TiO6 octahedra. There are a spread of Ho–O bond distances ranging from 2.13–2.44 Å. In the seventh Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.17–2.38 Å. In the eighth Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.20–2.37 Å. In the ninth Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.20–2.88 Å. In the tenth Ho3+ site, Ho3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.23–2.76 Å. In the eleventh Ho3+ site, Ho3+ is bonded to eight O2- atoms to form distorted HoO8 hexagonal bipyramids that share edges with four equivalent TiO6 octahedra, an edgeedge with one HoO6 pentagonal pyramid, and edges with two equivalent TiO5 trigonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.10–2.59 Å. In the twelfth Ho3+ site, Ho3+ is bonded to eight O2- atoms to form distorted HoO8 hexagonal bipyramids that share edges with two equivalent TiO6 octahedra, edges with two equivalent TiO7 pentagonal bipyramids, and edges with two equivalent TiO5 square pyramids. There are a spread of Ho–O bond distances ranging from 2.14–2.60 Å. In the thirteenth Ho3+ site, Ho3+ is bonded to seven O2- atoms to form distorted HoO7 hexagonal pyramids that share a cornercorner with one TiO6 octahedra, corners with two equivalent TiO7 pentagonal bipyramids, and edges with three TiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 63°. There are a spread of Ho–O bond distances ranging from 2.26–2.29 Å. In the fourteenth Ho3+ site, Ho3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ho–O bond distances ranging from 2.19–2.50 Å. In the fifteenth Ho3+ site, Ho3+ is bonded in a 8-coordinate geometry to seven O2- atoms. There are a spread of Ho–O bond distances ranging from 2.31–2.37 Å. There are nine inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to five O2- atoms to form distorted TiO5 square pyramids that share a cornercorner with one TiO6 octahedra, a cornercorner with one HoO7 pentagonal bipyramid, corners with two equivalent TiO5 square pyramids, an edgeedge with one HoO8 hexagonal bipyramid, and an edgeedge with one HoO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 41°. There are a spread of Ti–O bond distances ranging from 1.81–2.16 Å. In the second Ti4+ site, Ti4+ is bonded in a trigonal pyramidal geometry to four O2- atoms. There are a spread of Ti–O bond distances ranging from 1.78–1.95 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with two equivalent TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, corners with two equivalent TiO5 trigonal bipyramids, edges with two equivalent HoO8 hexagonal bipyramids, and an edgeedge with one HoO6 pentagonal pyramid. The corner-sharing octahedra tilt angles range from 42–55°. There are a spread of Ti–O bond distances ranging from 1.80–2.22 Å. In the fourth Ti4+ site, Ti4+ is bonded to four O2- atoms to form distorted TiO4 tetrahedra that share a cornercorner with one HoO6 octahedra and a cornercorner with one HoO7 pentagonal bipyramid. The corner-sharing octahedral tilt angles are 60°. There are a spread of Ti–O bond distances ranging from 1.79–2.03 Å. In the fifth Ti4+ site, Ti4+ is bonded to seven O2- atoms to form distorted TiO7 pentagonal bipyramids that share corners with two equivalent TiO6 octahedra, a cornercorner with one TiO5 trigonal bipyramid, an edgeedge with one HoO7 hexagonal pyramid, and edges with two equivalent TiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ti–O bond distances ranging from 1.92–2.17 Å. In the sixth Ti4+ site, Ti4+ is bonded to five O2- atoms to form distorted TiO5 trigonal bipyramids that share corners with four equivalent TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, and edges with two equivalent HoO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–59°. There are a spread of Ti–O bond distances ranging from 1.79–2.01 Å. In the seventh Ti4+ site, Ti4+ is bonded in a 4-coordinate geometry to four O2- atoms. There are a spread of Ti–O bond distances ranging from 1.87–1.94 Å. In the eighth Ti4+ site, Ti4+ is bonded to seven O2- atoms to form distorted TiO7 pentagonal bipyramids that share a cornercorner with one HoO7 hexagonal pyramid, a cornercorner with one TiO6 octahedra, a cornercorner with one TiO7 pentagonal bipyramid, an edgeedge with one HoO8 hexagonal bipyramid, an edgeedge with one HoO7 hexagonal pyramid, and edges with two TiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 44°. There are a spread of Ti–O bond distances ranging from 1.97–2.15 Å. In the ninth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one HoO7 hexagonal pyramid, a cornercorner with one HoO7 pentagonal bipyramid, corners with two equivalent TiO7 pentagonal bipyramids, corners with two equivalent TiO5 square pyramids, and edges with two equivalent HoO8 hexagonal bipyramids. There are a spread of Ti–O bond distances ranging from 1.89–2.11 Å. There are thirty-eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and one Ti4+ atom. In the second O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OHo3Ti tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the fourth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with four OHo4 tetrahedra and edges with three OHo3Ti tetrahedra. In the fifth O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of edge and corner-sharing OHo4 tetrahedra. In the sixth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with eight OHo3Ti tetrahedra and edges with two equivalent OHo4 tetrahedra. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to one Ho3+ and one Ti4+ atom. In the eighth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OHo3Ti tetrahedra. In the ninth O2- site, O2- is bonded to four Ho3+ atoms to form distorted OHo4 tetrahedra that share corners with seven OHo4 tetrahedra and edges with four OHo3Ti tetrahedra. In the tenth O2- site, O2- is bonded to two Ho3+ and two Ti4+ atoms to form OHo2Ti2 tetrahedra that share corners with eight OHo4 tetrahedra and edges with three OHoTi3 tetrahedra. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and two equivalent Ti4+ atoms. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the thirteenth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of distorted edge and corner-sharing OHo3Ti tetrahedra. In the fourteenth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with six OHo4 tetrahedra and edges with three OHo3Ti tetrahedra. In the fifteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Ho3+ and one Ti4+ atom. In the sixteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ho3+ atoms. In the seventeenth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with three OHo4 tetrahedra and an edgeedge with one OHo3Ti tetrahedra. In the eighteenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the nineteenth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with six OHo4 tetrahedra and edges with three OHo2Ti2 tetrahedra. In the twentieth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ho3+ and two Ti4+ atoms. In the twenty-first O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with nine OHo3Ti tetrahedra and edges with five OHo4 tetrahedra. In the twenty-second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two Ti4+ atoms. In the twenty-third O2- site, O2- is bonded to two Ho3+ and two equivalent Ti4+ atoms to form distorted OHo2Ti2 tetrahedra that share corners with eight OHo4 tetrahedra and edges with four OHoTi3 tetrahedra. In the twenty-fourth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form OHo3Ti tetrahedra that share corners with eight OHo4 tetrahedra and edges with four OHoTi3 tetrahedra. In the twenty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two equivalent Ti4+ atoms. In the twenty-sixth O2- site, O2- is bonded in a 1-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the twenty-seventh O2- site, O2- is bonded to four Ho3+ atoms to form a mixture of edge and corner-sharing OHo4 tetrahedra. In the twenty-eighth O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form a mixture of edge and corner-sharing OHo3Ti tetrahedra. In the twenty-ninth O2- site, O2- is bonded to four Ho3+ atoms to form OHo4 tetrahedra that share corners with six OHo4 tetrahedra and edges with four OHo3Ti tetrahedra. In the thirtieth O2- site, O2- is bonded in a 3-coordinate geometry to two Ho3+ and one Ti4+ atom. In the thirty-first O2- site, O2- is bonded in a 4-coordinate geometry to three Ho3+ and one Ti4+ atom. In the thirty-second O2- site, O2- is bonded to three Ho3+ and one Ti4+ atom to form distorted OHo3Ti tetrahedra that share corners with seven OHo3Ti tetrahedra and an edgeedge with one OHo4 tetrahedra. In the thirty-third O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two equivalent Ti4+ atoms. In the thirty-fourth O2- site, O2- is bonded to four Ho3+ atoms to form corner-sharing OHo4 tetrahedra. In the thirty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two Ti4+ atoms. In the thirty-sixth O2- site, O2- is bonded to one Ho3+ and three Ti4+ atoms to form a mixture of edge and corner-sharing OHoTi3 tetrahedra. In the thirty-seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Ho3+ and two equivalent Ti4+