The compound described by Ho2Ti2O7 crystallizes in the monoclinic P2_1 space group. There are four inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(4), one O(9), two equivalent O(13), and two equivalent O(6) atoms. In the second Ho site, Ho(2) is bonded in a 7-coordinate geometry to one O(12), one O(3), one O(8), two equivalent O(2), and two equivalent O(5) atoms. In the third Ho site, Ho(3) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(13), one O(14), one O(6), one O(7), and one O(9) atom. In the fourth Ho site, Ho(4) is bonded in a 8-coordinate geometry to one O(10), one O(14), one O(2), one O(5), one O(7), one O(8), and two equivalent O(12) atoms. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(5), and one O(7) atom to form corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 32-46°. In the second Ti site, Ti(2) is bonded to one O(1), one O(11), one O(4), one O(7), and two equivalent O(6) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 28-46°. In the third Ti site, Ti(3) is bonded to one O(10), one O(12), one O(14), one O(3), one O(8), and one O(9) atom to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 32-51°. In the fourth Ti site, Ti(4) is bonded to one O(11), one O(14), one O(4), one O(9), and two equivalent O(13) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 27-51°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded to one Ho(1), one Ho(3), one Ti(1), and one Ti(2) atom to form distorted OHo2Ti2 tetrahedra that share  a cornercorner with one O(11)Ho2Ti2 tetrahedra,  a cornercorner with one O(2)Ho3Ti tetrahedra,  a cornercorner with one O(5)Ho3Ti tetrahedra, corners with two equivalent O(9)Ho2Ti2 tetrahedra, and  an edgeedge with one O(11)Ho2Ti2 tetrahedra. In the second O site, O(2) is bonded to one Ho(4), two equivalent Ho(2), and one Ti(1) atom to form distorted OHo3Ti tetrahedra that share  a cornercorner with one O(1)Ho2Ti2 tetrahedra, corners with two equivalent O(12)Ho3Ti tetrahedra, corners with two equivalent O(2)Ho3Ti tetrahedra,  an edgeedge with one O(12)Ho3Ti tetrahedra, and edges with three equivalent O(5)Ho3Ti tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ho(2), one Ti(1), and one Ti(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ho(1), one Ti(2), and one Ti(4) atom. In the fifth O site, O(5) is bonded to one Ho(4), two equivalent Ho(2), and one Ti(1) atom to form distorted OHo3Ti tetrahedra that share  a cornercorner with one O(1)Ho2Ti2 tetrahedra, corners with two equivalent O(5)Ho3Ti tetrahedra, corners with four equivalent O(12)Ho3Ti tetrahedra, and edges with three equivalent O(2)Ho3Ti tetrahedra. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Ho(3), two equivalent Ho(1), and two equivalent Ti(2) atoms. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Ho(3), one Ho(4), one Ti(1), and one Ti(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ho(2), one Ho(4), and one Ti(3) atom. In the ninth O site, O(9) is bonded to one Ho(1), one Ho(3), one Ti(3), and one Ti(4) atom to form distorted OHo2Ti2 tetrahedra that share  a cornercorner with one O(11)Ho2Ti2 tetrahedra,  a cornercorner with one O(12)Ho3Ti tetrahedra, corners with two equivalent O(1)Ho2Ti2 tetrahedra, and  an edgeedge with one O(11)Ho2Ti2 tetrahedra. In the tenth O site, O(10) is bonded in a distorted see-saw-like geometry to one Ho(3), one Ho(4), one Ti(1), and one Ti(3) atom. In the eleventh O site, O(11) is bonded to one Ho(1), one Ho(3), one Ti(2), and one Ti(4) atom to form a mixture of distorted corner and edge-sharing OHo2Ti2 tetrahedra. In the twelfth O site, O(12) is bonded to one Ho(2), two equivalent Ho(4), and one Ti(3) atom to form distorted OHo3Ti tetrahedra that share  a cornercorner with one O(9)Ho2Ti2 tetrahedra, corners with two equivalent O(12)Ho3Ti tetrahedra, corners with two equivalent O(2)Ho3Ti tetrahedra, corners with four equivalent O(5)Ho3Ti tetrahedra, and  an edgeedge with one O(2)Ho3Ti tetrahedra. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one Ho(3), two equivalent Ho(1), and two equivalent Ti(4) atoms. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Ho(3), one Ho(4), one Ti(3), and one Ti(4) atom. is represented by the CIF file [CIF]
data_Ho2Ti2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.285
_cell_length_b   7.455
_cell_length_c   13.052
_cell_angle_alpha   81.651
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   508.866
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ho  Ho0  1  0.773  0.766  0.924  1.0
  Ho  Ho1  1  0.357  0.859  0.563  1.0
  Ho  Ho2  1  0.247  0.715  0.133  1.0
  Ho  Ho3  1  0.779  0.645  0.387  1.0
  Ho  Ho4  1  0.279  0.355  0.613  1.0
  Ho  Ho5  1  0.747  0.285  0.867  1.0
  Ho  Ho6  1  0.857  0.141  0.437  1.0
  Ho  Ho7  1  0.273  0.234  0.076  1.0
  Ti  Ti8  1  0.283  0.929  0.321  1.0
  Ti  Ti9  1  0.768  0.970  0.122  1.0
  Ti  Ti10  1  0.793  0.590  0.673  1.0
  Ti  Ti11  1  0.267  0.531  0.874  1.0
  Ti  Ti12  1  0.767  0.469  0.126  1.0
  Ti  Ti13  1  0.293  0.410  0.327  1.0
  Ti  Ti14  1  0.268  0.030  0.878  1.0
  Ti  Ti15  1  0.783  0.071  0.679  1.0
  O  O16  1  0.433  0.992  0.179  1.0
  O  O17  1  0.563  0.927  0.408  1.0
  O  O18  1  0.670  0.828  0.684  1.0
  O  O19  1  0.353  0.779  0.884  1.0
  O  O20  1  0.066  0.859  0.432  1.0
  O  O21  1  0.043  0.940  0.024  1.0
  O  O22  1  0.955  0.871  0.233  1.0
  O  O23  1  0.099  0.635  0.617  1.0
  O  O24  1  0.931  0.579  0.823  1.0
  O  O25  1  0.381  0.674  0.304  1.0
  O  O26  1  0.652  0.728  0.090  1.0
  O  O27  1  0.589  0.587  0.552  1.0
  O  O28  1  0.540  0.453  0.974  1.0
  O  O29  1  0.456  0.486  0.764  1.0
  O  O30  1  0.956  0.514  0.236  1.0
  O  O31  1  0.040  0.547  0.026  1.0
  O  O32  1  0.089  0.413  0.448  1.0
  O  O33  1  0.152  0.272  0.910  1.0
  O  O34  1  0.881  0.326  0.696  1.0
  O  O35  1  0.431  0.421  0.177  1.0
  O  O36  1  0.599  0.365  0.383  1.0
  O  O37  1  0.455  0.129  0.767  1.0
  O  O38  1  0.543  0.060  0.976  1.0
  O  O39  1  0.566  0.141  0.568  1.0
  O  O40  1  0.853  0.221  0.116  1.0
  O  O41  1  0.170  0.172  0.316  1.0
  O  O42  1  0.063  0.073  0.592  1.0
  O  O43  1  0.933  0.008  0.821  1.0
[/CIF]
.
The compound described by Ho2Ti2O7 crystallizes in the monoclinic P2_1 space group. There are four inequivalent Ho sites. In the first Ho site, Ho(1) is bonded in a 8-coordinate geometry to one O(1), one O(11), one O(4), one O(9), two equivalent O(13), and two equivalent O(6) atoms. In the second Ho site, Ho(2) is bonded in a 7-coordinate geometry to one O(12), one O(3), one O(8), two equivalent O(2), and two equivalent O(5) atoms. In the third Ho site, Ho(3) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(13), one O(14), one O(6), one O(7), and one O(9) atom. In the fourth Ho site, Ho(4) is bonded in a 8-coordinate geometry to one O(10), one O(14), one O(2), one O(5), one O(7), one O(8), and two equivalent O(12) atoms. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(10), one O(2), one O(3), one O(5), and one O(7) atom to form corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 32-46°. In the second Ti site, Ti(2) is bonded to one O(1), one O(11), one O(4), one O(7), and two equivalent O(6) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 28-46°. In the third Ti site, Ti(3) is bonded to one O(10), one O(12), one O(14), one O(3), one O(8), and one O(9) atom to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 32-51°. In the fourth Ti site, Ti(4) is bonded to one O(11), one O(14), one O(4), one O(9), and two equivalent O(13) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 27-51°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded to one Ho(1), one Ho(3), one Ti(1), and one Ti(2) atom to form distorted OHo2Ti2 tetrahedra that share  a cornercorner with one O(11)Ho2Ti2 tetrahedra,  a cornercorner with one O(2)Ho3Ti tetrahedra,  a cornercorner with one O(5)Ho3Ti tetrahedra, corners with two equivalent O(9)Ho2Ti2 tetrahedra, and  an edgeedge with one O(11)Ho2Ti2 tetrahedra. In the second O site, O(2) is bonded to one Ho(4), two equivalent Ho(2), and one Ti(1) atom to form distorted OHo3Ti tetrahedra that share  a cornercorner with one O(1)Ho2Ti2 tetrahedra, corners with two equivalent O(12)Ho3Ti tetrahedra, corners with two equivalent O(2)Ho3Ti tetrahedra,  an edgeedge with one O(12)Ho3Ti tetrahedra, and edges with three equivalent O(5)Ho3Ti tetrahedra. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ho(2), one Ti(1), and one Ti(3) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Ho(1), one Ti(2), and one Ti(4) atom. In the fifth O site, O(5) is bonded to one Ho(4), two equivalent Ho(2), and one Ti(1) atom to form distorted OHo3Ti tetrahedra that share  a cornercorner with one O(1)Ho2Ti2 tetrahedra, corners with two equivalent O(5)Ho3Ti tetrahedra, corners with four equivalent O(12)Ho3Ti tetrahedra, and edges with three equivalent O(2)Ho3Ti tetrahedra. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Ho(3), two equivalent Ho(1), and two equivalent Ti(2) atoms. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Ho(3), one Ho(4), one Ti(1), and one Ti(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ho(2), one Ho(4), and one Ti(3) atom. In the ninth O site, O(9) is bonded to one Ho(1), one Ho(3), one Ti(3), and one Ti(4) atom to form distorted OHo2Ti2 tetrahedra that share  a cornercorner with one O(11)Ho2Ti2 tetrahedra,  a cornercorner with one O(12)Ho3Ti tetrahedra, corners with two equivalent O(1)Ho2Ti2 tetrahedra, and  an edgeedge with one O(11)Ho2Ti2 tetrahedra. In the tenth O site, O(10) is bonded in a distorted see-saw-like geometry to one Ho(3), one Ho(4), one Ti(1), and one Ti(3) atom. In the eleventh O site, O(11) is bonded to one Ho(1), one Ho(3), one Ti(2), and one Ti(4) atom to form a mixture of distorted corner and edge-sharing OHo2Ti2 tetrahedra. In the twelfth O site, O(12) is bonded to one Ho(2), two equivalent Ho(4), and one Ti(3) atom to form distorted OHo3Ti tetrahedra that share  a cornercorner with one O(9)Ho2Ti2 tetrahedra, corners with two equivalent O(12)Ho3Ti tetrahedra, corners with two equivalent O(2)Ho3Ti tetrahedra, corners with four equivalent O(5)Ho3Ti tetrahedra, and  an edgeedge with one O(2)Ho3Ti tetrahedra. In the thirteenth O site, O(13) is bonded in a 5-coordinate geometry to one Ho(3), two equivalent Ho(1), and two equivalent Ti(4) atoms. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Ho(3), one Ho(4), one Ti(3), and one Ti(4) atom. is represented by the CIF file [CIF]
data_Ho2Ti2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.285
_cell_length_b   7.455
_cell_length_c   13.052
_cell_angle_alpha   81.651
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   508.866
_cell_formula_units_Z   4
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
loop_
 _atom_site_type_symbol
 _atom_site_label
 _atom_site_symmetry_multiplicity
 _atom_site_fract_x
 _atom_site_fract_y
 _atom_site_fract_z
 _atom_site_occupancy
  Ho  Ho0  1  0.773  0.766  0.924  1.0
  Ho  Ho1  1  0.357  0.859  0.563  1.0
  Ho  Ho2  1  0.247  0.715  0.133  1.0
  Ho  Ho3  1  0.779  0.645  0.387  1.0
  Ho  Ho4  1  0.279  0.355  0.613  1.0
  Ho  Ho5  1  0.747  0.285  0.867  1.0
  Ho  Ho6  1  0.857  0.141  0.437  1.0
  Ho  Ho7  1  0.273  0.234  0.076  1.0
  Ti  Ti8  1  0.283  0.929  0.321  1.0
  Ti  Ti9  1  0.768  0.970  0.122  1.0
  Ti  Ti10  1  0.793  0.590  0.673  1.0
  Ti  Ti11  1  0.267  0.531  0.874  1.0
  Ti  Ti12  1  0.767  0.469  0.126  1.0
  Ti  Ti13  1  0.293  0.410  0.327  1.0
  Ti  Ti14  1  0.268  0.030  0.878  1.0
  Ti  Ti15  1  0.783  0.071  0.679  1.0
  O  O16  1  0.433  0.992  0.179  1.0
  O  O17  1  0.563  0.927  0.408  1.0
  O  O18  1  0.670  0.828  0.684  1.0
  O  O19  1  0.353  0.779  0.884  1.0
  O  O20  1  0.066  0.859  0.432  1.0
  O  O21  1  0.043  0.940  0.024  1.0
  O  O22  1  0.955  0.871  0.233  1.0
  O  O23  1  0.099  0.635  0.617  1.0
  O  O24  1  0.931  0.579  0.823  1.0
  O  O25  1  0.381  0.674  0.304  1.0
  O  O26  1  0.652  0.728  0.090  1.0
  O  O27  1  0.589  0.587  0.552  1.0
  O  O28  1  0.540  0.453  0.974  1.0
  O  O29  1  0.456  0.486  0.764  1.0
  O  O30  1  0.956  0.514  0.236  1.0
  O  O31  1  0.040  0.547  0.026  1.0
  O  O32  1  0.089  0.413  0.448  1.0
  O  O33  1  0.152  0.272  0.910  1.0
  O  O34  1  0.881  0.326  0.696  1.0
  O  O35  1  0.431  0.421  0.177  1.0
  O  O36  1  0.599  0.365  0.383  1.0
  O  O37  1  0.455  0.129  0.767  1.0
  O  O38  1  0.543  0.060  0.976  1.0
  O  O39  1  0.566  0.141  0.568  1.0
  O  O40  1  0.853  0.221  0.116  1.0
  O  O41  1  0.170  0.172  0.316  1.0
  O  O42  1  0.063  0.073  0.592  1.0
  O  O43  1  0.933  0.008  0.821  1.0
[/CIF]
.