The material structure described by La2Ti2O7 is Pb (Zr_0.50 Ti_0.48) O_3-like structured and crystallizes in the monoclinic P2_1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(9), two equivalent O(1), and two equivalent O(7) atoms. In the second La site, La(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(14), one O(6), one O(7), one O(9), and two equivalent O(4) atoms. In the third La site, La(3) is bonded in a 9-coordinate geometry to one O(12), one O(13), one O(2), one O(3), one O(5), two equivalent O(11), and two equivalent O(8) atoms. In the fourth La site, La(4) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(3), one O(5), one O(6), and one O(8) atom. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(10), one O(12), one O(14), one O(2), one O(4), and one O(9) atom to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 17-40°. In the second Ti site, Ti(2) is bonded to one O(13), one O(3), one O(5), one O(6), and two equivalent O(11) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 15-36°. In the third Ti site, Ti(3) is bonded to one O(12), one O(13), one O(14), one O(5), and two equivalent O(8) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 15-40°. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(10), one O(2), one O(3), one O(6), and one O(7) atom to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 17-36°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded to one La(2), two equivalent La(1), and one Ti(4) atom to form distorted OLa3Ti tetrahedra that share  a cornercorner with one O(3)La2Ti2 tetrahedra, corners with two equivalent O(1)La3Ti tetrahedra, corners with four equivalent O(4)La3Ti tetrahedra, and edges with three equivalent O(7)La3Ti tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one La(1), one La(3), one Ti(1), and one Ti(4) atom. In the third O site, O(3) is bonded to one La(3), one La(4), one Ti(2), and one Ti(4) atom to form distorted OLa2Ti2 tetrahedra that share  a cornercorner with one O(1)La3Ti tetrahedra,  a cornercorner with one O(7)La3Ti tetrahedra, and corners with two equivalent O(12)La2Ti2 tetrahedra. In the fourth O site, O(4) is bonded to one La(1), two equivalent La(2), and one Ti(1) atom to form distorted OLa3Ti tetrahedra that share  a cornercorner with one O(12)La2Ti2 tetrahedra, corners with two equivalent O(4)La3Ti tetrahedra, corners with two equivalent O(7)La3Ti tetrahedra, corners with four equivalent O(1)La3Ti tetrahedra, and  an edgeedge with one O(7)La3Ti tetrahedra. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one La(3), one La(4), one Ti(2), and one Ti(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one La(2), one La(4), one Ti(2), and one Ti(4) atom. In the seventh O site, O(7) is bonded to one La(2), two equivalent La(1), and one Ti(4) atom to form distorted OLa3Ti tetrahedra that share  a cornercorner with one O(3)La2Ti2 tetrahedra, corners with two equivalent O(4)La3Ti tetrahedra, corners with two equivalent O(7)La3Ti tetrahedra,  an edgeedge with one O(4)La3Ti tetrahedra, and edges with three equivalent O(1)La3Ti tetrahedra. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one La(4), two equivalent La(3), and two equivalent Ti(3) atoms. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Ti(1) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one La(2), one La(4), one Ti(1), and one Ti(4) atom. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one La(4), two equivalent La(3), and two equivalent Ti(2) atoms. In the twelfth O site, O(12) is bonded to one La(3), one La(4), one Ti(1), and one Ti(3) atom to form distorted OLa2Ti2 tetrahedra that share  a cornercorner with one O(4)La3Ti tetrahedra and corners with two equivalent O(3)La2Ti2 tetrahedra. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one La(3), one La(4), one Ti(2), and one Ti(3) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one La(2), one La(4), one Ti(1), and one Ti(3) atom. is represented by the CIF card [CIF]
data_La2Ti2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.544
_cell_length_b   7.777
_cell_length_c   13.064
_cell_angle_alpha   98.572
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   557.009
_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
  La  La0  1  0.346  0.147  0.581  1.0
  La  La1  1  0.846  0.853  0.419  1.0
  La  La2  1  0.301  0.650  0.610  1.0
  La  La3  1  0.260  0.773  0.098  1.0
  La  La4  1  0.255  0.279  0.115  1.0
  La  La5  1  0.801  0.350  0.390  1.0
  La  La6  1  0.755  0.721  0.885  1.0
  La  La7  1  0.760  0.227  0.902  1.0
  Ti  Ti8  1  0.797  0.418  0.675  1.0
  Ti  Ti9  1  0.766  0.031  0.118  1.0
  Ti  Ti10  1  0.264  0.474  0.880  1.0
  Ti  Ti11  1  0.793  0.923  0.678  1.0
  Ti  Ti12  1  0.266  0.969  0.882  1.0
  Ti  Ti13  1  0.764  0.526  0.120  1.0
  Ti  Ti14  1  0.297  0.582  0.325  1.0
  Ti  Ti15  1  0.293  0.077  0.322  1.0
  O  O16  1  0.573  0.877  0.570  1.0
  O  O17  1  0.073  0.123  0.430  1.0
  O  O18  1  0.715  0.175  0.695  1.0
  O  O19  1  0.956  0.972  0.814  1.0
  O  O20  1  0.084  0.596  0.439  1.0
  O  O21  1  0.190  0.727  0.907  1.0
  O  O22  1  0.468  0.897  0.774  1.0
  O  O23  1  0.055  0.914  0.592  1.0
  O  O24  1  0.524  0.525  0.981  1.0
  O  O25  1  0.024  0.475  0.019  1.0
  O  O26  1  0.072  0.383  0.604  1.0
  O  O27  1  0.456  0.028  0.186  1.0
  O  O28  1  0.332  0.327  0.308  1.0
  O  O29  1  0.524  0.966  0.983  1.0
  O  O30  1  0.951  0.438  0.816  1.0
  O  O31  1  0.690  0.273  0.093  1.0
  O  O32  1  0.968  0.103  0.226  1.0
  O  O33  1  0.572  0.617  0.396  1.0
  O  O34  1  0.803  0.776  0.107  1.0
  O  O35  1  0.962  0.509  0.229  1.0
  O  O36  1  0.024  0.034  0.017  1.0
  O  O37  1  0.832  0.673  0.692  1.0
  O  O38  1  0.451  0.562  0.184  1.0
  O  O39  1  0.555  0.086  0.408  1.0
  O  O40  1  0.584  0.404  0.561  1.0
  O  O41  1  0.303  0.224  0.893  1.0
  O  O42  1  0.215  0.825  0.305  1.0
  O  O43  1  0.462  0.491  0.771  1.0
[/CIF]
.
The material structure described by La2Ti2O7 is Pb (Zr_0.50 Ti_0.48) O_3-like structured and crystallizes in the monoclinic P2_1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(9), two equivalent O(1), and two equivalent O(7) atoms. In the second La site, La(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(14), one O(6), one O(7), one O(9), and two equivalent O(4) atoms. In the third La site, La(3) is bonded in a 9-coordinate geometry to one O(12), one O(13), one O(2), one O(3), one O(5), two equivalent O(11), and two equivalent O(8) atoms. In the fourth La site, La(4) is bonded in a 9-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(3), one O(5), one O(6), and one O(8) atom. There are four inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(10), one O(12), one O(14), one O(2), one O(4), and one O(9) atom to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 17-40°. In the second Ti site, Ti(2) is bonded to one O(13), one O(3), one O(5), one O(6), and two equivalent O(11) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 15-36°. In the third Ti site, Ti(3) is bonded to one O(12), one O(13), one O(14), one O(5), and two equivalent O(8) atoms to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 15-40°. In the fourth Ti site, Ti(4) is bonded to one O(1), one O(10), one O(2), one O(3), one O(6), and one O(7) atom to form distorted corner-sharing TiO6 octahedra. The corner-sharing octahedral tilt angles range from 17-36°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded to one La(2), two equivalent La(1), and one Ti(4) atom to form distorted OLa3Ti tetrahedra that share  a cornercorner with one O(3)La2Ti2 tetrahedra, corners with two equivalent O(1)La3Ti tetrahedra, corners with four equivalent O(4)La3Ti tetrahedra, and edges with three equivalent O(7)La3Ti tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one La(1), one La(3), one Ti(1), and one Ti(4) atom. In the third O site, O(3) is bonded to one La(3), one La(4), one Ti(2), and one Ti(4) atom to form distorted OLa2Ti2 tetrahedra that share  a cornercorner with one O(1)La3Ti tetrahedra,  a cornercorner with one O(7)La3Ti tetrahedra, and corners with two equivalent O(12)La2Ti2 tetrahedra. In the fourth O site, O(4) is bonded to one La(1), two equivalent La(2), and one Ti(1) atom to form distorted OLa3Ti tetrahedra that share  a cornercorner with one O(12)La2Ti2 tetrahedra, corners with two equivalent O(4)La3Ti tetrahedra, corners with two equivalent O(7)La3Ti tetrahedra, corners with four equivalent O(1)La3Ti tetrahedra, and  an edgeedge with one O(7)La3Ti tetrahedra. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one La(3), one La(4), one Ti(2), and one Ti(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one La(2), one La(4), one Ti(2), and one Ti(4) atom. In the seventh O site, O(7) is bonded to one La(2), two equivalent La(1), and one Ti(4) atom to form distorted OLa3Ti tetrahedra that share  a cornercorner with one O(3)La2Ti2 tetrahedra, corners with two equivalent O(4)La3Ti tetrahedra, corners with two equivalent O(7)La3Ti tetrahedra,  an edgeedge with one O(4)La3Ti tetrahedra, and edges with three equivalent O(1)La3Ti tetrahedra. In the eighth O site, O(8) is bonded in a 5-coordinate geometry to one La(4), two equivalent La(3), and two equivalent Ti(3) atoms. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Ti(1) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one La(2), one La(4), one Ti(1), and one Ti(4) atom. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one La(4), two equivalent La(3), and two equivalent Ti(2) atoms. In the twelfth O site, O(12) is bonded to one La(3), one La(4), one Ti(1), and one Ti(3) atom to form distorted OLa2Ti2 tetrahedra that share  a cornercorner with one O(4)La3Ti tetrahedra and corners with two equivalent O(3)La2Ti2 tetrahedra. In the thirteenth O site, O(13) is bonded in a 3-coordinate geometry to one La(3), one La(4), one Ti(2), and one Ti(3) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one La(2), one La(4), one Ti(1), and one Ti(3) atom. is represented by the CIF card [CIF]
data_La2Ti2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.544
_cell_length_b   7.777
_cell_length_c   13.064
_cell_angle_alpha   98.572
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   557.009
_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
  La  La0  1  0.346  0.147  0.581  1.0
  La  La1  1  0.846  0.853  0.419  1.0
  La  La2  1  0.301  0.650  0.610  1.0
  La  La3  1  0.260  0.773  0.098  1.0
  La  La4  1  0.255  0.279  0.115  1.0
  La  La5  1  0.801  0.350  0.390  1.0
  La  La6  1  0.755  0.721  0.885  1.0
  La  La7  1  0.760  0.227  0.902  1.0
  Ti  Ti8  1  0.797  0.418  0.675  1.0
  Ti  Ti9  1  0.766  0.031  0.118  1.0
  Ti  Ti10  1  0.264  0.474  0.880  1.0
  Ti  Ti11  1  0.793  0.923  0.678  1.0
  Ti  Ti12  1  0.266  0.969  0.882  1.0
  Ti  Ti13  1  0.764  0.526  0.120  1.0
  Ti  Ti14  1  0.297  0.582  0.325  1.0
  Ti  Ti15  1  0.293  0.077  0.322  1.0
  O  O16  1  0.573  0.877  0.570  1.0
  O  O17  1  0.073  0.123  0.430  1.0
  O  O18  1  0.715  0.175  0.695  1.0
  O  O19  1  0.956  0.972  0.814  1.0
  O  O20  1  0.084  0.596  0.439  1.0
  O  O21  1  0.190  0.727  0.907  1.0
  O  O22  1  0.468  0.897  0.774  1.0
  O  O23  1  0.055  0.914  0.592  1.0
  O  O24  1  0.524  0.525  0.981  1.0
  O  O25  1  0.024  0.475  0.019  1.0
  O  O26  1  0.072  0.383  0.604  1.0
  O  O27  1  0.456  0.028  0.186  1.0
  O  O28  1  0.332  0.327  0.308  1.0
  O  O29  1  0.524  0.966  0.983  1.0
  O  O30  1  0.951  0.438  0.816  1.0
  O  O31  1  0.690  0.273  0.093  1.0
  O  O32  1  0.968  0.103  0.226  1.0
  O  O33  1  0.572  0.617  0.396  1.0
  O  O34  1  0.803  0.776  0.107  1.0
  O  O35  1  0.962  0.509  0.229  1.0
  O  O36  1  0.024  0.034  0.017  1.0
  O  O37  1  0.832  0.673  0.692  1.0
  O  O38  1  0.451  0.562  0.184  1.0
  O  O39  1  0.555  0.086  0.408  1.0
  O  O40  1  0.584  0.404  0.561  1.0
  O  O41  1  0.303  0.224  0.893  1.0
  O  O42  1  0.215  0.825  0.305  1.0
  O  O43  1  0.462  0.491  0.771  1.0
[/CIF]
.