The material structure described by La2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded in a 9-coordinate geometry to one O(1), one O(11), one O(13), one O(14), one O(6), one O(7), one O(9), and two equivalent O(8) atoms. In the second La site, La(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(14), one O(2), one O(8), and one O(9) atom. In the third La site, La(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(2), one O(3), one O(6), one O(7), and two equivalent O(5) atoms. In the fourth La site, La(4) is bonded in a 7-coordinate geometry to one O(1), one O(14), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(12), one O(13), one O(14), and one O(8) atom to form corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(10), one O(11), one O(12), and one O(9) atom to form corner-sharing SiO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one La(1), one La(2), one La(4), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one La(2), one La(3), one La(4), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one La(3), one La(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one La(4), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded to one La(4), two equivalent La(3), and one Si(2) atom to form distorted edge-sharing OLa3Si tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one La(1), one La(3), one La(4), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one La(1), one La(3), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one La(1), one La(2), and one Si(4) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one La(2), one La(3), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 1-coordinate geometry to one La(1), one La(2), one La(3), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one La(2), one Si(3), and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one La(1) and one Si(3) atom. In the fourteenth O site, O(14) is bonded in a 1-coordinate geometry to one La(1), one La(2), one La(4), and one Si(3) atom. is represented by the CIF card [CIF]
data_La2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.877
_cell_length_b   6.955
_cell_length_c   12.642
_cell_angle_alpha   83.977
_cell_angle_beta   88.896
_cell_angle_gamma   88.528
_symmetry_Int_Tables_number   1
_cell_volume   601.069
_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  0.924  0.167  0.846  1.0
  La  La1  1  0.076  0.833  0.154  1.0
  La  La2  1  0.324  0.760  0.864  1.0
  La  La3  1  0.676  0.240  0.136  1.0
  La  La4  1  0.629  0.629  0.362  1.0
  La  La5  1  0.371  0.371  0.638  1.0
  La  La6  1  0.757  0.804  0.642  1.0
  La  La7  1  0.243  0.196  0.358  1.0
  Si  Si8  1  0.225  0.893  0.609  1.0
  Si  Si9  1  0.775  0.107  0.391  1.0
  Si  Si10  1  0.840  0.311  0.589  1.0
  Si  Si11  1  0.160  0.689  0.411  1.0
  Si  Si12  1  0.838  0.684  0.908  1.0
  Si  Si13  1  0.162  0.316  0.092  1.0
  Si  Si14  1  0.574  0.721  0.102  1.0
  Si  Si15  1  0.426  0.279  0.898  1.0
  O  O16  1  0.072  0.911  0.709  1.0
  O  O17  1  0.928  0.089  0.291  1.0
  O  O18  1  0.403  0.749  0.655  1.0
  O  O19  1  0.597  0.251  0.345  1.0
  O  O20  1  0.695  0.908  0.453  1.0
  O  O21  1  0.305  0.092  0.547  1.0
  O  O22  1  0.093  0.782  0.523  1.0
  O  O23  1  0.907  0.218  0.477  1.0
  O  O24  1  0.696  0.501  0.555  1.0
  O  O25  1  0.304  0.499  0.445  1.0
  O  O26  1  0.704  0.158  0.664  1.0
  O  O27  1  0.296  0.842  0.336  1.0
  O  O28  1  0.973  0.636  0.345  1.0
  O  O29  1  0.027  0.364  0.655  1.0
  O  O30  1  0.004  0.827  0.948  1.0
  O  O31  1  0.996  0.173  0.052  1.0
  O  O32  1  0.377  0.813  0.048  1.0
  O  O33  1  0.623  0.187  0.952  1.0
  O  O34  1  0.468  0.457  0.806  1.0
  O  O35  1  0.532  0.543  0.194  1.0
  O  O36  1  0.291  0.127  0.843  1.0
  O  O37  1  0.709  0.873  0.157  1.0
  O  O38  1  0.301  0.396  0.987  1.0
  O  O39  1  0.699  0.604  0.013  1.0
  O  O40  1  0.061  0.492  0.147  1.0
  O  O41  1  0.939  0.508  0.853  1.0
  O  O42  1  0.309  0.177  0.171  1.0
  O  O43  1  0.691  0.823  0.829  1.0
[/CIF]
.
The material structure described by La2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent La sites. In the first La site, La(1) is bonded in a 9-coordinate geometry to one O(1), one O(11), one O(13), one O(14), one O(6), one O(7), one O(9), and two equivalent O(8) atoms. In the second La site, La(2) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(14), one O(2), one O(8), and one O(9) atom. In the third La site, La(3) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(2), one O(3), one O(6), one O(7), and two equivalent O(5) atoms. In the fourth La site, La(4) is bonded in a 7-coordinate geometry to one O(1), one O(14), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(12), one O(13), one O(14), and one O(8) atom to form corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(10), one O(11), one O(12), and one O(9) atom to form corner-sharing SiO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one La(1), one La(2), one La(4), and one Si(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one La(2), one La(3), one La(4), and one Si(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one La(3), one La(4), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one La(4), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded to one La(4), two equivalent La(3), and one Si(2) atom to form distorted edge-sharing OLa3Si tetrahedra. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one La(1), one La(3), one La(4), and one Si(2) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one La(1), one La(3), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one La(1), one La(2), and one Si(4) atom. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one La(2), one La(3), and one Si(4) atom. In the eleventh O site, O(11) is bonded in a 1-coordinate geometry to one La(1), one La(2), one La(3), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted bent 120 degrees geometry to one La(2), one Si(3), and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 150 degrees geometry to one La(1) and one Si(3) atom. In the fourteenth O site, O(14) is bonded in a 1-coordinate geometry to one La(1), one La(2), one La(4), and one Si(3) atom. is represented by the CIF card [CIF]
data_La2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.877
_cell_length_b   6.955
_cell_length_c   12.642
_cell_angle_alpha   83.977
_cell_angle_beta   88.896
_cell_angle_gamma   88.528
_symmetry_Int_Tables_number   1
_cell_volume   601.069
_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  0.924  0.167  0.846  1.0
  La  La1  1  0.076  0.833  0.154  1.0
  La  La2  1  0.324  0.760  0.864  1.0
  La  La3  1  0.676  0.240  0.136  1.0
  La  La4  1  0.629  0.629  0.362  1.0
  La  La5  1  0.371  0.371  0.638  1.0
  La  La6  1  0.757  0.804  0.642  1.0
  La  La7  1  0.243  0.196  0.358  1.0
  Si  Si8  1  0.225  0.893  0.609  1.0
  Si  Si9  1  0.775  0.107  0.391  1.0
  Si  Si10  1  0.840  0.311  0.589  1.0
  Si  Si11  1  0.160  0.689  0.411  1.0
  Si  Si12  1  0.838  0.684  0.908  1.0
  Si  Si13  1  0.162  0.316  0.092  1.0
  Si  Si14  1  0.574  0.721  0.102  1.0
  Si  Si15  1  0.426  0.279  0.898  1.0
  O  O16  1  0.072  0.911  0.709  1.0
  O  O17  1  0.928  0.089  0.291  1.0
  O  O18  1  0.403  0.749  0.655  1.0
  O  O19  1  0.597  0.251  0.345  1.0
  O  O20  1  0.695  0.908  0.453  1.0
  O  O21  1  0.305  0.092  0.547  1.0
  O  O22  1  0.093  0.782  0.523  1.0
  O  O23  1  0.907  0.218  0.477  1.0
  O  O24  1  0.696  0.501  0.555  1.0
  O  O25  1  0.304  0.499  0.445  1.0
  O  O26  1  0.704  0.158  0.664  1.0
  O  O27  1  0.296  0.842  0.336  1.0
  O  O28  1  0.973  0.636  0.345  1.0
  O  O29  1  0.027  0.364  0.655  1.0
  O  O30  1  0.004  0.827  0.948  1.0
  O  O31  1  0.996  0.173  0.052  1.0
  O  O32  1  0.377  0.813  0.048  1.0
  O  O33  1  0.623  0.187  0.952  1.0
  O  O34  1  0.468  0.457  0.806  1.0
  O  O35  1  0.532  0.543  0.194  1.0
  O  O36  1  0.291  0.127  0.843  1.0
  O  O37  1  0.709  0.873  0.157  1.0
  O  O38  1  0.301  0.396  0.987  1.0
  O  O39  1  0.699  0.604  0.013  1.0
  O  O40  1  0.061  0.492  0.147  1.0
  O  O41  1  0.939  0.508  0.853  1.0
  O  O42  1  0.309  0.177  0.171  1.0
  O  O43  1  0.691  0.823  0.829  1.0
[/CIF]
.