The compound described by La2Si2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), two equivalent O(6), 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(4), one O(6), one O(7), two equivalent O(2), and two equivalent O(3) atoms. There are two 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(5) 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. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(6) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Si(2) atom. In the third O site, O(7) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Si(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(1) atom. In the fifth O site, O(2) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Si(1) atom. In the sixth O site, O(3) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Si(1) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(2) atom. is represented by the CIF file [CIF]
data_La2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.775
_cell_length_b   5.453
_cell_length_c   14.290
_cell_angle_alpha   67.240
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   630.585
_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  0.608  0.168  0.589  1.0
  La  La1  1  0.108  0.832  0.911  1.0
  La  La2  1  0.392  0.832  0.411  1.0
  La  La3  1  0.892  0.168  0.089  1.0
  La  La4  1  0.809  0.484  0.768  1.0
  La  La5  1  0.309  0.516  0.732  1.0
  La  La6  1  0.191  0.516  0.232  1.0
  La  La7  1  0.691  0.484  0.268  1.0
  Si  Si8  1  0.493  0.051  0.180  1.0
  Si  Si9  1  0.993  0.949  0.320  1.0
  Si  Si10  1  0.507  0.949  0.820  1.0
  Si  Si11  1  0.007  0.051  0.680  1.0
  Si  Si12  1  0.245  0.242  0.027  1.0
  Si  Si13  1  0.745  0.758  0.473  1.0
  Si  Si14  1  0.755  0.758  0.973  1.0
  Si  Si15  1  0.255  0.242  0.527  1.0
  O  O16  1  0.671  0.982  0.173  1.0
  O  O17  1  0.171  0.018  0.327  1.0
  O  O18  1  0.329  0.018  0.827  1.0
  O  O19  1  0.829  0.982  0.673  1.0
  O  O20  1  0.415  0.763  0.242  1.0
  O  O21  1  0.915  0.237  0.258  1.0
  O  O22  1  0.585  0.237  0.758  1.0
  O  O23  1  0.085  0.763  0.742  1.0
  O  O24  1  0.469  0.231  0.247  1.0
  O  O25  1  0.969  0.769  0.253  1.0
  O  O26  1  0.531  0.769  0.753  1.0
  O  O27  1  0.031  0.231  0.747  1.0
  O  O28  1  0.238  0.421  0.907  1.0
  O  O29  1  0.738  0.579  0.593  1.0
  O  O30  1  0.762  0.579  0.093  1.0
  O  O31  1  0.262  0.421  0.407  1.0
  O  O32  1  0.080  0.199  0.567  1.0
  O  O33  1  0.580  0.801  0.933  1.0
  O  O34  1  0.920  0.801  0.433  1.0
  O  O35  1  0.420  0.199  0.067  1.0
  O  O36  1  0.345  0.960  0.558  1.0
  O  O37  1  0.845  0.040  0.942  1.0
  O  O38  1  0.655  0.040  0.442  1.0
  O  O39  1  0.155  0.960  0.058  1.0
  O  O40  1  0.355  0.413  0.579  1.0
  O  O41  1  0.855  0.587  0.921  1.0
  O  O42  1  0.645  0.587  0.421  1.0
  O  O43  1  0.145  0.413  0.079  1.0
[/CIF]
.
The compound described by La2Si2O7 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent La sites. In the first La site, La(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(3), one O(4), two equivalent O(6), 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(4), one O(6), one O(7), two equivalent O(2), and two equivalent O(3) atoms. There are two 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(5) 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. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the second O site, O(6) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Si(2) atom. In the third O site, O(7) is bonded in a 4-coordinate geometry to one La(2), two equivalent La(1), and one Si(2) atom. In the fourth O site, O(1) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(1) atom. In the fifth O site, O(2) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Si(1) atom. In the sixth O site, O(3) is bonded in a 4-coordinate geometry to one La(1), two equivalent La(2), and one Si(1) atom. In the seventh O site, O(4) is bonded in a 3-coordinate geometry to one La(1), one La(2), and one Si(2) atom. is represented by the CIF file [CIF]
data_La2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.775
_cell_length_b   5.453
_cell_length_c   14.290
_cell_angle_alpha   67.240
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   630.585
_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  0.608  0.168  0.589  1.0
  La  La1  1  0.108  0.832  0.911  1.0
  La  La2  1  0.392  0.832  0.411  1.0
  La  La3  1  0.892  0.168  0.089  1.0
  La  La4  1  0.809  0.484  0.768  1.0
  La  La5  1  0.309  0.516  0.732  1.0
  La  La6  1  0.191  0.516  0.232  1.0
  La  La7  1  0.691  0.484  0.268  1.0
  Si  Si8  1  0.493  0.051  0.180  1.0
  Si  Si9  1  0.993  0.949  0.320  1.0
  Si  Si10  1  0.507  0.949  0.820  1.0
  Si  Si11  1  0.007  0.051  0.680  1.0
  Si  Si12  1  0.245  0.242  0.027  1.0
  Si  Si13  1  0.745  0.758  0.473  1.0
  Si  Si14  1  0.755  0.758  0.973  1.0
  Si  Si15  1  0.255  0.242  0.527  1.0
  O  O16  1  0.671  0.982  0.173  1.0
  O  O17  1  0.171  0.018  0.327  1.0
  O  O18  1  0.329  0.018  0.827  1.0
  O  O19  1  0.829  0.982  0.673  1.0
  O  O20  1  0.415  0.763  0.242  1.0
  O  O21  1  0.915  0.237  0.258  1.0
  O  O22  1  0.585  0.237  0.758  1.0
  O  O23  1  0.085  0.763  0.742  1.0
  O  O24  1  0.469  0.231  0.247  1.0
  O  O25  1  0.969  0.769  0.253  1.0
  O  O26  1  0.531  0.769  0.753  1.0
  O  O27  1  0.031  0.231  0.747  1.0
  O  O28  1  0.238  0.421  0.907  1.0
  O  O29  1  0.738  0.579  0.593  1.0
  O  O30  1  0.762  0.579  0.093  1.0
  O  O31  1  0.262  0.421  0.407  1.0
  O  O32  1  0.080  0.199  0.567  1.0
  O  O33  1  0.580  0.801  0.933  1.0
  O  O34  1  0.920  0.801  0.433  1.0
  O  O35  1  0.420  0.199  0.067  1.0
  O  O36  1  0.345  0.960  0.558  1.0
  O  O37  1  0.845  0.040  0.942  1.0
  O  O38  1  0.655  0.040  0.442  1.0
  O  O39  1  0.155  0.960  0.058  1.0
  O  O40  1  0.355  0.413  0.579  1.0
  O  O41  1  0.855  0.587  0.921  1.0
  O  O42  1  0.645  0.587  0.421  1.0
  O  O43  1  0.145  0.413  0.079  1.0
[/CIF]
.