The structure described by Gd2Si2O7 crystallizes in the orthorhombic Pnma space group. Gd(1) is bonded to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form distorted GdO7 pentagonal bipyramids that share corners with three equivalent Gd(1)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Gd(1)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with four equivalent Gd(1)O7 pentagonal bipyramids,  a cornercorner with one Si(2)O4 tetrahedra, and edges with two equivalent Gd(1)O7 pentagonal bipyramids. In the second Si site, Si(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with four equivalent Gd(1)O7 pentagonal bipyramids,  a cornercorner with one Si(1)O4 tetrahedra, and edges with two equivalent Gd(1)O7 pentagonal bipyramids. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Gd(1) and one Si(2) atom. In the second O site, O(5) is bonded in a trigonal planar geometry to two equivalent Gd(1) and one Si(2) atom. In the third O site, O(1) is bonded in a trigonal planar geometry to two equivalent Gd(1) and one Si(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Gd(1) and one Si(1) atom. In the fifth O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Gd(1), one Si(1), and one Si(2) atom. is represented by the CIF card [CIF]
data_Gd2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.067
_cell_length_b   8.289
_cell_length_c   13.871
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   582.490
_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
  Gd  Gd0  1  0.839  0.008  0.125  1.0
  Gd  Gd1  1  0.161  0.508  0.875  1.0
  Gd  Gd2  1  0.661  0.008  0.625  1.0
  Gd  Gd3  1  0.339  0.508  0.375  1.0
  Gd  Gd4  1  0.839  0.492  0.125  1.0
  Gd  Gd5  1  0.161  0.992  0.875  1.0
  Gd  Gd6  1  0.661  0.492  0.625  1.0
  Gd  Gd7  1  0.339  0.992  0.375  1.0
  Si  Si8  1  0.123  0.750  0.539  1.0
  Si  Si9  1  0.877  0.250  0.461  1.0
  Si  Si10  1  0.377  0.750  0.039  1.0
  Si  Si11  1  0.623  0.250  0.961  1.0
  Si  Si12  1  0.878  0.750  0.320  1.0
  Si  Si13  1  0.122  0.250  0.680  1.0
  Si  Si14  1  0.622  0.750  0.820  1.0
  Si  Si15  1  0.378  0.250  0.180  1.0
  O  O16  1  0.850  0.750  0.599  1.0
  O  O17  1  0.150  0.250  0.401  1.0
  O  O18  1  0.650  0.750  0.099  1.0
  O  O19  1  0.350  0.250  0.901  1.0
  O  O20  1  0.289  0.916  0.547  1.0
  O  O21  1  0.711  0.416  0.453  1.0
  O  O22  1  0.211  0.916  0.047  1.0
  O  O23  1  0.789  0.416  0.953  1.0
  O  O24  1  0.289  0.584  0.547  1.0
  O  O25  1  0.711  0.084  0.453  1.0
  O  O26  1  0.211  0.584  0.047  1.0
  O  O27  1  0.789  0.084  0.953  1.0
  O  O28  1  0.059  0.750  0.420  1.0
  O  O29  1  0.941  0.250  0.580  1.0
  O  O30  1  0.441  0.750  0.920  1.0
  O  O31  1  0.559  0.250  0.080  1.0
  O  O32  1  0.485  0.088  0.232  1.0
  O  O33  1  0.515  0.588  0.768  1.0
  O  O34  1  0.015  0.088  0.732  1.0
  O  O35  1  0.985  0.588  0.268  1.0
  O  O36  1  0.485  0.412  0.232  1.0
  O  O37  1  0.515  0.912  0.768  1.0
  O  O38  1  0.015  0.412  0.732  1.0
  O  O39  1  0.985  0.912  0.268  1.0
  O  O40  1  0.068  0.250  0.155  1.0
  O  O41  1  0.932  0.750  0.845  1.0
  O  O42  1  0.432  0.250  0.655  1.0
  O  O43  1  0.568  0.750  0.345  1.0
[/CIF]
.
The structure described by Gd2Si2O7 crystallizes in the orthorhombic Pnma space group. Gd(1) is bonded to one O(1), one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form distorted GdO7 pentagonal bipyramids that share corners with three equivalent Gd(1)O7 pentagonal bipyramids, corners with two equivalent Si(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Gd(1)O7 pentagonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with four equivalent Gd(1)O7 pentagonal bipyramids,  a cornercorner with one Si(2)O4 tetrahedra, and edges with two equivalent Gd(1)O7 pentagonal bipyramids. In the second Si site, Si(2) is bonded to one O(3), one O(5), and two equivalent O(4) atoms to form SiO4 tetrahedra that share corners with four equivalent Gd(1)O7 pentagonal bipyramids,  a cornercorner with one Si(1)O4 tetrahedra, and edges with two equivalent Gd(1)O7 pentagonal bipyramids. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Gd(1) and one Si(2) atom. In the second O site, O(5) is bonded in a trigonal planar geometry to two equivalent Gd(1) and one Si(2) atom. In the third O site, O(1) is bonded in a trigonal planar geometry to two equivalent Gd(1) and one Si(1) atom. In the fourth O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Gd(1) and one Si(1) atom. In the fifth O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Gd(1), one Si(1), and one Si(2) atom. is represented by the CIF card [CIF]
data_Gd2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.067
_cell_length_b   8.289
_cell_length_c   13.871
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   582.490
_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
  Gd  Gd0  1  0.839  0.008  0.125  1.0
  Gd  Gd1  1  0.161  0.508  0.875  1.0
  Gd  Gd2  1  0.661  0.008  0.625  1.0
  Gd  Gd3  1  0.339  0.508  0.375  1.0
  Gd  Gd4  1  0.839  0.492  0.125  1.0
  Gd  Gd5  1  0.161  0.992  0.875  1.0
  Gd  Gd6  1  0.661  0.492  0.625  1.0
  Gd  Gd7  1  0.339  0.992  0.375  1.0
  Si  Si8  1  0.123  0.750  0.539  1.0
  Si  Si9  1  0.877  0.250  0.461  1.0
  Si  Si10  1  0.377  0.750  0.039  1.0
  Si  Si11  1  0.623  0.250  0.961  1.0
  Si  Si12  1  0.878  0.750  0.320  1.0
  Si  Si13  1  0.122  0.250  0.680  1.0
  Si  Si14  1  0.622  0.750  0.820  1.0
  Si  Si15  1  0.378  0.250  0.180  1.0
  O  O16  1  0.850  0.750  0.599  1.0
  O  O17  1  0.150  0.250  0.401  1.0
  O  O18  1  0.650  0.750  0.099  1.0
  O  O19  1  0.350  0.250  0.901  1.0
  O  O20  1  0.289  0.916  0.547  1.0
  O  O21  1  0.711  0.416  0.453  1.0
  O  O22  1  0.211  0.916  0.047  1.0
  O  O23  1  0.789  0.416  0.953  1.0
  O  O24  1  0.289  0.584  0.547  1.0
  O  O25  1  0.711  0.084  0.453  1.0
  O  O26  1  0.211  0.584  0.047  1.0
  O  O27  1  0.789  0.084  0.953  1.0
  O  O28  1  0.059  0.750  0.420  1.0
  O  O29  1  0.941  0.250  0.580  1.0
  O  O30  1  0.441  0.750  0.920  1.0
  O  O31  1  0.559  0.250  0.080  1.0
  O  O32  1  0.485  0.088  0.232  1.0
  O  O33  1  0.515  0.588  0.768  1.0
  O  O34  1  0.015  0.088  0.732  1.0
  O  O35  1  0.985  0.588  0.268  1.0
  O  O36  1  0.485  0.412  0.232  1.0
  O  O37  1  0.515  0.912  0.768  1.0
  O  O38  1  0.015  0.412  0.732  1.0
  O  O39  1  0.985  0.912  0.268  1.0
  O  O40  1  0.068  0.250  0.155  1.0
  O  O41  1  0.932  0.750  0.845  1.0
  O  O42  1  0.432  0.250  0.655  1.0
  O  O43  1  0.568  0.750  0.345  1.0
[/CIF]
.