The crystal structure described by Ca3Sn2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), and three equivalent O(1) atoms. Sn(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing SnO6 octahedra. The corner-sharing octahedral tilt angles range from 33-34°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ca(2) and one Sn(1) atom to form OCa3Sn tetrahedra that share  a cornercorner with one O(4)Ca2Sn2 tetrahedra and corners with six equivalent O(1)Ca3Sn tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ca(1), two equivalent Ca(2), and two equivalent Sn(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(2), two equivalent Ca(1), and two equivalent Sn(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Sn(1) atoms to form distorted OCa2Sn2 tetrahedra that share corners with two equivalent O(4)Ca2Sn2 tetrahedra and corners with two equivalent O(1)Ca3Sn tetrahedra. is represented by the CIF card [CIF]
data_Ca3Sn2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.357
_cell_length_b   10.357
_cell_length_c   5.785
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   148.354
_symmetry_Int_Tables_number   1
_cell_volume   325.550
_cell_formula_units_Z   2
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
  Ca  Ca0  1  0.240  0.240  0.302  1.0
  Ca  Ca1  1  0.760  0.760  0.802  1.0
  Ca  Ca2  1  0.044  0.427  0.195  1.0
  Ca  Ca3  1  0.956  0.573  0.695  1.0
  Ca  Ca4  1  0.427  0.044  0.195  1.0
  Ca  Ca5  1  0.573  0.956  0.695  1.0
  Sn  Sn6  1  0.849  0.648  0.250  1.0
  Sn  Sn7  1  0.151  0.352  0.750  1.0
  Sn  Sn8  1  0.352  0.151  0.750  1.0
  Sn  Sn9  1  0.648  0.849  0.250  1.0
  O  O10  1  0.636  0.037  0.289  1.0
  O  O11  1  0.364  0.963  0.789  1.0
  O  O12  1  0.963  0.364  0.789  1.0
  O  O13  1  0.037  0.636  0.289  1.0
  O  O14  1  0.437  0.677  0.947  1.0
  O  O15  1  0.563  0.323  0.447  1.0
  O  O16  1  0.323  0.563  0.447  1.0
  O  O17  1  0.677  0.437  0.947  1.0
  O  O18  1  0.978  0.136  0.055  1.0
  O  O19  1  0.022  0.864  0.555  1.0
  O  O20  1  0.648  0.648  0.208  1.0
  O  O21  1  0.352  0.352  0.708  1.0
  O  O22  1  0.136  0.978  0.055  1.0
  O  O23  1  0.864  0.022  0.555  1.0
[/CIF]
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The crystal structure described by Ca3Sn2O7 crystallizes in the orthorhombic Cmc2_1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(3), two equivalent O(2), and three equivalent O(1) atoms. Sn(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms to form corner-sharing SnO6 octahedra. The corner-sharing octahedral tilt angles range from 33-34°. There are four inequivalent O sites. In the first O site, O(1) is bonded to three equivalent Ca(2) and one Sn(1) atom to form OCa3Sn tetrahedra that share  a cornercorner with one O(4)Ca2Sn2 tetrahedra and corners with six equivalent O(1)Ca3Sn tetrahedra. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Ca(1), two equivalent Ca(2), and two equivalent Sn(1) atoms. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ca(2), two equivalent Ca(1), and two equivalent Sn(1) atoms. In the fourth O site, O(4) is bonded to two equivalent Ca(1) and two equivalent Sn(1) atoms to form distorted OCa2Sn2 tetrahedra that share corners with two equivalent O(4)Ca2Sn2 tetrahedra and corners with two equivalent O(1)Ca3Sn tetrahedra. is represented by the CIF card [CIF]
data_Ca3Sn2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.357
_cell_length_b   10.357
_cell_length_c   5.785
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   148.354
_symmetry_Int_Tables_number   1
_cell_volume   325.550
_cell_formula_units_Z   2
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
  Ca  Ca0  1  0.240  0.240  0.302  1.0
  Ca  Ca1  1  0.760  0.760  0.802  1.0
  Ca  Ca2  1  0.044  0.427  0.195  1.0
  Ca  Ca3  1  0.956  0.573  0.695  1.0
  Ca  Ca4  1  0.427  0.044  0.195  1.0
  Ca  Ca5  1  0.573  0.956  0.695  1.0
  Sn  Sn6  1  0.849  0.648  0.250  1.0
  Sn  Sn7  1  0.151  0.352  0.750  1.0
  Sn  Sn8  1  0.352  0.151  0.750  1.0
  Sn  Sn9  1  0.648  0.849  0.250  1.0
  O  O10  1  0.636  0.037  0.289  1.0
  O  O11  1  0.364  0.963  0.789  1.0
  O  O12  1  0.963  0.364  0.789  1.0
  O  O13  1  0.037  0.636  0.289  1.0
  O  O14  1  0.437  0.677  0.947  1.0
  O  O15  1  0.563  0.323  0.447  1.0
  O  O16  1  0.323  0.563  0.447  1.0
  O  O17  1  0.677  0.437  0.947  1.0
  O  O18  1  0.978  0.136  0.055  1.0
  O  O19  1  0.022  0.864  0.555  1.0
  O  O20  1  0.648  0.648  0.208  1.0
  O  O21  1  0.352  0.352  0.708  1.0
  O  O22  1  0.136  0.978  0.055  1.0
  O  O23  1  0.864  0.022  0.555  1.0
[/CIF]
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