The compound described by Ca3Mn2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ca(1)O12 cuboctahedra, and faces with eight equivalent Mn(1)O6 octahedra. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to four equivalent O(3) and five equivalent O(2) atoms. Mn(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form MnO6 octahedra that share corners with five equivalent Mn(1)O6 octahedra and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Mn(1) atoms to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca4Mn2 octahedra, corners with sixteen equivalent O(3)Ca4Mn2 octahedra, edges with four equivalent O(1)Ca4Mn2 octahedra, and faces with eight equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded to five equivalent Ca(2) and one Mn(1) atom to form distorted OCa5Mn octahedra that share  a cornercorner with one O(1)Ca4Mn2 octahedra, corners with four equivalent O(2)Ca5Mn octahedra, corners with twelve equivalent O(3)Ca4Mn2 octahedra, edges with eight equivalent O(2)Ca5Mn octahedra, and faces with four equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-53°. In the third O site, O(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Mn(1) atoms to form distorted OCa4Mn2 octahedra that share corners with four equivalent O(1)Ca4Mn2 octahedra, corners with six equivalent O(2)Ca5Mn octahedra, corners with eight equivalent O(3)Ca4Mn2 octahedra, edges with three equivalent O(3)Ca4Mn2 octahedra, faces with two equivalent O(1)Ca4Mn2 octahedra, faces with two equivalent O(2)Ca5Mn octahedra, and faces with four equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the fourth O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Mn(1) atoms to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca4Mn2 octahedra, corners with sixteen equivalent O(3)Ca4Mn2 octahedra, edges with four equivalent O(1)Ca4Mn2 octahedra, and faces with eight equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the CIF file [CIF]
data_Ca3Mn2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.786
_cell_length_b   3.786
_cell_length_c   10.047
_cell_angle_alpha   100.861
_cell_angle_beta   100.861
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   138.806
_cell_formula_units_Z   1
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  0.500  0.500  0.000  1.0
  Ca  Ca1  1  0.684  0.684  0.367  1.0
  Ca  Ca2  1  0.316  0.316  0.633  1.0
  Mn  Mn3  1  0.900  0.900  0.800  1.0
  Mn  Mn4  1  0.100  0.100  0.200  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.802  0.802  0.604  1.0
  O  O7  1  0.198  0.198  0.396  1.0
  O  O8  1  0.402  0.902  0.804  1.0
  O  O9  1  0.902  0.402  0.804  1.0
  O  O10  1  0.598  0.098  0.196  1.0
  O  O11  1  0.098  0.598  0.196  1.0
[/CIF]
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The compound described by Ca3Mn2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to four equivalent O(1) and eight equivalent O(3) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ca(1)O12 cuboctahedra, and faces with eight equivalent Mn(1)O6 octahedra. In the second Ca site, Ca(2) is bonded in a 9-coordinate geometry to four equivalent O(3) and five equivalent O(2) atoms. Mn(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form MnO6 octahedra that share corners with five equivalent Mn(1)O6 octahedra and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-3°. There are four inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Mn(1) atoms to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca4Mn2 octahedra, corners with sixteen equivalent O(3)Ca4Mn2 octahedra, edges with four equivalent O(1)Ca4Mn2 octahedra, and faces with eight equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second O site, O(2) is bonded to five equivalent Ca(2) and one Mn(1) atom to form distorted OCa5Mn octahedra that share  a cornercorner with one O(1)Ca4Mn2 octahedra, corners with four equivalent O(2)Ca5Mn octahedra, corners with twelve equivalent O(3)Ca4Mn2 octahedra, edges with eight equivalent O(2)Ca5Mn octahedra, and faces with four equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-53°. In the third O site, O(3) is bonded to two equivalent Ca(1), two equivalent Ca(2), and two equivalent Mn(1) atoms to form distorted OCa4Mn2 octahedra that share corners with four equivalent O(1)Ca4Mn2 octahedra, corners with six equivalent O(2)Ca5Mn octahedra, corners with eight equivalent O(3)Ca4Mn2 octahedra, edges with three equivalent O(3)Ca4Mn2 octahedra, faces with two equivalent O(1)Ca4Mn2 octahedra, faces with two equivalent O(2)Ca5Mn octahedra, and faces with four equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the fourth O site, O(1) is bonded to four equivalent Ca(1) and two equivalent Mn(1) atoms to form distorted OCa4Mn2 octahedra that share corners with two equivalent O(2)Ca5Mn octahedra, corners with four equivalent O(1)Ca4Mn2 octahedra, corners with sixteen equivalent O(3)Ca4Mn2 octahedra, edges with four equivalent O(1)Ca4Mn2 octahedra, and faces with eight equivalent O(3)Ca4Mn2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the CIF file [CIF]
data_Ca3Mn2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.786
_cell_length_b   3.786
_cell_length_c   10.047
_cell_angle_alpha   100.861
_cell_angle_beta   100.861
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   138.806
_cell_formula_units_Z   1
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  0.500  0.500  0.000  1.0
  Ca  Ca1  1  0.684  0.684  0.367  1.0
  Ca  Ca2  1  0.316  0.316  0.633  1.0
  Mn  Mn3  1  0.900  0.900  0.800  1.0
  Mn  Mn4  1  0.100  0.100  0.200  1.0
  O  O5  1  0.000  0.000  0.000  1.0
  O  O6  1  0.802  0.802  0.604  1.0
  O  O7  1  0.198  0.198  0.396  1.0
  O  O8  1  0.402  0.902  0.804  1.0
  O  O9  1  0.902  0.402  0.804  1.0
  O  O10  1  0.598  0.098  0.196  1.0
  O  O11  1  0.098  0.598  0.196  1.0
[/CIF]
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