The crystal structure described by Ba7Ca2Cr2Mn3O20 crystallizes in the trigonal R-3m space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one O(4), three equivalent O(1), and six equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Mn(1)O6 octahedra, faces with three equivalent Ba(2)O12 cuboctahedra,  a faceface with one Ca(1)O6 octahedra, faces with three equivalent Mn(1)O6 octahedra, and faces with three equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. In the fourth Ba site, Ba(4) is bonded to six equivalent O(3) atoms to form distorted BaO6 cuboctahedra that share corners with six equivalent Cr(1)O4 tetrahedra and faces with two equivalent Ca(1)O6 octahedra. Ca(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form CaO6 octahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Cr(1)O4 tetrahedra,  a faceface with one Ba(2)O12 cuboctahedra, and  a faceface with one Ba(4)O6 cuboctahedra. The corner-sharing octahedra are not tilted. Cr(1) is bonded to one O(4) and three equivalent O(3) atoms to form CrO4 tetrahedra that share corners with three equivalent Ba(4)O6 cuboctahedra and corners with three equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Ca(1)O6 octahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and  a faceface with one Mn(2)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mn site, Mn(2) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share faces with six equivalent Ba(2)O12 cuboctahedra and faces with two equivalent Mn(1)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Ca(1), and one Mn(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(3), three equivalent Ba(2), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(4), two equivalent Ba(1), one Ca(1), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Ba(1) and one Cr(1) atom. is represented by the CIF card [CIF]
data_Ba7Ca2Mn3Cr2O20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   17.692
_cell_length_b   17.692
_cell_length_c   17.692
_cell_angle_alpha   19.190
_cell_angle_beta   19.190
_cell_angle_gamma   19.190
_symmetry_Int_Tables_number   1
_cell_volume   523.026
_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
  Ba  Ba0  1  0.612  0.612  0.612  1.0
  Ba  Ba1  1  0.146  0.146  0.146  1.0
  Ba  Ba2  1  0.388  0.388  0.388  1.0
  Ba  Ba3  1  0.226  0.226  0.226  1.0
  Ba  Ba4  1  0.774  0.774  0.774  1.0
  Ba  Ba5  1  0.854  0.854  0.854  1.0
  Ba  Ba6  1  0.000  0.000  0.000  1.0
  Ca  Ca7  1  0.925  0.925  0.925  1.0
  Ca  Ca8  1  0.075  0.075  0.075  1.0
  Mn  Mn9  1  0.549  0.549  0.549  1.0
  Mn  Mn10  1  0.451  0.451  0.451  1.0
  Mn  Mn11  1  0.500  0.500  0.500  1.0
  Cr  Cr12  1  0.697  0.697  0.697  1.0
  Cr  Cr13  1  0.303  0.303  0.303  1.0
  O  O14  1  0.278  0.278  0.736  1.0
  O  O15  1  0.815  0.377  0.377  1.0
  O  O16  1  0.868  0.392  0.868  1.0
  O  O17  1  0.665  0.665  0.665  1.0
  O  O18  1  0.335  0.335  0.335  1.0
  O  O19  1  0.377  0.815  0.377  1.0
  O  O20  1  0.132  0.132  0.608  1.0
  O  O21  1  0.868  0.868  0.392  1.0
  O  O22  1  0.722  0.264  0.722  1.0
  O  O23  1  0.264  0.722  0.722  1.0
  O  O24  1  0.278  0.736  0.278  1.0
  O  O25  1  0.392  0.868  0.868  1.0
  O  O26  1  0.722  0.722  0.264  1.0
  O  O27  1  0.623  0.185  0.623  1.0
  O  O28  1  0.185  0.623  0.623  1.0
  O  O29  1  0.132  0.608  0.132  1.0
  O  O30  1  0.608  0.132  0.132  1.0
  O  O31  1  0.623  0.623  0.185  1.0
  O  O32  1  0.377  0.377  0.815  1.0
  O  O33  1  0.736  0.278  0.278  1.0
[/CIF]
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The crystal structure described by Ba7Ca2Cr2Mn3O20 crystallizes in the trigonal R-3m space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to one O(4), three equivalent O(1), and six equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form distorted BaO12 cuboctahedra that share corners with six equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Mn(1)O6 octahedra, faces with three equivalent Ba(2)O12 cuboctahedra,  a faceface with one Ca(1)O6 octahedra, faces with three equivalent Mn(1)O6 octahedra, and faces with three equivalent Mn(2)O6 octahedra. The corner-sharing octahedral tilt angles are 8°. In the third Ba site, Ba(3) is bonded in a 9-coordinate geometry to three equivalent O(2) and six equivalent O(1) atoms. In the fourth Ba site, Ba(4) is bonded to six equivalent O(3) atoms to form distorted BaO6 cuboctahedra that share corners with six equivalent Cr(1)O4 tetrahedra and faces with two equivalent Ca(1)O6 octahedra. Ca(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form CaO6 octahedra that share corners with three equivalent Mn(1)O6 octahedra, corners with three equivalent Cr(1)O4 tetrahedra,  a faceface with one Ba(2)O12 cuboctahedra, and  a faceface with one Ba(4)O6 cuboctahedra. The corner-sharing octahedra are not tilted. Cr(1) is bonded to one O(4) and three equivalent O(3) atoms to form CrO4 tetrahedra that share corners with three equivalent Ba(4)O6 cuboctahedra and corners with three equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles are 23°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form MnO6 octahedra that share corners with three equivalent Ba(2)O12 cuboctahedra, corners with three equivalent Ca(1)O6 octahedra, faces with three equivalent Ba(2)O12 cuboctahedra, and  a faceface with one Mn(2)O6 octahedra. The corner-sharing octahedra are not tilted. In the second Mn site, Mn(2) is bonded to six equivalent O(2) atoms to form MnO6 octahedra that share faces with six equivalent Ba(2)O12 cuboctahedra and faces with two equivalent Mn(1)O6 octahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), two equivalent Ba(3), one Ca(1), and one Mn(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Ba(3), three equivalent Ba(2), one Mn(1), and one Mn(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Ba(4), two equivalent Ba(1), one Ca(1), and one Cr(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Ba(1) and one Cr(1) atom. is represented by the CIF card [CIF]
data_Ba7Ca2Mn3Cr2O20
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   17.692
_cell_length_b   17.692
_cell_length_c   17.692
_cell_angle_alpha   19.190
_cell_angle_beta   19.190
_cell_angle_gamma   19.190
_symmetry_Int_Tables_number   1
_cell_volume   523.026
_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
  Ba  Ba0  1  0.612  0.612  0.612  1.0
  Ba  Ba1  1  0.146  0.146  0.146  1.0
  Ba  Ba2  1  0.388  0.388  0.388  1.0
  Ba  Ba3  1  0.226  0.226  0.226  1.0
  Ba  Ba4  1  0.774  0.774  0.774  1.0
  Ba  Ba5  1  0.854  0.854  0.854  1.0
  Ba  Ba6  1  0.000  0.000  0.000  1.0
  Ca  Ca7  1  0.925  0.925  0.925  1.0
  Ca  Ca8  1  0.075  0.075  0.075  1.0
  Mn  Mn9  1  0.549  0.549  0.549  1.0
  Mn  Mn10  1  0.451  0.451  0.451  1.0
  Mn  Mn11  1  0.500  0.500  0.500  1.0
  Cr  Cr12  1  0.697  0.697  0.697  1.0
  Cr  Cr13  1  0.303  0.303  0.303  1.0
  O  O14  1  0.278  0.278  0.736  1.0
  O  O15  1  0.815  0.377  0.377  1.0
  O  O16  1  0.868  0.392  0.868  1.0
  O  O17  1  0.665  0.665  0.665  1.0
  O  O18  1  0.335  0.335  0.335  1.0
  O  O19  1  0.377  0.815  0.377  1.0
  O  O20  1  0.132  0.132  0.608  1.0
  O  O21  1  0.868  0.868  0.392  1.0
  O  O22  1  0.722  0.264  0.722  1.0
  O  O23  1  0.264  0.722  0.722  1.0
  O  O24  1  0.278  0.736  0.278  1.0
  O  O25  1  0.392  0.868  0.868  1.0
  O  O26  1  0.722  0.722  0.264  1.0
  O  O27  1  0.623  0.185  0.623  1.0
  O  O28  1  0.185  0.623  0.623  1.0
  O  O29  1  0.132  0.608  0.132  1.0
  O  O30  1  0.608  0.132  0.132  1.0
  O  O31  1  0.623  0.623  0.185  1.0
  O  O32  1  0.377  0.377  0.815  1.0
  O  O33  1  0.736  0.278  0.278  1.0
[/CIF]
.