The compound described by Cr2O3 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedra are not tilted. In the second Cr site, Cr(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Cr(2) and four equivalent Cr(1) atoms to form OCr6 octahedra that share corners with four equivalent O(3)Cr5 square pyramids, edges with two equivalent O(1)Cr6 octahedra, and edges with six equivalent O(3)Cr5 square pyramids. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one Cr(1) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded to two equivalent Cr(2) and three equivalent Cr(1) atoms to form OCr5 square pyramids that share corners with two equivalent O(1)Cr6 octahedra, edges with three equivalent O(1)Cr6 octahedra, and edges with four equivalent O(3)Cr5 square pyramids. The corner-sharing octahedral tilt angles are 7°. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Cr(2) atoms. is represented by the CIF card [CIF]
data_Cr2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.170
_cell_length_b   5.170
_cell_length_c   15.627
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   146.183
_symmetry_Int_Tables_number   1
_cell_volume   232.476
_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
  Cr  Cr0  1  0.634  0.366  0.044  1.0
  Cr  Cr1  1  0.366  0.634  0.956  1.0
  Cr  Cr2  1  0.634  0.366  0.456  1.0
  Cr  Cr3  1  0.366  0.634  0.544  1.0
  Cr  Cr4  1  0.095  0.905  0.644  1.0
  Cr  Cr5  1  0.905  0.095  0.356  1.0
  Cr  Cr6  1  0.905  0.095  0.144  1.0
  Cr  Cr7  1  0.095  0.905  0.856  1.0
  O  O8  1  0.000  0.000  0.500  1.0
  O  O9  1  0.000  0.000  0.000  1.0
  O  O10  1  0.472  0.528  0.852  1.0
  O  O11  1  0.528  0.472  0.148  1.0
  O  O12  1  0.528  0.472  0.352  1.0
  O  O13  1  0.472  0.528  0.648  1.0
  O  O14  1  0.735  0.265  0.927  1.0
  O  O15  1  0.265  0.735  0.073  1.0
  O  O16  1  0.265  0.735  0.427  1.0
  O  O17  1  0.735  0.265  0.573  1.0
  O  O18  1  0.172  0.828  0.750  1.0
  O  O19  1  0.828  0.172  0.250  1.0
[/CIF]
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The compound described by Cr2O3 crystallizes in the orthorhombic Cmcm space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), two equivalent O(1), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing CrO6 octahedra. The corner-sharing octahedra are not tilted. In the second Cr site, Cr(2) is bonded in a 6-coordinate geometry to one O(1), one O(4), two equivalent O(2), and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Cr(2) and four equivalent Cr(1) atoms to form OCr6 octahedra that share corners with four equivalent O(3)Cr5 square pyramids, edges with two equivalent O(1)Cr6 octahedra, and edges with six equivalent O(3)Cr5 square pyramids. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to one Cr(1) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded to two equivalent Cr(2) and three equivalent Cr(1) atoms to form OCr5 square pyramids that share corners with two equivalent O(1)Cr6 octahedra, edges with three equivalent O(1)Cr6 octahedra, and edges with four equivalent O(3)Cr5 square pyramids. The corner-sharing octahedral tilt angles are 7°. In the fourth O site, O(4) is bonded in a bent 120 degrees geometry to two equivalent Cr(2) atoms. is represented by the CIF card [CIF]
data_Cr2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.170
_cell_length_b   5.170
_cell_length_c   15.627
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   146.183
_symmetry_Int_Tables_number   1
_cell_volume   232.476
_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
  Cr  Cr0  1  0.634  0.366  0.044  1.0
  Cr  Cr1  1  0.366  0.634  0.956  1.0
  Cr  Cr2  1  0.634  0.366  0.456  1.0
  Cr  Cr3  1  0.366  0.634  0.544  1.0
  Cr  Cr4  1  0.095  0.905  0.644  1.0
  Cr  Cr5  1  0.905  0.095  0.356  1.0
  Cr  Cr6  1  0.905  0.095  0.144  1.0
  Cr  Cr7  1  0.095  0.905  0.856  1.0
  O  O8  1  0.000  0.000  0.500  1.0
  O  O9  1  0.000  0.000  0.000  1.0
  O  O10  1  0.472  0.528  0.852  1.0
  O  O11  1  0.528  0.472  0.148  1.0
  O  O12  1  0.528  0.472  0.352  1.0
  O  O13  1  0.472  0.528  0.648  1.0
  O  O14  1  0.735  0.265  0.927  1.0
  O  O15  1  0.265  0.735  0.073  1.0
  O  O16  1  0.265  0.735  0.427  1.0
  O  O17  1  0.735  0.265  0.573  1.0
  O  O18  1  0.172  0.828  0.750  1.0
  O  O19  1  0.828  0.172  0.250  1.0
[/CIF]
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