The material structure described by Sm2O3 crystallizes in the trigonal P-3m1 space group. Sm(1) is bonded in a 7-coordinate geometry to three equivalent O(2) and four equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sm(1) atoms to form OSm4 tetrahedra that share corners with six equivalent O(2)Sm6 octahedra, corners with six equivalent O(1)Sm4 tetrahedra, edges with three equivalent O(2)Sm6 octahedra, and edges with three equivalent O(1)Sm4 tetrahedra. The corner-sharing octahedral tilt angles range from 18-56°. In the second O site, O(2) is bonded to six equivalent Sm(1) atoms to form OSm6 octahedra that share corners with twelve equivalent O(1)Sm4 tetrahedra, edges with six equivalent O(2)Sm6 octahedra, and edges with six equivalent O(1)Sm4 tetrahedra. is represented by the CIF file [CIF]
data_Sm2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.779
_cell_length_b   3.779
_cell_length_c   5.942
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   73.481
_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
  Sm  Sm0  1  0.667  0.333  0.752  1.0
  Sm  Sm1  1  0.333  0.667  0.248  1.0
  O  O2  1  0.667  0.333  0.355  1.0
  O  O3  1  0.333  0.667  0.645  1.0
  O  O4  1  0.000  0.000  0.000  1.0
[/CIF]
.
The material structure described by Sm2O3 crystallizes in the trigonal P-3m1 space group. Sm(1) is bonded in a 7-coordinate geometry to three equivalent O(2) and four equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Sm(1) atoms to form OSm4 tetrahedra that share corners with six equivalent O(2)Sm6 octahedra, corners with six equivalent O(1)Sm4 tetrahedra, edges with three equivalent O(2)Sm6 octahedra, and edges with three equivalent O(1)Sm4 tetrahedra. The corner-sharing octahedral tilt angles range from 18-56°. In the second O site, O(2) is bonded to six equivalent Sm(1) atoms to form OSm6 octahedra that share corners with twelve equivalent O(1)Sm4 tetrahedra, edges with six equivalent O(2)Sm6 octahedra, and edges with six equivalent O(1)Sm4 tetrahedra. is represented by the CIF file [CIF]
data_Sm2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.779
_cell_length_b   3.779
_cell_length_c   5.942
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   73.481
_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
  Sm  Sm0  1  0.667  0.333  0.752  1.0
  Sm  Sm1  1  0.333  0.667  0.248  1.0
  O  O2  1  0.667  0.333  0.355  1.0
  O  O3  1  0.333  0.667  0.645  1.0
  O  O4  1  0.000  0.000  0.000  1.0
[/CIF]
.