The structure described by Eu2O3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), two equivalent O(2), and three equivalent O(5) atoms. In the second Eu site, Eu(2) is bonded in a 7-coordinate geometry to two equivalent O(2), two equivalent O(4), and three equivalent O(1) atoms. In the third Eu site, Eu(3) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing EuO6 octahedra. The corner-sharing octahedra are not tilted. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1) and three equivalent Eu(2) atoms to form distorted OEu4 trigonal pyramids that share  a cornercorner with one O(3)Eu6 octahedra, corners with two equivalent O(2)Eu5 square pyramids, corners with three equivalent O(5)Eu4 tetrahedra, corners with six equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(1)Eu4 trigonal pyramids, edges with three equivalent O(2)Eu5 square pyramids, and edges with two equivalent O(1)Eu4 trigonal pyramids. The corner-sharing octahedral tilt angles are 37°. In the second O site, O(2) is bonded to one Eu(3), two equivalent Eu(1), and two equivalent Eu(2) atoms to form distorted OEu5 square pyramids that share corners with two equivalent O(4)Eu4 tetrahedra, corners with five equivalent O(5)Eu4 tetrahedra, corners with two equivalent O(1)Eu4 trigonal pyramids, edges with two equivalent O(3)Eu6 octahedra, edges with two equivalent O(2)Eu5 square pyramids,  an edgeedge with one O(5)Eu4 tetrahedra, edges with two equivalent O(4)Eu4 tetrahedra, and edges with three equivalent O(1)Eu4 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Eu(1) and four equivalent Eu(3) atoms to form OEu6 octahedra that share corners with two equivalent O(5)Eu4 tetrahedra, corners with four equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(1)Eu4 trigonal pyramids, edges with two equivalent O(3)Eu6 octahedra, edges with four equivalent O(2)Eu5 square pyramids, edges with two equivalent O(4)Eu4 tetrahedra, and edges with four equivalent O(5)Eu4 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Eu(2) and two equivalent Eu(3) atoms to form OEu4 tetrahedra that share corners with two equivalent O(3)Eu6 octahedra, corners with two equivalent O(2)Eu5 square pyramids, corners with two equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(5)Eu4 tetrahedra, corners with six equivalent O(1)Eu4 trigonal pyramids,  an edgeedge with one O(3)Eu6 octahedra, edges with two equivalent O(2)Eu5 square pyramids, and  an edgeedge with one O(4)Eu4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the fifth O site, O(5) is bonded to one Eu(3) and three equivalent Eu(1) atoms to form OEu4 tetrahedra that share  a cornercorner with one O(3)Eu6 octahedra, corners with five equivalent O(2)Eu5 square pyramids, corners with two equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(5)Eu4 tetrahedra, corners with three equivalent O(1)Eu4 trigonal pyramids, edges with two equivalent O(3)Eu6 octahedra,  an edgeedge with one O(2)Eu5 square pyramid, and edges with two equivalent O(5)Eu4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. is represented by the CIF card [CIF]
data_Eu2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.631
_cell_length_b   7.314
_cell_length_c   8.842
_cell_angle_alpha   99.738
_cell_angle_beta   90.000
_cell_angle_gamma   104.374
_symmetry_Int_Tables_number   1
_cell_volume   223.974
_cell_formula_units_Z   3
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
  Eu  Eu0  1  0.310  0.620  0.863  1.0
  Eu  Eu1  1  0.364  0.728  0.511  1.0
  Eu  Eu2  1  0.032  0.063  0.815  1.0
  Eu  Eu3  1  0.690  0.380  0.137  1.0
  Eu  Eu4  1  0.968  0.937  0.185  1.0
  Eu  Eu5  1  0.636  0.272  0.489  1.0
  O  O6  1  0.791  0.581  0.375  1.0
  O  O7  1  0.209  0.419  0.625  1.0
  O  O8  1  0.875  0.750  0.713  1.0
  O  O9  1  0.500  0.000  0.000  1.0
  O  O10  1  0.529  0.057  0.658  1.0
  O  O11  1  0.471  0.943  0.342  1.0
  O  O12  1  0.125  0.250  0.287  1.0
  O  O13  1  0.827  0.653  0.031  1.0
  O  O14  1  0.173  0.347  0.969  1.0
[/CIF]
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The structure described by Eu2O3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 7-coordinate geometry to one O(1), one O(3), two equivalent O(2), and three equivalent O(5) atoms. In the second Eu site, Eu(2) is bonded in a 7-coordinate geometry to two equivalent O(2), two equivalent O(4), and three equivalent O(1) atoms. In the third Eu site, Eu(3) is bonded to one O(2), one O(5), two equivalent O(3), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing EuO6 octahedra. The corner-sharing octahedra are not tilted. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1) and three equivalent Eu(2) atoms to form distorted OEu4 trigonal pyramids that share  a cornercorner with one O(3)Eu6 octahedra, corners with two equivalent O(2)Eu5 square pyramids, corners with three equivalent O(5)Eu4 tetrahedra, corners with six equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(1)Eu4 trigonal pyramids, edges with three equivalent O(2)Eu5 square pyramids, and edges with two equivalent O(1)Eu4 trigonal pyramids. The corner-sharing octahedral tilt angles are 37°. In the second O site, O(2) is bonded to one Eu(3), two equivalent Eu(1), and two equivalent Eu(2) atoms to form distorted OEu5 square pyramids that share corners with two equivalent O(4)Eu4 tetrahedra, corners with five equivalent O(5)Eu4 tetrahedra, corners with two equivalent O(1)Eu4 trigonal pyramids, edges with two equivalent O(3)Eu6 octahedra, edges with two equivalent O(2)Eu5 square pyramids,  an edgeedge with one O(5)Eu4 tetrahedra, edges with two equivalent O(4)Eu4 tetrahedra, and edges with three equivalent O(1)Eu4 trigonal pyramids. In the third O site, O(3) is bonded to two equivalent Eu(1) and four equivalent Eu(3) atoms to form OEu6 octahedra that share corners with two equivalent O(5)Eu4 tetrahedra, corners with four equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(1)Eu4 trigonal pyramids, edges with two equivalent O(3)Eu6 octahedra, edges with four equivalent O(2)Eu5 square pyramids, edges with two equivalent O(4)Eu4 tetrahedra, and edges with four equivalent O(5)Eu4 tetrahedra. In the fourth O site, O(4) is bonded to two equivalent Eu(2) and two equivalent Eu(3) atoms to form OEu4 tetrahedra that share corners with two equivalent O(3)Eu6 octahedra, corners with two equivalent O(2)Eu5 square pyramids, corners with two equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(5)Eu4 tetrahedra, corners with six equivalent O(1)Eu4 trigonal pyramids,  an edgeedge with one O(3)Eu6 octahedra, edges with two equivalent O(2)Eu5 square pyramids, and  an edgeedge with one O(4)Eu4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. In the fifth O site, O(5) is bonded to one Eu(3) and three equivalent Eu(1) atoms to form OEu4 tetrahedra that share  a cornercorner with one O(3)Eu6 octahedra, corners with five equivalent O(2)Eu5 square pyramids, corners with two equivalent O(4)Eu4 tetrahedra, corners with two equivalent O(5)Eu4 tetrahedra, corners with three equivalent O(1)Eu4 trigonal pyramids, edges with two equivalent O(3)Eu6 octahedra,  an edgeedge with one O(2)Eu5 square pyramid, and edges with two equivalent O(5)Eu4 tetrahedra. The corner-sharing octahedral tilt angles are 50°. is represented by the CIF card [CIF]
data_Eu2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.631
_cell_length_b   7.314
_cell_length_c   8.842
_cell_angle_alpha   99.738
_cell_angle_beta   90.000
_cell_angle_gamma   104.374
_symmetry_Int_Tables_number   1
_cell_volume   223.974
_cell_formula_units_Z   3
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
  Eu  Eu0  1  0.310  0.620  0.863  1.0
  Eu  Eu1  1  0.364  0.728  0.511  1.0
  Eu  Eu2  1  0.032  0.063  0.815  1.0
  Eu  Eu3  1  0.690  0.380  0.137  1.0
  Eu  Eu4  1  0.968  0.937  0.185  1.0
  Eu  Eu5  1  0.636  0.272  0.489  1.0
  O  O6  1  0.791  0.581  0.375  1.0
  O  O7  1  0.209  0.419  0.625  1.0
  O  O8  1  0.875  0.750  0.713  1.0
  O  O9  1  0.500  0.000  0.000  1.0
  O  O10  1  0.529  0.057  0.658  1.0
  O  O11  1  0.471  0.943  0.342  1.0
  O  O12  1  0.125  0.250  0.287  1.0
  O  O13  1  0.827  0.653  0.031  1.0
  O  O14  1  0.173  0.347  0.969  1.0
[/CIF]
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