The compound described by Er2O3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing ErO6 octahedra. The corner-sharing octahedra are not tilted. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(1), one O(4), two equivalent O(5), and three equivalent O(3) atoms. In the third Er site, Er(3) is bonded in a 7-coordinate geometry to two equivalent O(2), two equivalent O(5), and three equivalent O(1) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Er(2) and three equivalent Er(3) atoms. In the second O site, O(2) is bonded to two equivalent Er(1) and two equivalent Er(3) atoms to form OEr4 tetrahedra that share corners with two equivalent O(4)Er6 octahedra, corners with two equivalent O(5)Er5 square pyramids, corners with two equivalent O(2)Er4 tetrahedra, corners with two equivalent O(3)Er4 tetrahedra,  an edgeedge with one O(4)Er6 octahedra, edges with two equivalent O(5)Er5 square pyramids, and  an edgeedge with one O(2)Er4 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the third O site, O(3) is bonded to one Er(1) and three equivalent Er(2) atoms to form OEr4 tetrahedra that share  a cornercorner with one O(4)Er6 octahedra, corners with five equivalent O(5)Er5 square pyramids, corners with two equivalent O(2)Er4 tetrahedra, corners with two equivalent O(3)Er4 tetrahedra, edges with two equivalent O(4)Er6 octahedra,  an edgeedge with one O(5)Er5 square pyramid, and edges with two equivalent O(3)Er4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the fourth O site, O(4) is bonded to two equivalent Er(2) and four equivalent Er(1) atoms to form OEr6 octahedra that share corners with two equivalent O(3)Er4 tetrahedra, corners with four equivalent O(2)Er4 tetrahedra, edges with two equivalent O(4)Er6 octahedra, edges with four equivalent O(5)Er5 square pyramids, edges with two equivalent O(2)Er4 tetrahedra, and edges with four equivalent O(3)Er4 tetrahedra. In the fifth O site, O(5) is bonded to one Er(1), two equivalent Er(2), and two equivalent Er(3) atoms to form distorted OEr5 square pyramids that share corners with two equivalent O(2)Er4 tetrahedra, corners with five equivalent O(3)Er4 tetrahedra, edges with two equivalent O(4)Er6 octahedra, edges with two equivalent O(5)Er5 square pyramids,  an edgeedge with one O(3)Er4 tetrahedra, and edges with two equivalent O(2)Er4 tetrahedra. is represented by the CIF file [CIF]
data_Er2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.432
_cell_length_b   7.102
_cell_length_c   8.484
_cell_angle_alpha   99.893
_cell_angle_beta   90.000
_cell_angle_gamma   103.978
_symmetry_Int_Tables_number   1
_cell_volume   197.497
_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
  Er  Er0  1  0.533  0.066  0.813  1.0
  Er  Er1  1  0.467  0.934  0.187  1.0
  Er  Er2  1  0.809  0.618  0.863  1.0
  Er  Er3  1  0.191  0.382  0.137  1.0
  Er  Er4  1  0.865  0.730  0.513  1.0
  Er  Er5  1  0.135  0.270  0.487  1.0
  O  O6  1  0.706  0.412  0.624  1.0
  O  O7  1  0.294  0.588  0.376  1.0
  O  O8  1  0.970  0.941  0.343  1.0
  O  O9  1  0.030  0.059  0.657  1.0
  O  O10  1  0.675  0.349  0.969  1.0
  O  O11  1  0.325  0.651  0.031  1.0
  O  O12  1  0.000  0.000  0.000  1.0
  O  O13  1  0.372  0.745  0.718  1.0
  O  O14  1  0.628  0.255  0.282  1.0
[/CIF]
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The compound described by Er2O3 crystallizes in the monoclinic C2/m space group. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(3), one O(5), two equivalent O(2), and two equivalent O(4) atoms to form a mixture of distorted corner and edge-sharing ErO6 octahedra. The corner-sharing octahedra are not tilted. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(1), one O(4), two equivalent O(5), and three equivalent O(3) atoms. In the third Er site, Er(3) is bonded in a 7-coordinate geometry to two equivalent O(2), two equivalent O(5), and three equivalent O(1) atoms. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Er(2) and three equivalent Er(3) atoms. In the second O site, O(2) is bonded to two equivalent Er(1) and two equivalent Er(3) atoms to form OEr4 tetrahedra that share corners with two equivalent O(4)Er6 octahedra, corners with two equivalent O(5)Er5 square pyramids, corners with two equivalent O(2)Er4 tetrahedra, corners with two equivalent O(3)Er4 tetrahedra,  an edgeedge with one O(4)Er6 octahedra, edges with two equivalent O(5)Er5 square pyramids, and  an edgeedge with one O(2)Er4 tetrahedra. The corner-sharing octahedral tilt angles are 14°. In the third O site, O(3) is bonded to one Er(1) and three equivalent Er(2) atoms to form OEr4 tetrahedra that share  a cornercorner with one O(4)Er6 octahedra, corners with five equivalent O(5)Er5 square pyramids, corners with two equivalent O(2)Er4 tetrahedra, corners with two equivalent O(3)Er4 tetrahedra, edges with two equivalent O(4)Er6 octahedra,  an edgeedge with one O(5)Er5 square pyramid, and edges with two equivalent O(3)Er4 tetrahedra. The corner-sharing octahedral tilt angles are 49°. In the fourth O site, O(4) is bonded to two equivalent Er(2) and four equivalent Er(1) atoms to form OEr6 octahedra that share corners with two equivalent O(3)Er4 tetrahedra, corners with four equivalent O(2)Er4 tetrahedra, edges with two equivalent O(4)Er6 octahedra, edges with four equivalent O(5)Er5 square pyramids, edges with two equivalent O(2)Er4 tetrahedra, and edges with four equivalent O(3)Er4 tetrahedra. In the fifth O site, O(5) is bonded to one Er(1), two equivalent Er(2), and two equivalent Er(3) atoms to form distorted OEr5 square pyramids that share corners with two equivalent O(2)Er4 tetrahedra, corners with five equivalent O(3)Er4 tetrahedra, edges with two equivalent O(4)Er6 octahedra, edges with two equivalent O(5)Er5 square pyramids,  an edgeedge with one O(3)Er4 tetrahedra, and edges with two equivalent O(2)Er4 tetrahedra. is represented by the CIF file [CIF]
data_Er2O3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.432
_cell_length_b   7.102
_cell_length_c   8.484
_cell_angle_alpha   99.893
_cell_angle_beta   90.000
_cell_angle_gamma   103.978
_symmetry_Int_Tables_number   1
_cell_volume   197.497
_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
  Er  Er0  1  0.533  0.066  0.813  1.0
  Er  Er1  1  0.467  0.934  0.187  1.0
  Er  Er2  1  0.809  0.618  0.863  1.0
  Er  Er3  1  0.191  0.382  0.137  1.0
  Er  Er4  1  0.865  0.730  0.513  1.0
  Er  Er5  1  0.135  0.270  0.487  1.0
  O  O6  1  0.706  0.412  0.624  1.0
  O  O7  1  0.294  0.588  0.376  1.0
  O  O8  1  0.970  0.941  0.343  1.0
  O  O9  1  0.030  0.059  0.657  1.0
  O  O10  1  0.675  0.349  0.969  1.0
  O  O11  1  0.325  0.651  0.031  1.0
  O  O12  1  0.000  0.000  0.000  1.0
  O  O13  1  0.372  0.745  0.718  1.0
  O  O14  1  0.628  0.255  0.282  1.0
[/CIF]
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