The material described by Er2Nb2O7 crystallizes in the cubic Fd-3m space group. Er(1) is bonded in a body-centered cubic geometry to two equivalent O(2) and six equivalent O(1) atoms. Nb(1) is bonded to six equivalent O(1) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles are 58°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Nb(1) atoms to form OEr2Nb2 tetrahedra that share corners with two equivalent O(2)Er4 tetrahedra, corners with twelve equivalent O(1)Er2Nb2 tetrahedra,  an edgeedge with one O(2)Er4 tetrahedra, and edges with four equivalent O(1)Er2Nb2 tetrahedra. In the second O site, O(2) is bonded to four equivalent Er(1) atoms to form OEr4 tetrahedra that share corners with four equivalent O(2)Er4 tetrahedra, corners with twelve equivalent O(1)Er2Nb2 tetrahedra, and edges with six equivalent O(1)Er2Nb2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2Nb2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.291
_cell_length_b   7.291
_cell_length_c   7.291
_cell_angle_alpha   60.000
_cell_angle_beta   60.000
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   274.012
_cell_formula_units_Z   2
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  0.125  0.125  0.125  1.0
  Er  Er1  1  0.125  0.125  0.625  1.0
  Er  Er2  1  0.625  0.125  0.125  1.0
  Er  Er3  1  0.125  0.625  0.125  1.0
  Nb  Nb4  1  0.625  0.125  0.625  1.0
  Nb  Nb5  1  0.625  0.625  0.125  1.0
  Nb  Nb6  1  0.125  0.625  0.625  1.0
  Nb  Nb7  1  0.625  0.625  0.625  1.0
  O  O8  1  0.973  0.527  0.973  1.0
  O  O9  1  0.250  0.250  0.250  1.0
  O  O10  1  0.723  0.277  0.723  1.0
  O  O11  1  0.723  0.723  0.277  1.0
  O  O12  1  0.277  0.723  0.723  1.0
  O  O13  1  0.973  0.973  0.527  1.0
  O  O14  1  0.527  0.973  0.973  1.0
  O  O15  1  0.973  0.527  0.527  1.0
  O  O16  1  0.527  0.527  0.973  1.0
  O  O17  1  0.723  0.277  0.277  1.0
  O  O18  1  0.277  0.277  0.723  1.0
  O  O19  1  0.000  0.000  0.000  1.0
  O  O20  1  0.277  0.723  0.277  1.0
  O  O21  1  0.527  0.973  0.527  1.0
[/CIF]
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The material described by Er2Nb2O7 crystallizes in the cubic Fd-3m space group. Er(1) is bonded in a body-centered cubic geometry to two equivalent O(2) and six equivalent O(1) atoms. Nb(1) is bonded to six equivalent O(1) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles are 58°. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Nb(1) atoms to form OEr2Nb2 tetrahedra that share corners with two equivalent O(2)Er4 tetrahedra, corners with twelve equivalent O(1)Er2Nb2 tetrahedra,  an edgeedge with one O(2)Er4 tetrahedra, and edges with four equivalent O(1)Er2Nb2 tetrahedra. In the second O site, O(2) is bonded to four equivalent Er(1) atoms to form OEr4 tetrahedra that share corners with four equivalent O(2)Er4 tetrahedra, corners with twelve equivalent O(1)Er2Nb2 tetrahedra, and edges with six equivalent O(1)Er2Nb2 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2Nb2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.291
_cell_length_b   7.291
_cell_length_c   7.291
_cell_angle_alpha   60.000
_cell_angle_beta   60.000
_cell_angle_gamma   60.000
_symmetry_Int_Tables_number   1
_cell_volume   274.012
_cell_formula_units_Z   2
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  0.125  0.125  0.125  1.0
  Er  Er1  1  0.125  0.125  0.625  1.0
  Er  Er2  1  0.625  0.125  0.125  1.0
  Er  Er3  1  0.125  0.625  0.125  1.0
  Nb  Nb4  1  0.625  0.125  0.625  1.0
  Nb  Nb5  1  0.625  0.625  0.125  1.0
  Nb  Nb6  1  0.125  0.625  0.625  1.0
  Nb  Nb7  1  0.625  0.625  0.625  1.0
  O  O8  1  0.973  0.527  0.973  1.0
  O  O9  1  0.250  0.250  0.250  1.0
  O  O10  1  0.723  0.277  0.723  1.0
  O  O11  1  0.723  0.723  0.277  1.0
  O  O12  1  0.277  0.723  0.723  1.0
  O  O13  1  0.973  0.973  0.527  1.0
  O  O14  1  0.527  0.973  0.973  1.0
  O  O15  1  0.973  0.527  0.527  1.0
  O  O16  1  0.527  0.527  0.973  1.0
  O  O17  1  0.723  0.277  0.277  1.0
  O  O18  1  0.277  0.277  0.723  1.0
  O  O19  1  0.000  0.000  0.000  1.0
  O  O20  1  0.277  0.723  0.277  1.0
  O  O21  1  0.527  0.973  0.527  1.0
[/CIF]
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