The structure described by Eu3Al2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. In the second Eu site, Eu(2) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form EuO12 cuboctahedra that share corners with four equivalent Eu(2)O12 cuboctahedra, faces with four equivalent Eu(2)O12 cuboctahedra, and faces with eight equivalent Al(1)O6 octahedra. Al(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form AlO6 octahedra that share corners with five equivalent Al(1)O6 octahedra and faces with four equivalent Eu(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Eu(1), two equivalent Eu(2), and two equivalent Al(1) atoms to form distorted OEu4Al2 octahedra that share corners with four equivalent O(3)Eu4Al2 octahedra, corners with six equivalent O(2)Eu5Al octahedra, corners with eight equivalent O(1)Eu4Al2 octahedra, edges with three equivalent O(1)Eu4Al2 octahedra, faces with two equivalent O(3)Eu4Al2 octahedra, faces with two equivalent O(2)Eu5Al octahedra, and faces with four equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the second O site, O(2) is bonded to five equivalent Eu(1) and one Al(1) atom to form distorted OEu5Al octahedra that share  a cornercorner with one O(3)Eu4Al2 octahedra, corners with four equivalent O(2)Eu5Al octahedra, corners with twelve equivalent O(1)Eu4Al2 octahedra, edges with eight equivalent O(2)Eu5Al octahedra, and faces with four equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-53°. In the third O site, O(3) is bonded to four equivalent Eu(2) and two equivalent Al(1) atoms to form distorted OEu4Al2 octahedra that share corners with two equivalent O(2)Eu5Al octahedra, corners with four equivalent O(3)Eu4Al2 octahedra, corners with sixteen equivalent O(1)Eu4Al2 octahedra, edges with four equivalent O(3)Eu4Al2 octahedra, and faces with eight equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the fourth O site, O(3) is bonded to four equivalent Eu(2) and two equivalent Al(1) atoms to form distorted OEu4Al2 octahedra that share corners with two equivalent O(2)Eu5Al octahedra, corners with four equivalent O(3)Eu4Al2 octahedra, corners with sixteen equivalent O(1)Eu4Al2 octahedra, edges with four equivalent O(3)Eu4Al2 octahedra, and faces with eight equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Eu3Al2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.198
_cell_length_b   10.198
_cell_length_c   10.198
_cell_angle_alpha   159.025
_cell_angle_beta   159.025
_cell_angle_gamma   29.833
_symmetry_Int_Tables_number   1
_cell_volume   135.810
_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
  Eu  Eu0  1  0.318  0.318  0.000  1.0
  Eu  Eu1  1  0.682  0.682  0.000  1.0
  Eu  Eu2  1  0.500  0.500  0.000  1.0
  Al  Al3  1  0.095  0.095  0.000  1.0
  Al  Al4  1  0.905  0.905  0.000  1.0
  O  O5  1  0.597  0.097  0.500  1.0
  O  O6  1  0.403  0.903  0.500  1.0
  O  O7  1  0.097  0.597  0.500  1.0
  O  O8  1  0.903  0.403  0.500  1.0
  O  O9  1  0.198  0.198  0.000  1.0
  O  O10  1  0.802  0.802  0.000  1.0
  O  O11  1  0.000  0.000  0.000  1.0
[/CIF]
.
The structure described by Eu3Al2O7 crystallizes in the tetragonal I4/mmm space group. There are two inequivalent Eu sites. In the first Eu site, Eu(1) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. In the second Eu site, Eu(2) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form EuO12 cuboctahedra that share corners with four equivalent Eu(2)O12 cuboctahedra, faces with four equivalent Eu(2)O12 cuboctahedra, and faces with eight equivalent Al(1)O6 octahedra. Al(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form AlO6 octahedra that share corners with five equivalent Al(1)O6 octahedra and faces with four equivalent Eu(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-2°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Eu(1), two equivalent Eu(2), and two equivalent Al(1) atoms to form distorted OEu4Al2 octahedra that share corners with four equivalent O(3)Eu4Al2 octahedra, corners with six equivalent O(2)Eu5Al octahedra, corners with eight equivalent O(1)Eu4Al2 octahedra, edges with three equivalent O(1)Eu4Al2 octahedra, faces with two equivalent O(3)Eu4Al2 octahedra, faces with two equivalent O(2)Eu5Al octahedra, and faces with four equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the second O site, O(2) is bonded to five equivalent Eu(1) and one Al(1) atom to form distorted OEu5Al octahedra that share  a cornercorner with one O(3)Eu4Al2 octahedra, corners with four equivalent O(2)Eu5Al octahedra, corners with twelve equivalent O(1)Eu4Al2 octahedra, edges with eight equivalent O(2)Eu5Al octahedra, and faces with four equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-53°. In the third O site, O(3) is bonded to four equivalent Eu(2) and two equivalent Al(1) atoms to form distorted OEu4Al2 octahedra that share corners with two equivalent O(2)Eu5Al octahedra, corners with four equivalent O(3)Eu4Al2 octahedra, corners with sixteen equivalent O(1)Eu4Al2 octahedra, edges with four equivalent O(3)Eu4Al2 octahedra, and faces with eight equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. In the fourth O site, O(3) is bonded to four equivalent Eu(2) and two equivalent Al(1) atoms to form distorted OEu4Al2 octahedra that share corners with two equivalent O(2)Eu5Al octahedra, corners with four equivalent O(3)Eu4Al2 octahedra, corners with sixteen equivalent O(1)Eu4Al2 octahedra, edges with four equivalent O(3)Eu4Al2 octahedra, and faces with eight equivalent O(1)Eu4Al2 octahedra. The corner-sharing octahedral tilt angles range from 0-61°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Eu3Al2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.198
_cell_length_b   10.198
_cell_length_c   10.198
_cell_angle_alpha   159.025
_cell_angle_beta   159.025
_cell_angle_gamma   29.833
_symmetry_Int_Tables_number   1
_cell_volume   135.810
_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
  Eu  Eu0  1  0.318  0.318  0.000  1.0
  Eu  Eu1  1  0.682  0.682  0.000  1.0
  Eu  Eu2  1  0.500  0.500  0.000  1.0
  Al  Al3  1  0.095  0.095  0.000  1.0
  Al  Al4  1  0.905  0.905  0.000  1.0
  O  O5  1  0.597  0.097  0.500  1.0
  O  O6  1  0.403  0.903  0.500  1.0
  O  O7  1  0.097  0.597  0.500  1.0
  O  O8  1  0.903  0.403  0.500  1.0
  O  O9  1  0.198  0.198  0.000  1.0
  O  O10  1  0.802  0.802  0.000  1.0
  O  O11  1  0.000  0.000  0.000  1.0
[/CIF]
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