The compound described by EuZr4O9 crystallizes in the orthorhombic Imm2 space group. Eu(1) is bonded in a distorted hexagonal planar geometry to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a body-centered cubic geometry to one O(1), one O(4), three equivalent O(2), and three equivalent O(3) atoms. In the second Zr site, Zr(2) is bonded to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of distorted edge and corner-sharing ZrO7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1), one Zr(1), and two equivalent Zr(2) atoms to form OEuZr3 tetrahedra that share  a cornercorner with one O(2)Zr4 tetrahedra, corners with three equivalent O(1)EuZr3 tetrahedra, corners with three equivalent O(4)EuZr3 tetrahedra, corners with five equivalent O(3)Zr4 tetrahedra, corners with four equivalent O(5)Eu2Zr2 trigonal pyramids, edges with two equivalent O(4)EuZr3 tetrahedra, and edges with two equivalent O(2)Zr4 tetrahedra. In the second O site, O(2) is bonded to one Zr(2) and three equivalent Zr(1) atoms to form OZr4 tetrahedra that share  a cornercorner with one O(1)EuZr3 tetrahedra, corners with two equivalent O(3)Zr4 tetrahedra, corners with five equivalent O(4)EuZr3 tetrahedra, corners with six equivalent O(2)Zr4 tetrahedra,  a cornercorner with one O(5)Eu2Zr2 trigonal pyramid, edges with two equivalent O(1)EuZr3 tetrahedra, and edges with four equivalent O(3)Zr4 tetrahedra. In the third O site, O(3) is bonded to one Zr(2) and three equivalent Zr(1) atoms to form OZr4 tetrahedra that share  a cornercorner with one O(4)EuZr3 tetrahedra, corners with two equivalent O(2)Zr4 tetrahedra, corners with five equivalent O(1)EuZr3 tetrahedra, corners with six equivalent O(3)Zr4 tetrahedra,  a cornercorner with one O(5)Eu2Zr2 trigonal pyramid, edges with two equivalent O(4)EuZr3 tetrahedra, and edges with four equivalent O(2)Zr4 tetrahedra. In the fourth O site, O(4) is bonded to one Eu(1), one Zr(1), and two equivalent Zr(2) atoms to form OEuZr3 tetrahedra that share  a cornercorner with one O(3)Zr4 tetrahedra, corners with three equivalent O(1)EuZr3 tetrahedra, corners with three equivalent O(4)EuZr3 tetrahedra, corners with five equivalent O(2)Zr4 tetrahedra, edges with two equivalent O(1)EuZr3 tetrahedra, edges with two equivalent O(3)Zr4 tetrahedra, and edges with two equivalent O(5)Eu2Zr2 trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Eu(1) and two equivalent Zr(2) atoms to form distorted OEu2Zr2 trigonal pyramids that share corners with two equivalent O(2)Zr4 tetrahedra, corners with two equivalent O(3)Zr4 tetrahedra, corners with eight equivalent O(1)EuZr3 tetrahedra, corners with two equivalent O(5)Eu2Zr2 trigonal pyramids, and edges with four equivalent O(4)EuZr3 tetrahedra. is represented by the CIF file [CIF]
data_EuZr4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.052
_cell_length_b   10.052
_cell_length_c   10.052
_cell_angle_alpha   159.472
_cell_angle_beta   149.710
_cell_angle_gamma   36.871
_symmetry_Int_Tables_number   1
_cell_volume   179.428
_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  0.466  0.500  0.966  1.0
  Zr  Zr1  1  0.722  0.696  0.025  1.0
  Zr  Zr2  1  0.915  0.888  0.027  1.0
  Zr  Zr3  1  0.329  0.304  0.025  1.0
  Zr  Zr4  1  0.138  0.112  0.027  1.0
  O  O5  1  0.672  0.401  0.271  1.0
  O  O6  1  0.570  0.800  0.770  1.0
  O  O7  1  0.870  0.599  0.271  1.0
  O  O8  1  0.068  0.797  0.271  1.0
  O  O9  1  0.970  0.200  0.770  1.0
  O  O10  1  0.155  0.390  0.765  1.0
  O  O11  1  0.375  0.610  0.765  1.0
  O  O12  1  0.474  0.203  0.271  1.0
  O  O13  1  0.132  0.000  0.132  1.0
[/CIF]
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The compound described by EuZr4O9 crystallizes in the orthorhombic Imm2 space group. Eu(1) is bonded in a distorted hexagonal planar geometry to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a body-centered cubic geometry to one O(1), one O(4), three equivalent O(2), and three equivalent O(3) atoms. In the second Zr site, Zr(2) is bonded to one O(2), one O(3), one O(5), two equivalent O(1), and two equivalent O(4) atoms to form a mixture of distorted edge and corner-sharing ZrO7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Eu(1), one Zr(1), and two equivalent Zr(2) atoms to form OEuZr3 tetrahedra that share  a cornercorner with one O(2)Zr4 tetrahedra, corners with three equivalent O(1)EuZr3 tetrahedra, corners with three equivalent O(4)EuZr3 tetrahedra, corners with five equivalent O(3)Zr4 tetrahedra, corners with four equivalent O(5)Eu2Zr2 trigonal pyramids, edges with two equivalent O(4)EuZr3 tetrahedra, and edges with two equivalent O(2)Zr4 tetrahedra. In the second O site, O(2) is bonded to one Zr(2) and three equivalent Zr(1) atoms to form OZr4 tetrahedra that share  a cornercorner with one O(1)EuZr3 tetrahedra, corners with two equivalent O(3)Zr4 tetrahedra, corners with five equivalent O(4)EuZr3 tetrahedra, corners with six equivalent O(2)Zr4 tetrahedra,  a cornercorner with one O(5)Eu2Zr2 trigonal pyramid, edges with two equivalent O(1)EuZr3 tetrahedra, and edges with four equivalent O(3)Zr4 tetrahedra. In the third O site, O(3) is bonded to one Zr(2) and three equivalent Zr(1) atoms to form OZr4 tetrahedra that share  a cornercorner with one O(4)EuZr3 tetrahedra, corners with two equivalent O(2)Zr4 tetrahedra, corners with five equivalent O(1)EuZr3 tetrahedra, corners with six equivalent O(3)Zr4 tetrahedra,  a cornercorner with one O(5)Eu2Zr2 trigonal pyramid, edges with two equivalent O(4)EuZr3 tetrahedra, and edges with four equivalent O(2)Zr4 tetrahedra. In the fourth O site, O(4) is bonded to one Eu(1), one Zr(1), and two equivalent Zr(2) atoms to form OEuZr3 tetrahedra that share  a cornercorner with one O(3)Zr4 tetrahedra, corners with three equivalent O(1)EuZr3 tetrahedra, corners with three equivalent O(4)EuZr3 tetrahedra, corners with five equivalent O(2)Zr4 tetrahedra, edges with two equivalent O(1)EuZr3 tetrahedra, edges with two equivalent O(3)Zr4 tetrahedra, and edges with two equivalent O(5)Eu2Zr2 trigonal pyramids. In the fifth O site, O(5) is bonded to two equivalent Eu(1) and two equivalent Zr(2) atoms to form distorted OEu2Zr2 trigonal pyramids that share corners with two equivalent O(2)Zr4 tetrahedra, corners with two equivalent O(3)Zr4 tetrahedra, corners with eight equivalent O(1)EuZr3 tetrahedra, corners with two equivalent O(5)Eu2Zr2 trigonal pyramids, and edges with four equivalent O(4)EuZr3 tetrahedra. is represented by the CIF file [CIF]
data_EuZr4O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.052
_cell_length_b   10.052
_cell_length_c   10.052
_cell_angle_alpha   159.472
_cell_angle_beta   149.710
_cell_angle_gamma   36.871
_symmetry_Int_Tables_number   1
_cell_volume   179.428
_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  0.466  0.500  0.966  1.0
  Zr  Zr1  1  0.722  0.696  0.025  1.0
  Zr  Zr2  1  0.915  0.888  0.027  1.0
  Zr  Zr3  1  0.329  0.304  0.025  1.0
  Zr  Zr4  1  0.138  0.112  0.027  1.0
  O  O5  1  0.672  0.401  0.271  1.0
  O  O6  1  0.570  0.800  0.770  1.0
  O  O7  1  0.870  0.599  0.271  1.0
  O  O8  1  0.068  0.797  0.271  1.0
  O  O9  1  0.970  0.200  0.770  1.0
  O  O10  1  0.155  0.390  0.765  1.0
  O  O11  1  0.375  0.610  0.765  1.0
  O  O12  1  0.474  0.203  0.271  1.0
  O  O13  1  0.132  0.000  0.132  1.0
[/CIF]
.