The material described by Zr3Er4O12 crystallizes in the triclinic P-1 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form distorted ErO7 pentagonal bipyramids that share  a cornercorner with one Zr(1)O6 octahedra,  an edgeedge with one Zr(1)O6 octahedra, and edges with two equivalent Er(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(2), one O(5), one O(6), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form ZrO6 octahedra that share corners with two equivalent Er(1)O7 pentagonal bipyramids and edges with two equivalent Er(1)O7 pentagonal bipyramids. In the second Zr site, Zr(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(6), and two equivalent O(5) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one Zr(1), and one Zr(2) atom. In the second O site, O(2) is bonded to one Er(2), two equivalent Er(1), and one Zr(1) atom to form distorted OEr3Zr tetrahedra that share  a cornercorner with one O(2)Er3Zr tetrahedra, corners with two equivalent O(3)Er2Zr2 tetrahedra, corners with two equivalent O(4)Er3Zr tetrahedra, corners with three equivalent O(5)Er2Zr2 tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. In the third O site, O(3) is bonded to two equivalent Er(2), one Zr(1), and one Zr(2) atom to form distorted OEr2Zr2 tetrahedra that share  a cornercorner with one O(3)Er2Zr2 tetrahedra, corners with two equivalent O(5)Er2Zr2 tetrahedra, corners with two equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(4)Er3Zr tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra, and  an edgeedge with one O(4)Er3Zr tetrahedra. In the fourth O site, O(4) is bonded to one Er(1), two equivalent Er(2), and one Zr(2) atom to form OEr3Zr tetrahedra that share corners with two equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(3)Er2Zr2 tetrahedra, corners with three equivalent O(5)Er2Zr2 tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. In the fifth O site, O(5) is bonded to one Er(1), one Er(2), and two equivalent Zr(2) atoms to form OEr2Zr2 tetrahedra that share corners with two equivalent O(3)Er2Zr2 tetrahedra, corners with three equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(4)Er3Zr tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. In the sixth O site, O(6) is bonded to one Er(2), two equivalent Er(1), and one Zr(2) atom to form distorted OEr3Zr tetrahedra that share corners with three equivalent O(3)Er2Zr2 tetrahedra, corners with three equivalent O(5)Er2Zr2 tetrahedra, corners with three equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(4)Er3Zr tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. is represented by the CIF file [CIF]
data_Er4Zr3O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.284
_cell_length_b   6.320
_cell_length_c   6.472
_cell_angle_alpha   99.814
_cell_angle_beta   98.748
_cell_angle_gamma   99.530
_symmetry_Int_Tables_number   1
_cell_volume   245.445
_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
  Er  Er0  1  0.389  0.699  0.865  1.0
  Er  Er1  1  0.695  0.865  0.390  1.0
  Er  Er2  1  0.611  0.301  0.135  1.0
  Er  Er3  1  0.305  0.135  0.610  1.0
  Zr  Zr4  1  0.000  0.000  0.000  1.0
  Zr  Zr5  1  0.850  0.396  0.673  1.0
  Zr  Zr6  1  0.150  0.604  0.327  1.0
  O  O7  1  0.030  0.677  0.889  1.0
  O  O8  1  0.684  0.931  0.060  1.0
  O  O9  1  0.920  0.082  0.691  1.0
  O  O10  1  0.970  0.323  0.111  1.0
  O  O11  1  0.316  0.069  0.940  1.0
  O  O12  1  0.080  0.918  0.309  1.0
  O  O13  1  0.586  0.187  0.433  1.0
  O  O14  1  0.173  0.429  0.574  1.0
  O  O15  1  0.415  0.582  0.179  1.0
  O  O16  1  0.414  0.813  0.567  1.0
  O  O17  1  0.827  0.571  0.426  1.0
  O  O18  1  0.585  0.418  0.821  1.0
[/CIF]
.
The material described by Zr3Er4O12 crystallizes in the triclinic P-1 space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(1), one O(4), one O(5), two equivalent O(2), and two equivalent O(6) atoms to form distorted ErO7 pentagonal bipyramids that share  a cornercorner with one Zr(1)O6 octahedra,  an edgeedge with one Zr(1)O6 octahedra, and edges with two equivalent Er(1)O7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 50°. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(2), one O(5), one O(6), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form ZrO6 octahedra that share corners with two equivalent Er(1)O7 pentagonal bipyramids and edges with two equivalent Er(1)O7 pentagonal bipyramids. In the second Zr site, Zr(2) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(6), and two equivalent O(5) atoms. There are six inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Er(1), one Zr(1), and one Zr(2) atom. In the second O site, O(2) is bonded to one Er(2), two equivalent Er(1), and one Zr(1) atom to form distorted OEr3Zr tetrahedra that share  a cornercorner with one O(2)Er3Zr tetrahedra, corners with two equivalent O(3)Er2Zr2 tetrahedra, corners with two equivalent O(4)Er3Zr tetrahedra, corners with three equivalent O(5)Er2Zr2 tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. In the third O site, O(3) is bonded to two equivalent Er(2), one Zr(1), and one Zr(2) atom to form distorted OEr2Zr2 tetrahedra that share  a cornercorner with one O(3)Er2Zr2 tetrahedra, corners with two equivalent O(5)Er2Zr2 tetrahedra, corners with two equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(4)Er3Zr tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra, and  an edgeedge with one O(4)Er3Zr tetrahedra. In the fourth O site, O(4) is bonded to one Er(1), two equivalent Er(2), and one Zr(2) atom to form OEr3Zr tetrahedra that share corners with two equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(3)Er2Zr2 tetrahedra, corners with three equivalent O(5)Er2Zr2 tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. In the fifth O site, O(5) is bonded to one Er(1), one Er(2), and two equivalent Zr(2) atoms to form OEr2Zr2 tetrahedra that share corners with two equivalent O(3)Er2Zr2 tetrahedra, corners with three equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(4)Er3Zr tetrahedra, corners with three equivalent O(6)Er3Zr tetrahedra,  an edgeedge with one O(3)Er2Zr2 tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. In the sixth O site, O(6) is bonded to one Er(2), two equivalent Er(1), and one Zr(2) atom to form distorted OEr3Zr tetrahedra that share corners with three equivalent O(3)Er2Zr2 tetrahedra, corners with three equivalent O(5)Er2Zr2 tetrahedra, corners with three equivalent O(2)Er3Zr tetrahedra, corners with three equivalent O(4)Er3Zr tetrahedra,  an edgeedge with one O(5)Er2Zr2 tetrahedra,  an edgeedge with one O(2)Er3Zr tetrahedra,  an edgeedge with one O(4)Er3Zr tetrahedra, and  an edgeedge with one O(6)Er3Zr tetrahedra. is represented by the CIF file [CIF]
data_Er4Zr3O12
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.284
_cell_length_b   6.320
_cell_length_c   6.472
_cell_angle_alpha   99.814
_cell_angle_beta   98.748
_cell_angle_gamma   99.530
_symmetry_Int_Tables_number   1
_cell_volume   245.445
_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
  Er  Er0  1  0.389  0.699  0.865  1.0
  Er  Er1  1  0.695  0.865  0.390  1.0
  Er  Er2  1  0.611  0.301  0.135  1.0
  Er  Er3  1  0.305  0.135  0.610  1.0
  Zr  Zr4  1  0.000  0.000  0.000  1.0
  Zr  Zr5  1  0.850  0.396  0.673  1.0
  Zr  Zr6  1  0.150  0.604  0.327  1.0
  O  O7  1  0.030  0.677  0.889  1.0
  O  O8  1  0.684  0.931  0.060  1.0
  O  O9  1  0.920  0.082  0.691  1.0
  O  O10  1  0.970  0.323  0.111  1.0
  O  O11  1  0.316  0.069  0.940  1.0
  O  O12  1  0.080  0.918  0.309  1.0
  O  O13  1  0.586  0.187  0.433  1.0
  O  O14  1  0.173  0.429  0.574  1.0
  O  O15  1  0.415  0.582  0.179  1.0
  O  O16  1  0.414  0.813  0.567  1.0
  O  O17  1  0.827  0.571  0.426  1.0
  O  O18  1  0.585  0.418  0.821  1.0
[/CIF]
.