The material structure described by Ba5Er8Zn4O21 crystallizes in the tetragonal I4/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(2), four equivalent O(1), and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to two equivalent O(4) and eight equivalent O(2) atoms. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(4), two equivalent O(1), and four equivalent O(2) atoms to form distorted ErO7 pentagonal bipyramids that share  a cornercorner with one Er(1)O7 pentagonal bipyramid, corners with two equivalent Zn(1)O5 trigonal bipyramids, edges with two equivalent Zn(1)O5 trigonal bipyramids, and faces with two equivalent Er(1)O7 pentagonal bipyramids. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(2), and four equivalent O(1) atoms. Zn(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted ZnO5 trigonal bipyramids that share corners with two equivalent Er(1)O7 pentagonal bipyramids and edges with two equivalent Er(1)O7 pentagonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Er(1), two equivalent Er(2), and one Zn(1) atom. In the second O site, O(2) is bonded to one Ba(1), one Ba(2), one Er(2), two equivalent Er(1), and one Zn(1) atom to form distorted OBa2Er3Zn octahedra that share  a cornercorner with one O(4)Ba2Er4 octahedra, corners with three equivalent O(3)Ba4ErZn octahedra, corners with six equivalent O(2)Ba2Er3Zn octahedra, edges with two equivalent O(2)Ba2Er3Zn octahedra,  a faceface with one O(4)Ba2Er4 octahedra,  a faceface with one O(3)Ba4ErZn octahedra, and faces with two equivalent O(2)Ba2Er3Zn octahedra. The corner-sharing octahedral tilt angles range from 0-76°. In the third O site, O(3) is bonded to four equivalent Ba(1), one Er(2), and one Zn(1) atom to form distorted OBa4ErZn octahedra that share corners with two equivalent O(3)Ba4ErZn octahedra, corners with six equivalent O(2)Ba2Er3Zn octahedra, edges with five equivalent O(3)Ba4ErZn octahedra, and faces with two equivalent O(2)Ba2Er3Zn octahedra. The corner-sharing octahedral tilt angles range from 6-60°. In the fourth O site, O(4) is bonded to two equivalent Ba(2) and four equivalent Er(1) atoms to form OBa2Er4 octahedra that share corners with two equivalent O(4)Ba2Er4 octahedra, corners with eight equivalent O(2)Ba2Er3Zn octahedra, and faces with eight equivalent O(2)Ba2Er3Zn octahedra. The corner-sharing octahedral tilt angles range from 0-61°. is represented by the CIF file [CIF]
data_Ba5Er8Zn4O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.176
_cell_length_b   10.176
_cell_length_c   10.176
_cell_angle_alpha   94.535
_cell_angle_beta   94.535
_cell_angle_gamma   147.339
_symmetry_Int_Tables_number   1
_cell_volume   545.729
_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
  Ba  Ba0  1  0.535  0.860  0.396  1.0
  Ba  Ba1  1  0.860  0.465  0.325  1.0
  Ba  Ba2  1  0.140  0.535  0.675  1.0
  Ba  Ba3  1  0.465  0.140  0.604  1.0
  Ba  Ba4  1  0.000  0.000  0.000  1.0
  Er  Er5  1  0.411  0.642  0.053  1.0
  Er  Er6  1  0.642  0.589  0.230  1.0
  Er  Er7  1  0.358  0.411  0.770  1.0
  Er  Er8  1  0.589  0.358  0.947  1.0
  Er  Er9  1  0.248  0.832  0.079  1.0
  Er  Er10  1  0.832  0.752  0.584  1.0
  Er  Er11  1  0.168  0.248  0.416  1.0
  Er  Er12  1  0.752  0.168  0.921  1.0
  Zn  Zn13  1  0.041  0.750  0.791  1.0
  Zn  Zn14  1  0.750  0.959  0.709  1.0
  Zn  Zn15  1  0.250  0.041  0.291  1.0
  Zn  Zn16  1  0.959  0.250  0.209  1.0
  O  O17  1  0.900  0.494  0.892  1.0
  O  O18  1  0.494  0.602  0.595  1.0
  O  O19  1  0.007  0.900  0.405  1.0
  O  O20  1  0.602  0.007  0.108  1.0
  O  O21  1  0.100  0.506  0.108  1.0
  O  O22  1  0.506  0.398  0.405  1.0
  O  O23  1  0.993  0.100  0.595  1.0
  O  O24  1  0.398  0.993  0.892  1.0
  O  O25  1  0.073  0.299  0.871  1.0
  O  O26  1  0.299  0.428  0.226  1.0
  O  O27  1  0.203  0.073  0.774  1.0
  O  O28  1  0.428  0.203  0.129  1.0
  O  O29  1  0.927  0.701  0.129  1.0
  O  O30  1  0.701  0.572  0.774  1.0
  O  O31  1  0.797  0.927  0.226  1.0
  O  O32  1  0.572  0.797  0.871  1.0
  O  O33  1  0.629  0.039  0.668  1.0
  O  O34  1  0.500  0.500  0.000  1.0
  O  O35  1  0.371  0.961  0.332  1.0
  O  O36  1  0.961  0.629  0.590  1.0
  O  O37  1  0.039  0.371  0.410  1.0
[/CIF]
.
The material structure described by Ba5Er8Zn4O21 crystallizes in the tetragonal I4/m space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 10-coordinate geometry to two equivalent O(2), four equivalent O(1), and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a distorted q6 geometry to two equivalent O(4) and eight equivalent O(2) atoms. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded to one O(4), two equivalent O(1), and four equivalent O(2) atoms to form distorted ErO7 pentagonal bipyramids that share  a cornercorner with one Er(1)O7 pentagonal bipyramid, corners with two equivalent Zn(1)O5 trigonal bipyramids, edges with two equivalent Zn(1)O5 trigonal bipyramids, and faces with two equivalent Er(1)O7 pentagonal bipyramids. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(3), two equivalent O(2), and four equivalent O(1) atoms. Zn(1) is bonded to one O(3), two equivalent O(1), and two equivalent O(2) atoms to form distorted ZnO5 trigonal bipyramids that share corners with two equivalent Er(1)O7 pentagonal bipyramids and edges with two equivalent Er(1)O7 pentagonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Er(1), two equivalent Er(2), and one Zn(1) atom. In the second O site, O(2) is bonded to one Ba(1), one Ba(2), one Er(2), two equivalent Er(1), and one Zn(1) atom to form distorted OBa2Er3Zn octahedra that share  a cornercorner with one O(4)Ba2Er4 octahedra, corners with three equivalent O(3)Ba4ErZn octahedra, corners with six equivalent O(2)Ba2Er3Zn octahedra, edges with two equivalent O(2)Ba2Er3Zn octahedra,  a faceface with one O(4)Ba2Er4 octahedra,  a faceface with one O(3)Ba4ErZn octahedra, and faces with two equivalent O(2)Ba2Er3Zn octahedra. The corner-sharing octahedral tilt angles range from 0-76°. In the third O site, O(3) is bonded to four equivalent Ba(1), one Er(2), and one Zn(1) atom to form distorted OBa4ErZn octahedra that share corners with two equivalent O(3)Ba4ErZn octahedra, corners with six equivalent O(2)Ba2Er3Zn octahedra, edges with five equivalent O(3)Ba4ErZn octahedra, and faces with two equivalent O(2)Ba2Er3Zn octahedra. The corner-sharing octahedral tilt angles range from 6-60°. In the fourth O site, O(4) is bonded to two equivalent Ba(2) and four equivalent Er(1) atoms to form OBa2Er4 octahedra that share corners with two equivalent O(4)Ba2Er4 octahedra, corners with eight equivalent O(2)Ba2Er3Zn octahedra, and faces with eight equivalent O(2)Ba2Er3Zn octahedra. The corner-sharing octahedral tilt angles range from 0-61°. is represented by the CIF file [CIF]
data_Ba5Er8Zn4O21
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.176
_cell_length_b   10.176
_cell_length_c   10.176
_cell_angle_alpha   94.535
_cell_angle_beta   94.535
_cell_angle_gamma   147.339
_symmetry_Int_Tables_number   1
_cell_volume   545.729
_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
  Ba  Ba0  1  0.535  0.860  0.396  1.0
  Ba  Ba1  1  0.860  0.465  0.325  1.0
  Ba  Ba2  1  0.140  0.535  0.675  1.0
  Ba  Ba3  1  0.465  0.140  0.604  1.0
  Ba  Ba4  1  0.000  0.000  0.000  1.0
  Er  Er5  1  0.411  0.642  0.053  1.0
  Er  Er6  1  0.642  0.589  0.230  1.0
  Er  Er7  1  0.358  0.411  0.770  1.0
  Er  Er8  1  0.589  0.358  0.947  1.0
  Er  Er9  1  0.248  0.832  0.079  1.0
  Er  Er10  1  0.832  0.752  0.584  1.0
  Er  Er11  1  0.168  0.248  0.416  1.0
  Er  Er12  1  0.752  0.168  0.921  1.0
  Zn  Zn13  1  0.041  0.750  0.791  1.0
  Zn  Zn14  1  0.750  0.959  0.709  1.0
  Zn  Zn15  1  0.250  0.041  0.291  1.0
  Zn  Zn16  1  0.959  0.250  0.209  1.0
  O  O17  1  0.900  0.494  0.892  1.0
  O  O18  1  0.494  0.602  0.595  1.0
  O  O19  1  0.007  0.900  0.405  1.0
  O  O20  1  0.602  0.007  0.108  1.0
  O  O21  1  0.100  0.506  0.108  1.0
  O  O22  1  0.506  0.398  0.405  1.0
  O  O23  1  0.993  0.100  0.595  1.0
  O  O24  1  0.398  0.993  0.892  1.0
  O  O25  1  0.073  0.299  0.871  1.0
  O  O26  1  0.299  0.428  0.226  1.0
  O  O27  1  0.203  0.073  0.774  1.0
  O  O28  1  0.428  0.203  0.129  1.0
  O  O29  1  0.927  0.701  0.129  1.0
  O  O30  1  0.701  0.572  0.774  1.0
  O  O31  1  0.797  0.927  0.226  1.0
  O  O32  1  0.572  0.797  0.871  1.0
  O  O33  1  0.629  0.039  0.668  1.0
  O  O34  1  0.500  0.500  0.000  1.0
  O  O35  1  0.371  0.961  0.332  1.0
  O  O36  1  0.961  0.629  0.590  1.0
  O  O37  1  0.039  0.371  0.410  1.0
[/CIF]
.