The compound described by Ba2CaEr3(NiO5)2 crystallizes in the monoclinic C2 space group. Ba(1) is bonded in a distorted q6 geometry to one O(5), one O(6), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Ca(1) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the third Er site, Er(3) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), one Ca(1), one Er(1), one Er(2), and one Ni(1) atom to form distorted OBa2CaEr2Ni octahedra that share  a cornercorner with one O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with two equivalent O(5)Ba2CaErNi2 octahedra, corners with seven equivalent O(4)Ba2Er3Ni octahedra,  an edgeedge with one O(4)Ba2Er3Ni octahedra, edges with two equivalent O(2)Ba2CaEr2Ni octahedra, edges with two equivalent O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(1)Ba2CaEr2Ni octahedra,  a faceface with one O(2)Ba2CaEr2Ni octahedra,  a faceface with one O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra, and  a faceface with one O(6)Ba2Er2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 2-69°. In the second O site, O(2) is bonded to two equivalent Ba(1), one Ca(1), one Er(1), one Er(3), and one Ni(1) atom to form distorted OBa2CaEr2Ni octahedra that share  a cornercorner with one O(5)Ba2CaErNi2 octahedra, corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with seven equivalent O(3)Ba2CaEr2Ni octahedra,  an edgeedge with one O(3)Ba2CaEr2Ni octahedra, edges with two equivalent O(1)Ba2CaEr2Ni octahedra, edges with two equivalent O(4)Ba2Er3Ni octahedra,  a faceface with one O(1)Ba2CaEr2Ni octahedra,  a faceface with one O(2)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra,  a faceface with one O(6)Ba2Er2Ni2 octahedra, and  a faceface with one O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 2-69°. In the third O site, O(3) is bonded to two equivalent Ba(1), one Ca(1), one Er(2), one Er(3), and one Ni(1) atom to form distorted OBa2CaEr2Ni octahedra that share  a cornercorner with one O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with two equivalent O(5)Ba2CaErNi2 octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with seven equivalent O(2)Ba2CaEr2Ni octahedra,  an edgeedge with one O(2)Ba2CaEr2Ni octahedra, edges with two equivalent O(1)Ba2CaEr2Ni octahedra, edges with two equivalent O(4)Ba2Er3Ni octahedra,  a faceface with one O(1)Ba2CaEr2Ni octahedra,  a faceface with one O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra,  a faceface with one O(6)Ba2Er2Ni2 octahedra, and  a faceface with one O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 2-68°. In the fourth O site, O(4) is bonded to two equivalent Ba(1), one Er(1), one Er(2), one Er(3), and one Ni(1) atom to form distorted OBa2Er3Ni octahedra that share  a cornercorner with one O(5)Ba2CaErNi2 octahedra, corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with two equivalent O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with seven equivalent O(1)Ba2CaEr2Ni octahedra,  an edgeedge with one O(1)Ba2CaEr2Ni octahedra, edges with two equivalent O(2)Ba2CaEr2Ni octahedra, edges with two equivalent O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(2)Ba2CaEr2Ni octahedra,  a faceface with one O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra,  a faceface with one O(6)Ba2Er2Ni2 octahedra, and  a faceface with one O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 2-68°. In the fifth O site, O(5) is bonded to two equivalent Ba(1), one Ca(1), one Er(2), and two equivalent Ni(1) atoms to form distorted OBa2CaErNi2 octahedra that share corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with four equivalent O(1)Ba2CaEr2Ni octahedra, corners with four equivalent O(3)Ba2CaEr2Ni octahedra, corners with four equivalent O(6)Ba2Er2Ni2 octahedra, faces with two equivalent O(1)Ba2CaEr2Ni octahedra, faces with two equivalent O(2)Ba2CaEr2Ni octahedra, faces with two equivalent O(3)Ba2CaEr2Ni octahedra, and faces with two equivalent O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 1-59°. In the sixth O site, O(6) is bonded to two equivalent Ba(1), one Er(1), one Er(3), and two equivalent Ni(1) atoms to form distorted OBa2Er2Ni2 octahedra that share corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with four equivalent O(2)Ba2CaEr2Ni octahedra, corners with four equivalent O(5)Ba2CaErNi2 octahedra, corners with four equivalent O(4)Ba2Er3Ni octahedra, faces with two equivalent O(1)Ba2CaEr2Ni octahedra, faces with two equivalent O(2)Ba2CaEr2Ni octahedra, faces with two equivalent O(3)Ba2CaEr2Ni octahedra, and faces with two equivalent O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 1-60°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2CaEr3(NiO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.615
_cell_length_b   6.615
_cell_length_c   6.903
_cell_angle_alpha   102.387
_cell_angle_beta   77.613
_cell_angle_gamma   62.911
_symmetry_Int_Tables_number   1
_cell_volume   245.135
_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  0.001  1.000  0.502  1.0
  Ba  Ba1  1  0.500  0.501  0.998  1.0
  Ca  Ca2  1  0.043  0.543  0.750  1.0
  Er  Er3  1  0.545  0.045  0.250  1.0
  Er  Er4  1  0.456  0.956  0.750  1.0
  Er  Er5  1  0.956  0.456  0.250  1.0
  Ni  Ni6  1  0.998  0.998  0.999  1.0
  Ni  Ni7  1  0.498  0.498  0.501  1.0
  O  O8  1  0.723  0.984  0.889  1.0
  O  O9  1  0.243  0.466  0.370  1.0
  O  O10  1  0.757  0.529  0.612  1.0
  O  O11  1  0.267  0.029  0.121  1.0
  O  O12  1  0.029  0.257  0.888  1.0
  O  O13  1  0.529  0.767  0.379  1.0
  O  O14  1  0.484  0.223  0.611  1.0
  O  O15  1  0.966  0.743  0.130  1.0
  O  O16  1  0.253  0.753  0.750  1.0
  O  O17  1  0.751  0.251  0.250  1.0
[/CIF]
.
The compound described by Ba2CaEr3(NiO5)2 crystallizes in the monoclinic C2 space group. Ba(1) is bonded in a distorted q6 geometry to one O(5), one O(6), two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Ca(1) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. There are three inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. In the third Er site, Er(3) is bonded in a 7-coordinate geometry to one O(6), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Ni(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 2-4°. There are six inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ba(1), one Ca(1), one Er(1), one Er(2), and one Ni(1) atom to form distorted OBa2CaEr2Ni octahedra that share  a cornercorner with one O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with two equivalent O(5)Ba2CaErNi2 octahedra, corners with seven equivalent O(4)Ba2Er3Ni octahedra,  an edgeedge with one O(4)Ba2Er3Ni octahedra, edges with two equivalent O(2)Ba2CaEr2Ni octahedra, edges with two equivalent O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(1)Ba2CaEr2Ni octahedra,  a faceface with one O(2)Ba2CaEr2Ni octahedra,  a faceface with one O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra, and  a faceface with one O(6)Ba2Er2Ni2 octahedra. The corner-sharing octahedral tilt angles range from 2-69°. In the second O site, O(2) is bonded to two equivalent Ba(1), one Ca(1), one Er(1), one Er(3), and one Ni(1) atom to form distorted OBa2CaEr2Ni octahedra that share  a cornercorner with one O(5)Ba2CaErNi2 octahedra, corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with seven equivalent O(3)Ba2CaEr2Ni octahedra,  an edgeedge with one O(3)Ba2CaEr2Ni octahedra, edges with two equivalent O(1)Ba2CaEr2Ni octahedra, edges with two equivalent O(4)Ba2Er3Ni octahedra,  a faceface with one O(1)Ba2CaEr2Ni octahedra,  a faceface with one O(2)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra,  a faceface with one O(6)Ba2Er2Ni2 octahedra, and  a faceface with one O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 2-69°. In the third O site, O(3) is bonded to two equivalent Ba(1), one Ca(1), one Er(2), one Er(3), and one Ni(1) atom to form distorted OBa2CaEr2Ni octahedra that share  a cornercorner with one O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with two equivalent O(5)Ba2CaErNi2 octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with seven equivalent O(2)Ba2CaEr2Ni octahedra,  an edgeedge with one O(2)Ba2CaEr2Ni octahedra, edges with two equivalent O(1)Ba2CaEr2Ni octahedra, edges with two equivalent O(4)Ba2Er3Ni octahedra,  a faceface with one O(1)Ba2CaEr2Ni octahedra,  a faceface with one O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra,  a faceface with one O(6)Ba2Er2Ni2 octahedra, and  a faceface with one O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 2-68°. In the fourth O site, O(4) is bonded to two equivalent Ba(1), one Er(1), one Er(2), one Er(3), and one Ni(1) atom to form distorted OBa2Er3Ni octahedra that share  a cornercorner with one O(5)Ba2CaErNi2 octahedra, corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with two equivalent O(6)Ba2Er2Ni2 octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with seven equivalent O(1)Ba2CaEr2Ni octahedra,  an edgeedge with one O(1)Ba2CaEr2Ni octahedra, edges with two equivalent O(2)Ba2CaEr2Ni octahedra, edges with two equivalent O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(2)Ba2CaEr2Ni octahedra,  a faceface with one O(3)Ba2CaEr2Ni octahedra,  a faceface with one O(5)Ba2CaErNi2 octahedra,  a faceface with one O(6)Ba2Er2Ni2 octahedra, and  a faceface with one O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 2-68°. In the fifth O site, O(5) is bonded to two equivalent Ba(1), one Ca(1), one Er(2), and two equivalent Ni(1) atoms to form distorted OBa2CaErNi2 octahedra that share corners with two equivalent O(2)Ba2CaEr2Ni octahedra, corners with two equivalent O(4)Ba2Er3Ni octahedra, corners with four equivalent O(1)Ba2CaEr2Ni octahedra, corners with four equivalent O(3)Ba2CaEr2Ni octahedra, corners with four equivalent O(6)Ba2Er2Ni2 octahedra, faces with two equivalent O(1)Ba2CaEr2Ni octahedra, faces with two equivalent O(2)Ba2CaEr2Ni octahedra, faces with two equivalent O(3)Ba2CaEr2Ni octahedra, and faces with two equivalent O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 1-59°. In the sixth O site, O(6) is bonded to two equivalent Ba(1), one Er(1), one Er(3), and two equivalent Ni(1) atoms to form distorted OBa2Er2Ni2 octahedra that share corners with two equivalent O(1)Ba2CaEr2Ni octahedra, corners with two equivalent O(3)Ba2CaEr2Ni octahedra, corners with four equivalent O(2)Ba2CaEr2Ni octahedra, corners with four equivalent O(5)Ba2CaErNi2 octahedra, corners with four equivalent O(4)Ba2Er3Ni octahedra, faces with two equivalent O(1)Ba2CaEr2Ni octahedra, faces with two equivalent O(2)Ba2CaEr2Ni octahedra, faces with two equivalent O(3)Ba2CaEr2Ni octahedra, and faces with two equivalent O(4)Ba2Er3Ni octahedra. The corner-sharing octahedral tilt angles range from 1-60°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2CaEr3(NiO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.615
_cell_length_b   6.615
_cell_length_c   6.903
_cell_angle_alpha   102.387
_cell_angle_beta   77.613
_cell_angle_gamma   62.911
_symmetry_Int_Tables_number   1
_cell_volume   245.135
_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  0.001  1.000  0.502  1.0
  Ba  Ba1  1  0.500  0.501  0.998  1.0
  Ca  Ca2  1  0.043  0.543  0.750  1.0
  Er  Er3  1  0.545  0.045  0.250  1.0
  Er  Er4  1  0.456  0.956  0.750  1.0
  Er  Er5  1  0.956  0.456  0.250  1.0
  Ni  Ni6  1  0.998  0.998  0.999  1.0
  Ni  Ni7  1  0.498  0.498  0.501  1.0
  O  O8  1  0.723  0.984  0.889  1.0
  O  O9  1  0.243  0.466  0.370  1.0
  O  O10  1  0.757  0.529  0.612  1.0
  O  O11  1  0.267  0.029  0.121  1.0
  O  O12  1  0.029  0.257  0.888  1.0
  O  O13  1  0.529  0.767  0.379  1.0
  O  O14  1  0.484  0.223  0.611  1.0
  O  O15  1  0.966  0.743  0.130  1.0
  O  O16  1  0.253  0.753  0.750  1.0
  O  O17  1  0.751  0.251  0.250  1.0
[/CIF]
.