The crystal structure described by Er2NiAs2 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 9-coordinate geometry to three equivalent Ni(1), three equivalent As(1), and three equivalent As(2) atoms. In the second Er site, Er(2) is bonded in a 9-coordinate geometry to three equivalent Ni(1), three equivalent As(1), and three equivalent As(2) atoms. Ni(1) is bonded in a 9-coordinate geometry to three equivalent Er(1), three equivalent Er(2), and three equivalent As(1) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to three equivalent Er(1), three equivalent Er(2), and three equivalent Ni(1) atoms. In the second As site, As(2) is bonded to three equivalent Er(1) and three equivalent Er(2) atoms to form edge-sharing AsEr6 octahedra. is represented by the CIF file [CIF]
data_Er2NiAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.103
_cell_length_b   4.103
_cell_length_c   14.031
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   204.557
_cell_formula_units_Z   2
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  0.667  0.333  0.618  1.0
  Er  Er1  1  0.333  0.667  0.118  1.0
  Er  Er2  1  0.667  0.333  0.352  1.0
  Er  Er3  1  0.333  0.667  0.852  1.0
  Ni  Ni4  1  0.000  0.000  0.998  1.0
  Ni  Ni5  1  0.000  0.000  0.498  1.0
  As  As6  1  0.667  0.333  0.983  1.0
  As  As7  1  0.333  0.667  0.483  1.0
  As  As8  1  0.000  0.000  0.733  1.0
  As  As9  1  0.000  0.000  0.233  1.0
[/CIF]
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The crystal structure described by Er2NiAs2 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 9-coordinate geometry to three equivalent Ni(1), three equivalent As(1), and three equivalent As(2) atoms. In the second Er site, Er(2) is bonded in a 9-coordinate geometry to three equivalent Ni(1), three equivalent As(1), and three equivalent As(2) atoms. Ni(1) is bonded in a 9-coordinate geometry to three equivalent Er(1), three equivalent Er(2), and three equivalent As(1) atoms. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 9-coordinate geometry to three equivalent Er(1), three equivalent Er(2), and three equivalent Ni(1) atoms. In the second As site, As(2) is bonded to three equivalent Er(1) and three equivalent Er(2) atoms to form edge-sharing AsEr6 octahedra. is represented by the CIF file [CIF]
data_Er2NiAs2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.103
_cell_length_b   4.103
_cell_length_c   14.031
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   204.557
_cell_formula_units_Z   2
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  0.667  0.333  0.618  1.0
  Er  Er1  1  0.333  0.667  0.118  1.0
  Er  Er2  1  0.667  0.333  0.352  1.0
  Er  Er3  1  0.333  0.667  0.852  1.0
  Ni  Ni4  1  0.000  0.000  0.998  1.0
  Ni  Ni5  1  0.000  0.000  0.498  1.0
  As  As6  1  0.667  0.333  0.983  1.0
  As  As7  1  0.333  0.667  0.483  1.0
  As  As8  1  0.000  0.000  0.733  1.0
  As  As9  1  0.000  0.000  0.233  1.0
[/CIF]
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