The crystal structure described by Li2Sr2NiO4 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with two equivalent Ni(1)O4 tetrahedra, corners with three equivalent Li(2)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form LiO4 tetrahedra that share corners with two equivalent Ni(1)O4 tetrahedra, corners with three equivalent Li(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O4 tetrahedra. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(1), and four equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded in a 6-coordinate geometry to one O(1), one 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), and one O(4) atom to form distorted NiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Li(1), one Li(2), one Sr(2), two equivalent Sr(1), and one Ni(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Sr(2), four equivalent Sr(1), and one Ni(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Li(2), two equivalent Li(1), two equivalent Sr(2), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a 7-coordinate geometry to one Li(1), two equivalent Li(2), one Sr(1), two equivalent Sr(2), and one Ni(1) atom. is represented by the CIF file [CIF]
data_Sr2Li2NiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.460
_cell_length_b   5.624
_cell_length_c   8.340
_cell_angle_alpha   106.300
_cell_angle_beta   95.778
_cell_angle_gamma   98.650
_symmetry_Int_Tables_number   1
_cell_volume   240.241
_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
  Li  Li0  1  0.801  0.380  0.455  1.0
  Li  Li1  1  0.199  0.620  0.545  1.0
  Li  Li2  1  0.414  0.114  0.412  1.0
  Li  Li3  1  0.586  0.886  0.588  1.0
  Ni  Ni4  1  0.291  0.385  0.245  1.0
  Ni  Ni5  1  0.709  0.615  0.755  1.0
  O  O6  1  0.579  0.197  0.238  1.0
  O  O7  1  0.421  0.803  0.762  1.0
  O  O8  1  0.199  0.307  0.996  1.0
  O  O9  1  0.801  0.693  0.004  1.0
  O  O10  1  0.124  0.263  0.425  1.0
  O  O11  1  0.876  0.737  0.575  1.0
  O  O12  1  0.346  0.755  0.356  1.0
  O  O13  1  0.654  0.245  0.644  1.0
  Sr  Sr14  1  0.278  0.773  0.027  1.0
  Sr  Sr15  1  0.722  0.227  0.973  1.0
  Sr  Sr16  1  0.827  0.857  0.305  1.0
  Sr  Sr17  1  0.173  0.143  0.695  1.0
[/CIF]
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The crystal structure described by Li2Sr2NiO4 crystallizes in the triclinic P-1 space group. There are two inequivalent Li sites. In the first Li site, Li(1) is bonded to one O(1), one O(4), and two equivalent O(3) atoms to form LiO4 tetrahedra that share corners with two equivalent Ni(1)O4 tetrahedra, corners with three equivalent Li(2)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O4 tetrahedra. In the second Li site, Li(2) is bonded to one O(1), one O(3), and two equivalent O(4) atoms to form LiO4 tetrahedra that share corners with two equivalent Ni(1)O4 tetrahedra, corners with three equivalent Li(1)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra,  an edgeedge with one Li(2)O4 tetrahedra, and  an edgeedge with one Ni(1)O4 tetrahedra. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(1), and four equivalent O(2) atoms. In the second Sr site, Sr(2) is bonded in a 6-coordinate geometry to one O(1), one 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), and one O(4) atom to form distorted NiO4 tetrahedra that share corners with two equivalent Li(1)O4 tetrahedra, corners with two equivalent Li(2)O4 tetrahedra,  an edgeedge with one Li(1)O4 tetrahedra, and  an edgeedge with one Li(2)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to one Li(1), one Li(2), one Sr(2), two equivalent Sr(1), and one Ni(1) atom. In the second O site, O(2) is bonded in a 6-coordinate geometry to one Sr(2), four equivalent Sr(1), and one Ni(1) atom. In the third O site, O(3) is bonded in a 6-coordinate geometry to one Li(2), two equivalent Li(1), two equivalent Sr(2), and one Ni(1) atom. In the fourth O site, O(4) is bonded in a 7-coordinate geometry to one Li(1), two equivalent Li(2), one Sr(1), two equivalent Sr(2), and one Ni(1) atom. is represented by the CIF file [CIF]
data_Sr2Li2NiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.460
_cell_length_b   5.624
_cell_length_c   8.340
_cell_angle_alpha   106.300
_cell_angle_beta   95.778
_cell_angle_gamma   98.650
_symmetry_Int_Tables_number   1
_cell_volume   240.241
_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
  Li  Li0  1  0.801  0.380  0.455  1.0
  Li  Li1  1  0.199  0.620  0.545  1.0
  Li  Li2  1  0.414  0.114  0.412  1.0
  Li  Li3  1  0.586  0.886  0.588  1.0
  Ni  Ni4  1  0.291  0.385  0.245  1.0
  Ni  Ni5  1  0.709  0.615  0.755  1.0
  O  O6  1  0.579  0.197  0.238  1.0
  O  O7  1  0.421  0.803  0.762  1.0
  O  O8  1  0.199  0.307  0.996  1.0
  O  O9  1  0.801  0.693  0.004  1.0
  O  O10  1  0.124  0.263  0.425  1.0
  O  O11  1  0.876  0.737  0.575  1.0
  O  O12  1  0.346  0.755  0.356  1.0
  O  O13  1  0.654  0.245  0.644  1.0
  Sr  Sr14  1  0.278  0.773  0.027  1.0
  Sr  Sr15  1  0.722  0.227  0.973  1.0
  Sr  Sr16  1  0.827  0.857  0.305  1.0
  Sr  Sr17  1  0.173  0.143  0.695  1.0
[/CIF]
.