The crystal structure described by Sr2Ni2GaAlO7 crystallizes in the monoclinic Cc space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), two equivalent O(7), and four equivalent O(6) atoms. In the second Sr site, Sr(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(3) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(5) atoms to form distorted NiO5 square pyramids that share  a cornercorner with one Al(1)O6 octahedra, corners with two equivalent Ni(2)O6 square pyramids, corners with four equivalent Ni(1)O5 square pyramids, edges with two equivalent Al(1)O6 octahedra,  an edgeedge with one Ni(2)O6 square pyramid, and  a faceface with one Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the second Ni site, Ni(2) is bonded to one O(5), one O(6), two equivalent O(1), and two equivalent O(7) atoms to form distorted NiO6 square pyramids that share  a cornercorner with one Al(1)O6 octahedra, corners with two equivalent Ni(1)O5 square pyramids, corners with four equivalent Ni(2)O6 square pyramids,  a cornercorner with one Ga(1)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra,  an edgeedge with one Ni(1)O5 square pyramid, and  a faceface with one Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 58°. Ga(1) is bonded to one O(3), one O(6), and two equivalent O(2) atoms to form GaO4 tetrahedra that share  a cornercorner with one Ni(2)O6 square pyramid and corners with two equivalent Ga(1)O4 tetrahedra. Al(1) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with four equivalent Al(1)O6 octahedra,  a cornercorner with one Ni(1)O5 square pyramid,  a cornercorner with one Ni(2)O6 square pyramid, edges with two equivalent Ni(1)O5 square pyramids, edges with two equivalent Ni(2)O6 square pyramids,  a faceface with one Ni(1)O5 square pyramid, and  a faceface with one Ni(2)O6 square pyramid. The corner-sharing octahedral tilt angles range from 46-47°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a 6-coordinate geometry to four equivalent Sr(1), one Ni(2), and one Ga(1) atom. In the second O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Ni(2), and one Al(1) atom. In the third O site, O(1) is bonded in a 5-coordinate geometry to one Sr(1), one Ni(1), two equivalent Ni(2), and two equivalent Al(1) atoms. In the fourth O site, O(2) is bonded to one Sr(1), one Sr(2), and two equivalent Ga(1) atoms to form distorted corner-sharing OSr2Ga2 trigonal pyramids. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Sr(2) and one Ga(1) atom. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Ni(1), and one Al(1) atom. In the seventh O site, O(5) is bonded in a 5-coordinate geometry to one Ni(2), two equivalent Ni(1), and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_Sr2AlGaNi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.704
_cell_length_b   11.704
_cell_length_c   5.645
_cell_angle_alpha   83.537
_cell_angle_beta   83.537
_cell_angle_gamma   25.549
_symmetry_Int_Tables_number   1
_cell_volume   331.324
_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
  Sr  Sr0  1  0.845  0.350  0.253  1.0
  Sr  Sr1  1  0.155  0.640  0.746  1.0
  Sr  Sr2  1  0.350  0.845  0.753  1.0
  Sr  Sr3  1  0.640  0.155  0.246  1.0
  Al  Al4  1  0.499  0.996  0.500  1.0
  Al  Al5  1  0.996  0.499  1.000  1.0
  Ga  Ga6  1  0.301  0.690  0.207  1.0
  Ga  Ga7  1  0.690  0.301  0.707  1.0
  Ni  Ni8  1  0.072  0.536  0.365  1.0
  Ni  Ni9  1  0.458  0.922  0.137  1.0
  Ni  Ni10  1  0.536  0.072  0.865  1.0
  Ni  Ni11  1  0.922  0.458  0.637  1.0
  O  O12  1  0.282  0.154  0.826  1.0
  O  O13  1  0.365  0.622  0.875  1.0
  O  O14  1  0.154  0.282  0.326  1.0
  O  O15  1  0.724  0.114  0.809  1.0
  O  O16  1  0.415  0.222  0.529  1.0
  O  O17  1  0.222  0.415  0.029  1.0
  O  O18  1  0.622  0.365  0.375  1.0
  O  O19  1  0.712  0.841  0.177  1.0
  O  O20  1  0.841  0.712  0.677  1.0
  O  O21  1  0.114  0.724  0.309  1.0
  O  O22  1  0.284  0.865  0.211  1.0
  O  O23  1  0.865  0.284  0.711  1.0
  O  O24  1  0.771  0.581  0.972  1.0
  O  O25  1  0.581  0.771  0.472  1.0
[/CIF]
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The crystal structure described by Sr2Ni2GaAlO7 crystallizes in the monoclinic Cc space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(2), two equivalent O(7), and four equivalent O(6) atoms. In the second Sr site, Sr(2) is bonded in a 4-coordinate geometry to one O(2), one O(4), and two equivalent O(3) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(5) atoms to form distorted NiO5 square pyramids that share  a cornercorner with one Al(1)O6 octahedra, corners with two equivalent Ni(2)O6 square pyramids, corners with four equivalent Ni(1)O5 square pyramids, edges with two equivalent Al(1)O6 octahedra,  an edgeedge with one Ni(2)O6 square pyramid, and  a faceface with one Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 57°. In the second Ni site, Ni(2) is bonded to one O(5), one O(6), two equivalent O(1), and two equivalent O(7) atoms to form distorted NiO6 square pyramids that share  a cornercorner with one Al(1)O6 octahedra, corners with two equivalent Ni(1)O5 square pyramids, corners with four equivalent Ni(2)O6 square pyramids,  a cornercorner with one Ga(1)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra,  an edgeedge with one Ni(1)O5 square pyramid, and  a faceface with one Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 58°. Ga(1) is bonded to one O(3), one O(6), and two equivalent O(2) atoms to form GaO4 tetrahedra that share  a cornercorner with one Ni(2)O6 square pyramid and corners with two equivalent Ga(1)O4 tetrahedra. Al(1) is bonded to one O(4), one O(7), two equivalent O(1), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with four equivalent Al(1)O6 octahedra,  a cornercorner with one Ni(1)O5 square pyramid,  a cornercorner with one Ni(2)O6 square pyramid, edges with two equivalent Ni(1)O5 square pyramids, edges with two equivalent Ni(2)O6 square pyramids,  a faceface with one Ni(1)O5 square pyramid, and  a faceface with one Ni(2)O6 square pyramid. The corner-sharing octahedral tilt angles range from 46-47°. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a 6-coordinate geometry to four equivalent Sr(1), one Ni(2), and one Ga(1) atom. In the second O site, O(7) is bonded in a 4-coordinate geometry to two equivalent Sr(1), two equivalent Ni(2), and one Al(1) atom. In the third O site, O(1) is bonded in a 5-coordinate geometry to one Sr(1), one Ni(1), two equivalent Ni(2), and two equivalent Al(1) atoms. In the fourth O site, O(2) is bonded to one Sr(1), one Sr(2), and two equivalent Ga(1) atoms to form distorted corner-sharing OSr2Ga2 trigonal pyramids. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Sr(2) and one Ga(1) atom. In the sixth O site, O(4) is bonded in a 4-coordinate geometry to one Sr(2), two equivalent Ni(1), and one Al(1) atom. In the seventh O site, O(5) is bonded in a 5-coordinate geometry to one Ni(2), two equivalent Ni(1), and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_Sr2AlGaNi2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.704
_cell_length_b   11.704
_cell_length_c   5.645
_cell_angle_alpha   83.537
_cell_angle_beta   83.537
_cell_angle_gamma   25.549
_symmetry_Int_Tables_number   1
_cell_volume   331.324
_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
  Sr  Sr0  1  0.845  0.350  0.253  1.0
  Sr  Sr1  1  0.155  0.640  0.746  1.0
  Sr  Sr2  1  0.350  0.845  0.753  1.0
  Sr  Sr3  1  0.640  0.155  0.246  1.0
  Al  Al4  1  0.499  0.996  0.500  1.0
  Al  Al5  1  0.996  0.499  1.000  1.0
  Ga  Ga6  1  0.301  0.690  0.207  1.0
  Ga  Ga7  1  0.690  0.301  0.707  1.0
  Ni  Ni8  1  0.072  0.536  0.365  1.0
  Ni  Ni9  1  0.458  0.922  0.137  1.0
  Ni  Ni10  1  0.536  0.072  0.865  1.0
  Ni  Ni11  1  0.922  0.458  0.637  1.0
  O  O12  1  0.282  0.154  0.826  1.0
  O  O13  1  0.365  0.622  0.875  1.0
  O  O14  1  0.154  0.282  0.326  1.0
  O  O15  1  0.724  0.114  0.809  1.0
  O  O16  1  0.415  0.222  0.529  1.0
  O  O17  1  0.222  0.415  0.029  1.0
  O  O18  1  0.622  0.365  0.375  1.0
  O  O19  1  0.712  0.841  0.177  1.0
  O  O20  1  0.841  0.712  0.677  1.0
  O  O21  1  0.114  0.724  0.309  1.0
  O  O22  1  0.284  0.865  0.211  1.0
  O  O23  1  0.865  0.284  0.711  1.0
  O  O24  1  0.771  0.581  0.972  1.0
  O  O25  1  0.581  0.771  0.472  1.0
[/CIF]
.