The crystal structure described by NiAl2O4 is Spinel structured and crystallizes in the triclinic P1 space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form NiO4 tetrahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Al(2)O6 octahedra, corners with three equivalent Al(3)O6 octahedra, and corners with three equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-62°. In the second Ni site, Ni(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form NiO4 tetrahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Al(2)O6 octahedra, corners with three equivalent Al(3)O6 octahedra, and corners with three equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-62°. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(2)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the second Al site, Al(2) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(8) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ni(2), one Al(1), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni tetrahedra. In the second O site, O(2) is bonded to one Ni(1), one Al(1), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the third O site, O(3) is bonded to one Ni(2), one Al(2), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the fourth O site, O(4) is bonded to one Ni(1), one Al(2), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni tetrahedra. In the fifth O site, O(5) is bonded to one Ni(2), one Al(1), one Al(2), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the sixth O site, O(6) is bonded to one Ni(2), one Al(1), one Al(2), and one Al(3) atom to form a mixture of distorted corner and edge-sharing OAl3Ni tetrahedra. In the seventh O site, O(7) is bonded to one Ni(1), one Al(1), one Al(2), and one Al(3) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the eighth O site, O(8) is bonded to one Ni(1), one Al(1), one Al(2), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. is represented by the CIF file [CIF]
data_Al2NiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.756
_cell_length_b   5.783
_cell_length_c   5.754
_cell_angle_alpha   60.400
_cell_angle_beta   60.600
_cell_angle_gamma   60.037
_symmetry_Int_Tables_number   1
_cell_volume   136.498
_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
  Al  Al0  1  0.500  0.002  0.500  1.0
  Al  Al1  1  0.999  0.500  0.501  1.0
  Al  Al2  1  0.500  0.499  0.500  1.0
  Al  Al3  1  0.501  0.500  0.999  1.0
  Ni  Ni4  1  0.130  0.119  0.125  1.0
  Ni  Ni5  1  0.879  0.871  0.880  1.0
  O  O6  1  0.295  0.740  0.729  1.0
  O  O7  1  0.709  0.264  0.263  1.0
  O  O8  1  0.737  0.291  0.736  1.0
  O  O9  1  0.262  0.702  0.266  1.0
  O  O10  1  0.735  0.738  0.738  1.0
  O  O11  1  0.729  0.737  0.296  1.0
  O  O12  1  0.263  0.268  0.707  1.0
  O  O13  1  0.262  0.270  0.260  1.0
[/CIF]
.
The crystal structure described by NiAl2O4 is Spinel structured and crystallizes in the triclinic P1 space group. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(4), one O(7), and one O(8) atom to form NiO4 tetrahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Al(2)O6 octahedra, corners with three equivalent Al(3)O6 octahedra, and corners with three equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-62°. In the second Ni site, Ni(2) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form NiO4 tetrahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Al(2)O6 octahedra, corners with three equivalent Al(3)O6 octahedra, and corners with three equivalent Al(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 58-62°. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(2)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the second Al site, Al(2) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(3)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the third Al site, Al(3) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(7) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(4)O6 octahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(8) atom to form AlO6 octahedra that share corners with three equivalent Ni(1)O4 tetrahedra, corners with three equivalent Ni(2)O4 tetrahedra, edges with two equivalent Al(1)O6 octahedra, edges with two equivalent Al(2)O6 octahedra, and edges with two equivalent Al(3)O6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ni(2), one Al(1), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni tetrahedra. In the second O site, O(2) is bonded to one Ni(1), one Al(1), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the third O site, O(3) is bonded to one Ni(2), one Al(2), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the fourth O site, O(4) is bonded to one Ni(1), one Al(2), one Al(3), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni tetrahedra. In the fifth O site, O(5) is bonded to one Ni(2), one Al(1), one Al(2), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the sixth O site, O(6) is bonded to one Ni(2), one Al(1), one Al(2), and one Al(3) atom to form a mixture of distorted corner and edge-sharing OAl3Ni tetrahedra. In the seventh O site, O(7) is bonded to one Ni(1), one Al(1), one Al(2), and one Al(3) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. In the eighth O site, O(8) is bonded to one Ni(1), one Al(1), one Al(2), and one Al(4) atom to form a mixture of distorted corner and edge-sharing OAl3Ni trigonal pyramids. is represented by the CIF file [CIF]
data_Al2NiO4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.756
_cell_length_b   5.783
_cell_length_c   5.754
_cell_angle_alpha   60.400
_cell_angle_beta   60.600
_cell_angle_gamma   60.037
_symmetry_Int_Tables_number   1
_cell_volume   136.498
_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
  Al  Al0  1  0.500  0.002  0.500  1.0
  Al  Al1  1  0.999  0.500  0.501  1.0
  Al  Al2  1  0.500  0.499  0.500  1.0
  Al  Al3  1  0.501  0.500  0.999  1.0
  Ni  Ni4  1  0.130  0.119  0.125  1.0
  Ni  Ni5  1  0.879  0.871  0.880  1.0
  O  O6  1  0.295  0.740  0.729  1.0
  O  O7  1  0.709  0.264  0.263  1.0
  O  O8  1  0.737  0.291  0.736  1.0
  O  O9  1  0.262  0.702  0.266  1.0
  O  O10  1  0.735  0.738  0.738  1.0
  O  O11  1  0.729  0.737  0.296  1.0
  O  O12  1  0.263  0.268  0.707  1.0
  O  O13  1  0.262  0.270  0.260  1.0
[/CIF]
.