The crystal structure described by YNiO3 crystallizes in the hexagonal P6_3cm space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(1), three equivalent O(3), and three equivalent O(4) atoms. In the second Y site, Y(2) is bonded to one O(2), three equivalent O(3), and three equivalent O(4) atoms to form distorted YO7 pentagonal bipyramids that share corners with three equivalent Ni(1)O5 trigonal bipyramids and edges with three equivalent Ni(1)O5 trigonal bipyramids. Ni(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form NiO5 trigonal bipyramids that share  a cornercorner with one Y(2)O7 pentagonal bipyramid, corners with six equivalent Ni(1)O5 trigonal bipyramids, and  an edgeedge with one Y(2)O7 pentagonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Y(1) and three equivalent Ni(1) atoms to form OYNi3 trigonal pyramids that share corners with six equivalent O(3)Y3Ni tetrahedra, corners with three equivalent O(1)YNi3 trigonal pyramids, corners with three equivalent O(2)YNi3 trigonal pyramids, and edges with three equivalent O(4)Y3Ni tetrahedra. In the second O site, O(2) is bonded to one Y(2) and three equivalent Ni(1) atoms to form OYNi3 trigonal pyramids that share corners with six equivalent O(4)Y3Ni tetrahedra, corners with six equivalent O(1)YNi3 trigonal pyramids, and edges with three equivalent O(3)Y3Ni tetrahedra. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Ni(1) atom to form distorted OY3Ni tetrahedra that share corners with four equivalent O(4)Y3Ni tetrahedra, corners with six equivalent O(3)Y3Ni tetrahedra, corners with four equivalent O(1)YNi3 trigonal pyramids, edges with three equivalent O(4)Y3Ni tetrahedra, and  an edgeedge with one O(2)YNi3 trigonal pyramid. In the fourth O site, O(4) is bonded to one Y(2), two equivalent Y(1), and one Ni(1) atom to form OY3Ni tetrahedra that share corners with four equivalent O(3)Y3Ni tetrahedra, corners with six equivalent O(4)Y3Ni tetrahedra, corners with two equivalent O(2)YNi3 trigonal pyramids, edges with three equivalent O(3)Y3Ni tetrahedra, and edges with two equivalent O(1)YNi3 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_YNiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.181
_cell_length_b   6.181
_cell_length_c   11.360
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   375.840
_cell_formula_units_Z   6
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
  Y  Y0  1  0.667  0.333  0.233  1.0
  Y  Y1  1  0.333  0.667  0.733  1.0
  Y  Y2  1  0.667  0.333  0.733  1.0
  Y  Y3  1  0.333  0.667  0.233  1.0
  Y  Y4  1  0.000  0.000  0.777  1.0
  Y  Y5  1  0.000  0.000  0.277  1.0
  Ni  Ni6  1  0.667  0.000  0.501  1.0
  Ni  Ni7  1  0.667  0.667  0.001  1.0
  Ni  Ni8  1  0.000  0.333  0.001  1.0
  Ni  Ni9  1  0.000  0.667  0.501  1.0
  Ni  Ni10  1  0.333  0.333  0.501  1.0
  Ni  Ni11  1  0.333  0.000  0.001  1.0
  O  O12  1  0.667  0.333  0.019  1.0
  O  O13  1  0.333  0.667  0.519  1.0
  O  O14  1  0.667  0.333  0.519  1.0
  O  O15  1  0.333  0.667  0.019  1.0
  O  O16  1  0.000  0.000  0.980  1.0
  O  O17  1  0.000  0.000  0.480  1.0
  O  O18  1  0.357  0.000  0.838  1.0
  O  O19  1  0.357  0.357  0.338  1.0
  O  O20  1  0.000  0.643  0.338  1.0
  O  O21  1  0.000  0.357  0.838  1.0
  O  O22  1  0.643  0.643  0.838  1.0
  O  O23  1  0.643  0.000  0.338  1.0
  O  O24  1  0.309  0.000  0.165  1.0
  O  O25  1  0.309  0.309  0.665  1.0
  O  O26  1  0.000  0.691  0.665  1.0
  O  O27  1  0.000  0.309  0.165  1.0
  O  O28  1  0.691  0.691  0.165  1.0
  O  O29  1  0.691  0.000  0.665  1.0
[/CIF]
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The crystal structure described by YNiO3 crystallizes in the hexagonal P6_3cm space group. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 7-coordinate geometry to one O(1), three equivalent O(3), and three equivalent O(4) atoms. In the second Y site, Y(2) is bonded to one O(2), three equivalent O(3), and three equivalent O(4) atoms to form distorted YO7 pentagonal bipyramids that share corners with three equivalent Ni(1)O5 trigonal bipyramids and edges with three equivalent Ni(1)O5 trigonal bipyramids. Ni(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(1) atoms to form NiO5 trigonal bipyramids that share  a cornercorner with one Y(2)O7 pentagonal bipyramid, corners with six equivalent Ni(1)O5 trigonal bipyramids, and  an edgeedge with one Y(2)O7 pentagonal bipyramid. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Y(1) and three equivalent Ni(1) atoms to form OYNi3 trigonal pyramids that share corners with six equivalent O(3)Y3Ni tetrahedra, corners with three equivalent O(1)YNi3 trigonal pyramids, corners with three equivalent O(2)YNi3 trigonal pyramids, and edges with three equivalent O(4)Y3Ni tetrahedra. In the second O site, O(2) is bonded to one Y(2) and three equivalent Ni(1) atoms to form OYNi3 trigonal pyramids that share corners with six equivalent O(4)Y3Ni tetrahedra, corners with six equivalent O(1)YNi3 trigonal pyramids, and edges with three equivalent O(3)Y3Ni tetrahedra. In the third O site, O(3) is bonded to one Y(2), two equivalent Y(1), and one Ni(1) atom to form distorted OY3Ni tetrahedra that share corners with four equivalent O(4)Y3Ni tetrahedra, corners with six equivalent O(3)Y3Ni tetrahedra, corners with four equivalent O(1)YNi3 trigonal pyramids, edges with three equivalent O(4)Y3Ni tetrahedra, and  an edgeedge with one O(2)YNi3 trigonal pyramid. In the fourth O site, O(4) is bonded to one Y(2), two equivalent Y(1), and one Ni(1) atom to form OY3Ni tetrahedra that share corners with four equivalent O(3)Y3Ni tetrahedra, corners with six equivalent O(4)Y3Ni tetrahedra, corners with two equivalent O(2)YNi3 trigonal pyramids, edges with three equivalent O(3)Y3Ni tetrahedra, and edges with two equivalent O(1)YNi3 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_YNiO3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.181
_cell_length_b   6.181
_cell_length_c   11.360
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   375.840
_cell_formula_units_Z   6
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
  Y  Y0  1  0.667  0.333  0.233  1.0
  Y  Y1  1  0.333  0.667  0.733  1.0
  Y  Y2  1  0.667  0.333  0.733  1.0
  Y  Y3  1  0.333  0.667  0.233  1.0
  Y  Y4  1  0.000  0.000  0.777  1.0
  Y  Y5  1  0.000  0.000  0.277  1.0
  Ni  Ni6  1  0.667  0.000  0.501  1.0
  Ni  Ni7  1  0.667  0.667  0.001  1.0
  Ni  Ni8  1  0.000  0.333  0.001  1.0
  Ni  Ni9  1  0.000  0.667  0.501  1.0
  Ni  Ni10  1  0.333  0.333  0.501  1.0
  Ni  Ni11  1  0.333  0.000  0.001  1.0
  O  O12  1  0.667  0.333  0.019  1.0
  O  O13  1  0.333  0.667  0.519  1.0
  O  O14  1  0.667  0.333  0.519  1.0
  O  O15  1  0.333  0.667  0.019  1.0
  O  O16  1  0.000  0.000  0.980  1.0
  O  O17  1  0.000  0.000  0.480  1.0
  O  O18  1  0.357  0.000  0.838  1.0
  O  O19  1  0.357  0.357  0.338  1.0
  O  O20  1  0.000  0.643  0.338  1.0
  O  O21  1  0.000  0.357  0.838  1.0
  O  O22  1  0.643  0.643  0.838  1.0
  O  O23  1  0.643  0.000  0.338  1.0
  O  O24  1  0.309  0.000  0.165  1.0
  O  O25  1  0.309  0.309  0.665  1.0
  O  O26  1  0.000  0.691  0.665  1.0
  O  O27  1  0.000  0.309  0.165  1.0
  O  O28  1  0.691  0.691  0.165  1.0
  O  O29  1  0.691  0.000  0.665  1.0
[/CIF]
.