data_Ca3Ni
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.22
_cell_length_b   6.22
_cell_length_c   6.22
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca3Ni
_chemical_formula_sum   'Ca6 Ni2'
_cell_volume   241.02
_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
  Ca  Ca0  1  0.56  0.0  0.11  1.0
  Ca  Ca1  1  0.67  0.0  0.11  1.0
  Ca  Ca2  1  0.11  0.56  0.0  1.0
  Ca  Ca3  1  0.11  0.67  0.0  1.0
  Ca  Ca4  1  0.0  0.11  0.67  1.0
  Ca  Ca5  1  0.0  0.11  0.56  1.0
  Ni  Ni6  1  0.11  0.11  0.11  1.0
  Ni  Ni7  1  0.0  0.0  0.0  1.0

data_Ca3Ni
_symmetry_space_group_name_H-M   R3
_cell_length_a   8.8
_cell_length_b   8.8
_cell_length_c   10.78
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   146
_chemical_formula_structural   Ca3Ni
_chemical_formula_sum   'Ca18 Ni6'
_cell_volume   723.05
_cell_formula_units_Z   6
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  '-y, x-y, z'
  3  '-x+y, -x, z'
  4  'x+1/3, y+2/3, z+2/3'
  5  '-y+1/3, x-y+2/3, z+2/3'
  6  '-x+y+1/3, -x+2/3, z+2/3'
  7  'x+2/3, y+1/3, z+1/3'
  8  '-y+2/3, x-y+1/3, z+1/3'
  9  '-x+y+2/3, -x+1/3, z+1/3'
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
  Ca  Ca0  9  0.07  0.26  0.93  1.0
  Ca  Ca1  9  0.11  0.33  0.89  1.0
  Ni  Ni2  3  0.0  0.0  0.0  1.0
  Ni  Ni3  3  0.0  0.0  0.11  1.0

Ca Ca Ca Ca Ca Ca Ni Ni
Ca3Ni crystallizes in the trigonal R3 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted linear geometry to one Ca(2) and one Ni(1) atom. The Ca(1)-Ca(2) bond length is 0.69 Å. The Ca(1)-Ni(1) bond length is 2.85 Å. In the second Ca site, Ca(2) is bonded in a distorted single-bond geometry to one Ca(1) and one Ni(2) atom. The Ca(2)-Ni(2) bond length is 2.18 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a distorted tetrahedral geometry to three equivalent Ca(1) and one Ni(2) atom. The Ni(1)-Ni(2) bond length is 1.20 Å. In the second Ni site, Ni(2) is bonded in a tetrahedral geometry to three equivalent Ca(2) and one Ni(1) atom.