data_FeCuNi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.88
_cell_length_b   3.88
_cell_length_c   3.88
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   FeCuNi
_chemical_formula_sum   'Fe1 Cu1 Ni1'
_cell_volume   41.16
_cell_formula_units_Z   1
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
  Fe  Fe1  1  0.0  0.0  0.0  1.0
  Cu  Cu0  1  0.74  0.74  0.74  1.0
  Ni  Ni2  1  0.37  0.37  0.37  1.0

data_FeCuNi
_symmetry_space_group_name_H-M   R3m
_cell_length_a   3.88
_cell_length_b   3.88
_cell_length_c   9.49
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   FeCuNi
_chemical_formula_sum   'Fe3 Cu3 Ni3'
_cell_volume   123.47
_cell_formula_units_Z   3
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  '-y, -x, z'
  5  '-x+y, y, z'
  6  'x, x-y, z'
  7  'x+1/3, y+2/3, z+2/3'
  8  '-y+1/3, x-y+2/3, z+2/3'
  9  '-x+y+1/3, -x+2/3, z+2/3'
  10  '-y+1/3, -x+2/3, z+2/3'
  11  '-x+y+1/3, y+2/3, z+2/3'
  12  'x+1/3, x-y+2/3, z+2/3'
  13  'x+2/3, y+1/3, z+1/3'
  14  '-y+2/3, x-y+1/3, z+1/3'
  15  '-x+y+2/3, -x+1/3, z+1/3'
  16  '-y+2/3, -x+1/3, z+1/3'
  17  '-x+y+2/3, y+1/3, z+1/3'
  18  'x+2/3, x-y+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
  Fe  Fe0  3  0.0  0.0  0.0  1.0
  Cu  Cu1  3  0.0  0.0  0.26  1.0
  Ni  Ni2  3  0.0  0.0  0.63  1.0

Fe Cu Ni
Fe Cu Ni 0 1 - - - 0 1 - - o 0 1 - o - 0 1 o - - 0 2 - o o 0 2 o - o 0 2 o o - 1 2 o o + 1 2 o + o 1 2 + o o 
FeNiCu crystallizes in the trigonal R3m space group. Fe(1) is bonded to three equivalent Ni(1) and four equivalent Cu(1) atoms to form distorted FeCu4Ni3 hexagonal pyramids that share corners with three equivalent Cu(1)Fe4Ni3 hexagonal pyramids, corners with six equivalent Fe(1)Cu4Ni3 hexagonal pyramids, edges with three equivalent Cu(1)Fe4Ni3 hexagonal pyramids, and edges with six equivalent Fe(1)Cu4Ni3 hexagonal pyramids. All Fe(1)-Ni(1) bond lengths are 2.26 Å. There are three shorter (2.34 Å) and one longer (2.47 Å) Fe(1)-Cu(1) bond length. Ni(1) is bonded in a hexagonal planar geometry to three equivalent Fe(1) and three equivalent Cu(1) atoms. All Ni(1)-Cu(1) bond lengths are 2.26 Å. Cu(1) is bonded to four equivalent Fe(1) and three equivalent Ni(1) atoms to form distorted CuFe4Ni3 hexagonal pyramids that share corners with three equivalent Fe(1)Cu4Ni3 hexagonal pyramids, corners with six equivalent Cu(1)Fe4Ni3 hexagonal pyramids, edges with three equivalent Fe(1)Cu4Ni3 hexagonal pyramids, and edges with six equivalent Cu(1)Fe4Ni3 hexagonal pyramids.