data_SrAlNi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.92
_cell_length_b   4.92
_cell_length_c   4.92
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SrAlNi
_chemical_formula_sum   'Sr1 Al1 Ni1'
_cell_volume   84.2
_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
  Sr  Sr2  1  0.74  0.74  0.74  1.0
  Al  Al0  1  0.0  0.0  0.0  1.0
  Ni  Ni1  1  0.48  0.48  0.48  1.0

data_SrAlNi
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.92
_cell_length_b   4.92
_cell_length_c   12.05
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   SrAlNi
_chemical_formula_sum   'Sr3 Al3 Ni3'
_cell_volume   252.6
_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
  Sr  Sr0  3  0.0  0.0  0.26  1.0
  Al  Al1  3  0.0  0.0  0.0  1.0
  Ni  Ni2  3  0.0  0.0  0.52  1.0

Sr Al Ni
SrNiAl is half-Heusler structured and crystallizes in the trigonal R3m space group. Sr(1) is bonded in a body-centered cubic geometry to four equivalent Ni(1) and four equivalent Al(1) atoms. There are three shorter (2.97 Å) and one longer (3.14 Å) Sr(1)-Ni(1) bond length. There are three shorter (2.97 Å) and one longer (3.14 Å) Sr(1)-Al(1) bond length. Ni(1) is bonded to four equivalent Sr(1) atoms to form NiSr4 tetrahedra that share corners with four equivalent Al(1)Sr4 tetrahedra, corners with twelve equivalent Ni(1)Sr4 tetrahedra, and edges with six equivalent Al(1)Sr4 tetrahedra. Al(1) is bonded to four equivalent Sr(1) atoms to form AlSr4 tetrahedra that share corners with four equivalent Ni(1)Sr4 tetrahedra, corners with twelve equivalent Al(1)Sr4 tetrahedra, and edges with six equivalent Ni(1)Sr4 tetrahedra.