data_Sr2SiNi
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.02
_cell_length_b   5.02
_cell_length_c   5.02
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Sr2SiNi
_chemical_formula_sum   'Sr2 Si1 Ni1'
_cell_volume   89.22
_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  0.77  0.77  0.77  1.0
  Sr  Sr3  1  0.55  0.55  0.55  1.0
  Si  Si1  1  0.0  0.0  0.0  1.0
  Ni  Ni0  1  0.32  0.32  0.32  1.0

data_Sr2SiNi
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.02
_cell_length_b   5.02
_cell_length_c   12.29
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   Sr2SiNi
_chemical_formula_sum   'Sr6 Si3 Ni3'
_cell_volume   267.66
_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  0.23  1.0
  Sr  Sr1  3  0.0  0.0  0.45  1.0
  Si  Si2  3  0.0  0.0  0.0  1.0
  Ni  Ni3  3  0.0  0.0  0.68  1.0

Sr Sr Si Ni
Sr Sr Si Ni 0 2 + o + 0 2 o + + 0 2 + + o 0 2 + + + 0 1 o o o 0 1 o o + 0 1 + o o 0 1 o + o 0 3 o o + 0 3 o + o 0 3 + o o 1 3 o o o 1 3 o o + 1 3 + o o 1 3 o + o 1 2 o + + 1 2 + o + 1 2 + + o 2 3 - o o 2 3 o - o 2 3 o o - 
Sr2NiSi crystallizes in the trigonal R3m space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 1-coordinate geometry to three equivalent Ni(1) and four equivalent Si(1) atoms. All Sr(1)-Ni(1) bond lengths are 3.25 Å. There is one shorter (2.79 Å) and three longer (3.18 Å) Sr(1)-Si(1) bond lengths. In the second Sr site, Sr(2) is bonded in a 1-coordinate geometry to four equivalent Ni(1) and three equivalent Si(1) atoms. There is one shorter (2.79 Å) and three longer (3.18 Å) Sr(2)-Ni(1) bond lengths. All Sr(2)-Si(1) bond lengths are 3.25 Å. Ni(1) is bonded in a 10-coordinate geometry to three equivalent Sr(1), four equivalent Sr(2), and three equivalent Si(1) atoms. All Ni(1)-Si(1) bond lengths are 2.90 Å. Si(1) is bonded in a 10-coordinate geometry to three equivalent Sr(2), four equivalent Sr(1), and three equivalent Ni(1) atoms.