data_SrTi2Nb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.97
_cell_length_b   4.97
_cell_length_c   4.97
_cell_angle_alpha   120.98
_cell_angle_beta   120.98
_cell_angle_gamma   88.31
_symmetry_Int_Tables_number   1
_chemical_formula_structural   SrTi2Nb
_chemical_formula_sum   'Sr1 Ti2 Nb1'
_cell_volume   85.44
_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  Sr1  1  0.0  0.0  0.0  1.0
  Ti  Ti2  1  0.45  0.0  0.78  1.0
  Ti  Ti3  1  0.0  0.45  0.78  1.0
  Nb  Nb0  1  0.0  0.0  0.57  1.0

data_SrTi2Nb
_symmetry_space_group_name_H-M   Cm
_cell_length_a   6.92
_cell_length_b   6.92
_cell_length_c   4.97
_cell_angle_alpha   90.0
_cell_angle_beta   134.15
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   8
_chemical_formula_structural   SrTi2Nb
_chemical_formula_sum   'Sr2 Ti4 Nb2'
_cell_volume   170.88
_cell_formula_units_Z   2
loop_
 _symmetry_equiv_pos_site_id
 _symmetry_equiv_pos_as_xyz
  1  'x, y, z'
  2  'x, -y, z'
  3  'x+1/2, y+1/2, z'
  4  'x+1/2, -y+1/2, 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  Sr0  2  0.0  0.0  0.0  1.0
  Ti  Ti1  4  0.28  0.28  0.34  1.0
  Nb  Nb2  2  0.0  0.0  0.57  1.0

Sr Ti Ti Nb
Sr Ti Ti Nb 0 1 - o - 0 2 o - - 0 3 o o - 1 3 o o o 2 3 o o o 
SrTi2Nb crystallizes in the monoclinic Cm space group. Sr(1) is bonded in a 4-coordinate geometry to two equivalent Ti(1) and two equivalent Nb(1) atoms. Both Sr(1)-Ti(1) bond lengths are 2.38 Å. There is one shorter (2.16 Å) and one longer (2.81 Å) Sr(1)-Nb(1) bond length. Ti(1) is bonded in a distorted linear geometry to one Sr(1) and one Nb(1) atom. The Ti(1)-Nb(1) bond length is 1.91 Å. Nb(1) is bonded in a distorted see-saw-like geometry to two equivalent Sr(1) and two equivalent Ti(1) atoms.