data_Na2CaNb
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.91
_cell_length_b   6.91
_cell_length_c   2.96
_cell_angle_alpha   101.03
_cell_angle_beta   101.03
_cell_angle_gamma   123.5
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2CaNb
_chemical_formula_sum   'Na2 Ca1 Nb1'
_cell_volume   107.63
_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
  Na  Na1  1  0.04  0.04  0.35  1.0
  Na  Na2  1  0.04  0.96  0.35  1.0
  Ca  Ca0  1  0.0  0.0  0.0  1.0
  Nb  Nb3  1  0.27  0.0  0.0  1.0

data_Na2CaNb
_symmetry_space_group_name_H-M   P1
_cell_length_a   2.96
_cell_length_b   5.99
_cell_length_c   6.91
_cell_angle_alpha   114.98
_cell_angle_beta   101.03
_cell_angle_gamma   93.02
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Na2CaNb
_chemical_formula_sum   'Na2 Ca1 Nb1'
_cell_volume   107.63
_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
  Na  Na0  1  0.31  0.96  1.0  1.0
  Na  Na1  1  0.39  0.04  0.08  1.0
  Ca  Ca2  1  0.0  0.0  0.0  1.0
  Nb  Nb3  1  -0.0  0.0  0.27  1.0

Na Na Ca Nb