data_NaYSe
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.81
_cell_length_b   4.81
_cell_length_c   4.81
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaYSe
_chemical_formula_sum   'Na1 Y1 Se1'
_cell_volume   78.46
_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  0.0  0.0  0.0  1.0
  Y  Y2  1  0.4  0.4  0.4  1.0
  Se  Se1  1  0.7  0.7  0.7  1.0

data_NaYSe
_symmetry_space_group_name_H-M   R3m
_cell_length_a   4.81
_cell_length_b   4.81
_cell_length_c   11.77
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   NaYSe
_chemical_formula_sum   'Na3 Y3 Se3'
_cell_volume   235.38
_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
  Na  Na0  3  0.0  0.0  0.0  1.0
  Y  Y1  3  0.0  0.0  0.6  1.0
  Se  Se2  3  0.0  0.0  0.3  1.0

Na Y Se
NaYSe is half-Heusler structured and crystallizes in the trigonal R3m space group. Na(1) is bonded in a 7-coordinate geometry to three equivalent Y(1) and four equivalent Se(1) atoms. All Na(1)-Y(1) bond lengths are 2.88 Å. There are three shorter (2.80 Å) and one longer (3.54 Å) Na(1)-Se(1) bond length. Y(1) is bonded to three equivalent Na(1) and four equivalent Se(1) atoms to form distorted YNa3Se4 hexagonal pyramids that share corners with six equivalent Se(1)Na4Y4 hexagonal bipyramids, corners with six equivalent Y(1)Na3Se4 hexagonal pyramids, edges with three equivalent Se(1)Na4Y4 hexagonal bipyramids, and edges with six equivalent Y(1)Na3Se4 hexagonal pyramids. There are three shorter (2.80 Å) and one longer (3.54 Å) Y(1)-Se(1) bond length. Se(1) is bonded to four equivalent Na(1) and four equivalent Y(1) atoms to form distorted SeNa4Y4 hexagonal bipyramids that share corners with six equivalent Y(1)Na3Se4 hexagonal pyramids, edges with twelve equivalent Se(1)Na4Y4 hexagonal bipyramids, and edges with three equivalent Y(1)Na3Se4 hexagonal pyramids.