data_NaSrBeTl
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   5.21
_cell_angle_alpha   60.0
_cell_angle_beta   60.0
_cell_angle_gamma   60.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   NaSrBeTl
_chemical_formula_sum   'Na1 Sr1 Be1 Tl1'
_cell_volume   99.89
_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  0.52  0.52  0.52  1.0
  Sr  Sr2  1  0.68  0.68  0.68  1.0
  Be  Be0  1  0.0  0.0  0.0  1.0
  Tl  Tl3  1  0.84  0.84  0.84  1.0

data_NaSrBeTl
_symmetry_space_group_name_H-M   R3m
_cell_length_a   5.21
_cell_length_b   5.21
_cell_length_c   12.76
_cell_angle_alpha   90.0
_cell_angle_beta   90.0
_cell_angle_gamma   120.0
_symmetry_Int_Tables_number   160
_chemical_formula_structural   NaSrBeTl
_chemical_formula_sum   'Na3 Sr3 Be3 Tl3'
_cell_volume   299.67
_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  0.48  1.0
  Sr  Sr1  3  0.0  0.0  0.32  1.0
  Be  Be2  3  0.0  0.0  -0.0  1.0
  Tl  Tl3  3  0.0  0.0  0.16  1.0

Na Sr Be Tl
NaSrBeTl crystallizes in the trigonal R3m space group. Na(1) is bonded to one Sr(1) and three equivalent Tl(1) atoms to form NaSrTl3 trigonal pyramids that share  a cornercorner with one Tl(1)Na3SrBe trigonal bipyramid, corners with six equivalent Na(1)SrTl3 trigonal pyramids, and edges with three equivalent Be(1)Sr3Tl trigonal pyramids. The Na(1)-Sr(1) bond length is 2.02 Å. All Na(1)-Tl(1) bond lengths are 3.01 Å. Sr(1) is bonded in a distorted single-bond geometry to one Na(1), three equivalent Be(1), and one Tl(1) atom. All Sr(1)-Be(1) bond lengths are 3.01 Å. The Sr(1)-Tl(1) bond length is 2.02 Å. Be(1) is bonded to three equivalent Sr(1) and one Tl(1) atom to form BeSr3Tl trigonal pyramids that share corners with three equivalent Tl(1)Na3SrBe trigonal bipyramids, corners with six equivalent Be(1)Sr3Tl trigonal pyramids, and edges with three equivalent Na(1)SrTl3 trigonal pyramids. The Be(1)-Tl(1) bond length is 2.02 Å. Tl(1) is bonded to three equivalent Na(1), one Sr(1), and one Be(1) atom to form distorted TlNa3SrBe trigonal bipyramids that share corners with six equivalent Tl(1)Na3SrBe trigonal bipyramids,  a cornercorner with one Na(1)SrTl3 trigonal pyramid, and corners with three equivalent Be(1)Sr3Tl trigonal pyramids.