data_Ca2MgTa
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.67
_cell_length_b   6.67
_cell_length_c   6.67
_cell_angle_alpha   151.19
_cell_angle_beta   129.81
_cell_angle_gamma   58.91
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2MgTa
_chemical_formula_sum   'Ca2 Mg1 Ta1'
_cell_volume   108.91
_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
  Ca  Ca0  1  0.0  0.0  0.38  1.0
  Ca  Ca1  1  0.66  0.0  0.13  1.0
  Mg  Mg2  1  0.0  0.0  0.07  1.0
  Ta  Ta3  1  0.0  0.83  0.65  1.0

data_Ca2MgTa
_symmetry_space_group_name_H-M   P1
_cell_length_a   3.32
_cell_length_b   5.66
_cell_length_c   6.67
_cell_angle_alpha   115.1
_cell_angle_beta   104.4
_cell_angle_gamma   90.0
_symmetry_Int_Tables_number   1
_chemical_formula_structural   Ca2MgTa
_chemical_formula_sum   'Ca2 Mg1 Ta1'
_cell_volume   108.91
_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
  Ca  Ca0  1  0.0  0.13  0.47  1.0
  Ca  Ca1  1  0.0  0.38  0.38  1.0
  Mg  Mg2  1  0.0  0.07  0.07  1.0
  Ta  Ta3  1  0.17  0.82  0.82  1.0

Ca Ca Mg Ta
Ca2MgTa crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a distorted T-shaped geometry to one Ca(2), one Mg(1), and one Ta(1) atom. The Ca(1)-Ca(2) bond length is 1.77 Å. The Ca(1)-Mg(1) bond length is 2.12 Å. The Ca(1)-Ta(1) bond length is 2.80 Å. In the second Ca site, Ca(2) is bonded in a 3-coordinate geometry to one Ca(1), one Mg(1), and one Ta(1) atom. The Ca(2)-Mg(1) bond length is 2.55 Å. The Ca(2)-Ta(1) bond length is 3.41 Å. Mg(1) is bonded in a 2-coordinate geometry to one Ca(1), one Ca(2), and two equivalent Ta(1) atoms. There is one shorter (1.89 Å) and one longer (2.83 Å) Mg(1)-Ta(1) bond length. Ta(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), and two equivalent Mg(1) atoms.