The material structure described by MgCa3 crystallizes in the hexagonal P-6m2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent Ca(1) and six equivalent Ca(2) atoms to form CaCa12 cuboctahedra that share corners with six equivalent Ca(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with six equivalent Ca(1)Ca12 cuboctahedra, edges with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, and faces with six equivalent Ca(1)Ca12 cuboctahedra. In the second Ca site, Ca(2) is bonded to three equivalent Ca(1) and three equivalent Mg(1) atoms to form distorted CaCa3Mg3 cuboctahedra that share corners with six equivalent Ca(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with six equivalent Ca(1)Ca12 cuboctahedra, edges with six equivalent Ca(2)Ca3Mg3 cuboctahedra, and faces with two equivalent Ca(2)Ca3Mg3 cuboctahedra. Mg(1) is bonded in a 6-coordinate geometry to six equivalent Ca(2) atoms. is represented by the CIF file [CIF]
data_Ca3Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.816
_cell_length_b   3.816
_cell_length_c   11.980
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   151.054
_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  0.667  0.333  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.270  1.0
  Ca  Ca2  1  0.000  0.000  0.730  1.0
  Mg  Mg3  1  0.667  0.333  0.500  1.0
[/CIF]
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The material structure described by MgCa3 crystallizes in the hexagonal P-6m2 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to six equivalent Ca(1) and six equivalent Ca(2) atoms to form CaCa12 cuboctahedra that share corners with six equivalent Ca(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with six equivalent Ca(1)Ca12 cuboctahedra, edges with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, and faces with six equivalent Ca(1)Ca12 cuboctahedra. In the second Ca site, Ca(2) is bonded to three equivalent Ca(1) and three equivalent Mg(1) atoms to form distorted CaCa3Mg3 cuboctahedra that share corners with six equivalent Ca(1)Ca12 cuboctahedra, corners with twelve equivalent Ca(2)Ca3Mg3 cuboctahedra, edges with six equivalent Ca(1)Ca12 cuboctahedra, edges with six equivalent Ca(2)Ca3Mg3 cuboctahedra, and faces with two equivalent Ca(2)Ca3Mg3 cuboctahedra. Mg(1) is bonded in a 6-coordinate geometry to six equivalent Ca(2) atoms. is represented by the CIF file [CIF]
data_Ca3Mg
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.816
_cell_length_b   3.816
_cell_length_c   11.980
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   151.054
_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  0.667  0.333  0.000  1.0
  Ca  Ca1  1  0.000  0.000  0.270  1.0
  Ca  Ca2  1  0.000  0.000  0.730  1.0
  Mg  Mg3  1  0.667  0.333  0.500  1.0
[/CIF]
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