The material described by Mg2Ca crystallizes in the hexagonal P-62m space group. Ca(1) is bonded to three equivalent Ca(1), three equivalent Mg(2), and six equivalent Mg(1) atoms to form CaCa3Mg9 cuboctahedra that share corners with nine equivalent Ca(1)Ca3Mg9 cuboctahedra, corners with nine equivalent Mg(2)Ca6Mg6 cuboctahedra, edges with six equivalent Ca(1)Ca3Mg9 cuboctahedra, faces with three equivalent Mg(2)Ca6Mg6 cuboctahedra, and faces with five equivalent Ca(1)Ca3Mg9 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to four equivalent Ca(1), two equivalent Mg(1), and two equivalent Mg(2) atoms. In the second Mg site, Mg(2) is bonded to six equivalent Ca(1) and six equivalent Mg(1) atoms to form MgCa6Mg6 cuboctahedra that share corners with eighteen equivalent Ca(1)Ca3Mg9 cuboctahedra, edges with six equivalent Mg(2)Ca6Mg6 cuboctahedra, faces with two equivalent Mg(2)Ca6Mg6 cuboctahedra, and faces with six equivalent Ca(1)Ca3Mg9 cuboctahedra. is represented by the CIF card [CIF]
data_CaMg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.005
_cell_length_b   6.005
_cell_length_c   5.535
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   172.820
_cell_formula_units_Z   2
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  0.333  0.667  0.500  1.0
  Ca  Ca1  1  0.667  0.333  0.500  1.0
  Mg  Mg2  1  0.692  0.000  0.000  1.0
  Mg  Mg3  1  0.000  0.692  0.000  1.0
  Mg  Mg4  1  0.308  0.308  0.000  1.0
  Mg  Mg5  1  0.000  0.000  0.500  1.0
[/CIF]
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The material described by Mg2Ca crystallizes in the hexagonal P-62m space group. Ca(1) is bonded to three equivalent Ca(1), three equivalent Mg(2), and six equivalent Mg(1) atoms to form CaCa3Mg9 cuboctahedra that share corners with nine equivalent Ca(1)Ca3Mg9 cuboctahedra, corners with nine equivalent Mg(2)Ca6Mg6 cuboctahedra, edges with six equivalent Ca(1)Ca3Mg9 cuboctahedra, faces with three equivalent Mg(2)Ca6Mg6 cuboctahedra, and faces with five equivalent Ca(1)Ca3Mg9 cuboctahedra. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 8-coordinate geometry to four equivalent Ca(1), two equivalent Mg(1), and two equivalent Mg(2) atoms. In the second Mg site, Mg(2) is bonded to six equivalent Ca(1) and six equivalent Mg(1) atoms to form MgCa6Mg6 cuboctahedra that share corners with eighteen equivalent Ca(1)Ca3Mg9 cuboctahedra, edges with six equivalent Mg(2)Ca6Mg6 cuboctahedra, faces with two equivalent Mg(2)Ca6Mg6 cuboctahedra, and faces with six equivalent Ca(1)Ca3Mg9 cuboctahedra. is represented by the CIF card [CIF]
data_CaMg2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.005
_cell_length_b   6.005
_cell_length_c   5.535
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   172.820
_cell_formula_units_Z   2
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  0.333  0.667  0.500  1.0
  Ca  Ca1  1  0.667  0.333  0.500  1.0
  Mg  Mg2  1  0.692  0.000  0.000  1.0
  Mg  Mg3  1  0.000  0.692  0.000  1.0
  Mg  Mg4  1  0.308  0.308  0.000  1.0
  Mg  Mg5  1  0.000  0.000  0.500  1.0
[/CIF]
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