The crystal structure described by Na2Ca(CO3)2 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 9-coordinate geometry to three equivalent O(1) and six equivalent O(2) atoms. In the second Na site, Na(2) is bonded in an octahedral geometry to three equivalent O(1) and three equivalent O(2) atoms. Ca(1) is bonded in a 11-coordinate geometry to two equivalent C(2), three equivalent O(2), and six equivalent O(1) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to three equivalent O(1) atoms. In the second C site, C(2) is bonded in a trigonal planar geometry to two equivalent Ca(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), two equivalent Ca(1), and one C(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Na(2), two equivalent Na(1), one Ca(1), and one C(2) atom. is represented by the CIF card [CIF]
data_Na2Ca(CO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.222
_cell_length_b   5.222
_cell_length_c   11.538
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   272.471
_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
  Na  Na0  1  0.667  0.333  0.693  1.0
  Na  Na1  1  0.333  0.667  0.193  1.0
  Na  Na2  1  0.667  0.333  0.362  1.0
  Na  Na3  1  0.333  0.667  0.862  1.0
  Ca  Ca4  1  0.000  0.000  0.021  1.0
  Ca  Ca5  1  0.000  0.000  0.521  1.0
  C  C6  1  0.667  0.333  0.003  1.0
  C  C7  1  0.333  0.667  0.503  1.0
  C  C8  1  0.000  0.000  0.745  1.0
  C  C9  1  0.000  0.000  0.245  1.0
  O  O10  1  0.523  0.045  0.002  1.0
  O  O11  1  0.523  0.477  0.002  1.0
  O  O12  1  0.477  0.955  0.502  1.0
  O  O13  1  0.955  0.477  0.002  1.0
  O  O14  1  0.477  0.523  0.502  1.0
  O  O15  1  0.045  0.523  0.502  1.0
  O  O16  1  0.143  0.287  0.740  1.0
  O  O17  1  0.143  0.857  0.740  1.0
  O  O18  1  0.857  0.713  0.240  1.0
  O  O19  1  0.713  0.857  0.740  1.0
  O  O20  1  0.857  0.143  0.240  1.0
  O  O21  1  0.287  0.143  0.240  1.0
[/CIF]
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The crystal structure described by Na2Ca(CO3)2 crystallizes in the hexagonal P6_3mc space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 9-coordinate geometry to three equivalent O(1) and six equivalent O(2) atoms. In the second Na site, Na(2) is bonded in an octahedral geometry to three equivalent O(1) and three equivalent O(2) atoms. Ca(1) is bonded in a 11-coordinate geometry to two equivalent C(2), three equivalent O(2), and six equivalent O(1) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded in a trigonal planar geometry to three equivalent O(1) atoms. In the second C site, C(2) is bonded in a trigonal planar geometry to two equivalent Ca(1) and three equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), one Na(2), two equivalent Ca(1), and one C(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Na(2), two equivalent Na(1), one Ca(1), and one C(2) atom. is represented by the CIF card [CIF]
data_Na2Ca(CO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.222
_cell_length_b   5.222
_cell_length_c   11.538
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   272.471
_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
  Na  Na0  1  0.667  0.333  0.693  1.0
  Na  Na1  1  0.333  0.667  0.193  1.0
  Na  Na2  1  0.667  0.333  0.362  1.0
  Na  Na3  1  0.333  0.667  0.862  1.0
  Ca  Ca4  1  0.000  0.000  0.021  1.0
  Ca  Ca5  1  0.000  0.000  0.521  1.0
  C  C6  1  0.667  0.333  0.003  1.0
  C  C7  1  0.333  0.667  0.503  1.0
  C  C8  1  0.000  0.000  0.745  1.0
  C  C9  1  0.000  0.000  0.245  1.0
  O  O10  1  0.523  0.045  0.002  1.0
  O  O11  1  0.523  0.477  0.002  1.0
  O  O12  1  0.477  0.955  0.502  1.0
  O  O13  1  0.955  0.477  0.002  1.0
  O  O14  1  0.477  0.523  0.502  1.0
  O  O15  1  0.045  0.523  0.502  1.0
  O  O16  1  0.143  0.287  0.740  1.0
  O  O17  1  0.143  0.857  0.740  1.0
  O  O18  1  0.857  0.713  0.240  1.0
  O  O19  1  0.713  0.857  0.740  1.0
  O  O20  1  0.857  0.143  0.240  1.0
  O  O21  1  0.287  0.143  0.240  1.0
[/CIF]
.