The crystal structure described by Na2Ca(PO4)2 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(5), one O(6), one O(7), and one O(8) atom. In the second Na site, Na(2) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NaO5 trigonal bipyramids that share corners with two equivalent Ca(1)O7 pentagonal bipyramids,  a cornercorner with one P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. Ca(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids,  an edgeedge with one P(2)O4 tetrahedra, and  an edgeedge with one Na(2)O5 trigonal bipyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Ca(1)O7 pentagonal bipyramids and corners with four equivalent Na(2)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O7 pentagonal bipyramids,  a cornercorner with one Na(2)O5 trigonal bipyramid, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted tetrahedral geometry to one Na(1), one Na(2), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Ca(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ca(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ca(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Ca(1), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Na(1), one Ca(1), and one P(2) atom. is represented by the CIF file [CIF]
data_Na2Ca(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.247
_cell_length_b   5.505
_cell_length_c   9.164
_cell_angle_alpha   80.959
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   361.062
_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  0.984  0.937  0.242  1.0
  Na  Na1  1  0.484  0.063  0.758  1.0
  Na  Na2  1  0.228  0.325  0.384  1.0
  Na  Na3  1  0.728  0.675  0.616  1.0
  Ca  Ca4  1  0.504  0.803  0.233  1.0
  Ca  Ca5  1  0.004  0.197  0.767  1.0
  P  P6  1  0.721  0.238  0.424  1.0
  P  P7  1  0.221  0.762  0.576  1.0
  P  P8  1  0.358  0.306  0.037  1.0
  P  P9  1  0.858  0.694  0.963  1.0
  O  O10  1  0.365  0.572  0.070  1.0
  O  O11  1  0.865  0.428  0.930  1.0
  O  O12  1  0.694  0.968  0.400  1.0
  O  O13  1  0.194  0.032  0.600  1.0
  O  O14  1  0.901  0.340  0.342  1.0
  O  O15  1  0.401  0.660  0.658  1.0
  O  O16  1  0.555  0.401  0.369  1.0
  O  O17  1  0.055  0.599  0.631  1.0
  O  O18  1  0.749  0.245  0.592  1.0
  O  O19  1  0.249  0.755  0.408  1.0
  O  O20  1  0.247  0.139  0.157  1.0
  O  O21  1  0.747  0.861  0.843  1.0
  O  O22  1  0.282  0.295  0.881  1.0
  O  O23  1  0.782  0.705  0.119  1.0
  O  O24  1  0.055  0.810  0.950  1.0
  O  O25  1  0.555  0.190  0.050  1.0
[/CIF]
.
The crystal structure described by Na2Ca(PO4)2 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(5), one O(6), one O(7), and one O(8) atom. In the second Na site, Na(2) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form NaO5 trigonal bipyramids that share corners with two equivalent Ca(1)O7 pentagonal bipyramids,  a cornercorner with one P(2)O4 tetrahedra, corners with four equivalent P(1)O4 tetrahedra, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. Ca(1) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted CaO7 pentagonal bipyramids that share corners with two equivalent P(2)O4 tetrahedra, corners with three equivalent P(1)O4 tetrahedra, corners with two equivalent Na(2)O5 trigonal bipyramids,  an edgeedge with one P(2)O4 tetrahedra, and  an edgeedge with one Na(2)O5 trigonal bipyramid. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form PO4 tetrahedra that share corners with three equivalent Ca(1)O7 pentagonal bipyramids and corners with four equivalent Na(2)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(1), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Ca(1)O7 pentagonal bipyramids,  a cornercorner with one Na(2)O5 trigonal bipyramid, and  an edgeedge with one Ca(1)O7 pentagonal bipyramid. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Ca(1) and one P(2) atom. In the second O site, O(2) is bonded in a distorted tetrahedral geometry to one Na(1), one Na(2), one Ca(1), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(2), one Ca(1), and one P(1) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ca(1), and one P(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Ca(1), and one P(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Na(1), one Ca(1), and one P(2) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Na(1), one Ca(1), and one P(2) atom. is represented by the CIF file [CIF]
data_Na2Ca(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.247
_cell_length_b   5.505
_cell_length_c   9.164
_cell_angle_alpha   80.959
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   361.062
_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  0.984  0.937  0.242  1.0
  Na  Na1  1  0.484  0.063  0.758  1.0
  Na  Na2  1  0.228  0.325  0.384  1.0
  Na  Na3  1  0.728  0.675  0.616  1.0
  Ca  Ca4  1  0.504  0.803  0.233  1.0
  Ca  Ca5  1  0.004  0.197  0.767  1.0
  P  P6  1  0.721  0.238  0.424  1.0
  P  P7  1  0.221  0.762  0.576  1.0
  P  P8  1  0.358  0.306  0.037  1.0
  P  P9  1  0.858  0.694  0.963  1.0
  O  O10  1  0.365  0.572  0.070  1.0
  O  O11  1  0.865  0.428  0.930  1.0
  O  O12  1  0.694  0.968  0.400  1.0
  O  O13  1  0.194  0.032  0.600  1.0
  O  O14  1  0.901  0.340  0.342  1.0
  O  O15  1  0.401  0.660  0.658  1.0
  O  O16  1  0.555  0.401  0.369  1.0
  O  O17  1  0.055  0.599  0.631  1.0
  O  O18  1  0.749  0.245  0.592  1.0
  O  O19  1  0.249  0.755  0.408  1.0
  O  O20  1  0.247  0.139  0.157  1.0
  O  O21  1  0.747  0.861  0.843  1.0
  O  O22  1  0.282  0.295  0.881  1.0
  O  O23  1  0.782  0.705  0.119  1.0
  O  O24  1  0.055  0.810  0.950  1.0
  O  O25  1  0.555  0.190  0.050  1.0
[/CIF]
.