The crystal structure described by Na4CaFe4(PO4)6 crystallizes in the monoclinic C2 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(4), one O(9), two equivalent O(12), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(11), two equivalent O(7), and two equivalent O(8) atoms. In the third Na site, Na(3) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(12), and two equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(9) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent P(4)O4 tetrahedra and  an edgeedge with one P(2)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to one O(2), one O(4), one O(5), and one O(8) atom. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one P(3), one O(10), one O(11), one O(2), and one O(3) atom. There are four inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(7) atom. In the second P site, P(2) is bonded to two equivalent O(11) and two equivalent O(5) atoms to form PO4 tetrahedra that share  an edgeedge with one Ca(1)O6 pentagonal pyramid. In the third P site, P(3) is bonded in a 3-coordinate geometry to one Fe(2), one O(1), one O(6), and one O(7) atom. In the fourth P site, P(4) is bonded to two equivalent O(8) and two equivalent O(9) atoms to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(3), one P(1), and one P(3) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(3), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Na(1) and one Fe(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Ca(1), and one P(3) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(2), one P(1), and one P(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(1), one Ca(1), and one P(4) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Fe(2) and one O(12) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(2), one Fe(2), and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted see-saw-like geometry to one Na(3), two equivalent Na(1), and one O(10) atom. is represented by the CIF file [CIF]
data_Na4CaFe4(PO4)6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.447
_cell_length_b   9.447
_cell_length_c   7.215
_cell_angle_alpha   72.833
_cell_angle_beta   72.833
_cell_angle_gamma   96.161
_symmetry_Int_Tables_number   1
_cell_volume   574.316
_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
  Na  Na0  1  0.481  0.585  0.206  1.0
  Na  Na1  1  0.996  0.004  0.500  1.0
  Na  Na2  1  0.637  0.363  0.500  1.0
  Na  Na3  1  0.415  0.519  0.794  1.0
  Ca  Ca4  1  0.234  0.766  0.000  1.0
  Fe  Fe5  1  0.334  0.090  0.135  1.0
  Fe  Fe6  1  0.910  0.666  0.865  1.0
  Fe  Fe7  1  0.018  0.325  0.707  1.0
  Fe  Fe8  1  0.675  0.982  0.293  1.0
  P  P9  1  0.893  0.340  0.160  1.0
  P  P10  1  0.020  0.980  0.000  1.0
  P  P11  1  0.660  0.107  0.840  1.0
  P  P12  1  0.591  0.931  0.673  1.0
  P  P13  1  0.212  0.788  0.500  1.0
  P  P14  1  0.069  0.409  0.327  1.0
  O  O15  1  0.532  0.090  0.735  1.0
  O  O16  1  0.962  0.425  0.925  1.0
  O  O17  1  0.763  0.261  0.752  1.0
  O  O18  1  0.394  0.285  0.029  1.0
  O  O19  1  0.176  0.996  0.039  1.0
  O  O20  1  0.488  0.792  0.847  1.0
  O  O21  1  0.208  0.512  0.153  1.0
  O  O22  1  0.004  0.824  0.961  1.0
  O  O23  1  0.715  0.606  0.971  1.0
  O  O24  1  0.017  0.260  0.249  1.0
  O  O25  1  0.739  0.237  0.248  1.0
  O  O26  1  0.575  0.038  0.075  1.0
  O  O27  1  0.254  0.968  0.431  1.0
  O  O28  1  0.286  0.744  0.310  1.0
  O  O29  1  0.910  0.468  0.265  1.0
  O  O30  1  0.250  0.356  0.555  1.0
  O  O31  1  0.021  0.105  0.806  1.0
  O  O32  1  0.612  0.610  0.444  1.0
  O  O33  1  0.390  0.388  0.556  1.0
  O  O34  1  0.895  0.979  0.194  1.0
  O  O35  1  0.644  0.750  0.445  1.0
  O  O36  1  0.256  0.714  0.690  1.0
  O  O37  1  0.032  0.746  0.569  1.0
  O  O38  1  0.740  0.983  0.751  1.0
[/CIF]
.
The crystal structure described by Na4CaFe4(PO4)6 crystallizes in the monoclinic C2 space group. There are three inequivalent Na sites. In the first Na site, Na(1) is bonded in a 6-coordinate geometry to one O(4), one O(9), two equivalent O(12), and two equivalent O(6) atoms. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to two equivalent O(11), two equivalent O(7), and two equivalent O(8) atoms. In the third Na site, Na(3) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(12), and two equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(5), two equivalent O(6), and two equivalent O(9) atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent P(4)O4 tetrahedra and  an edgeedge with one P(2)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 4-coordinate geometry to one O(2), one O(4), one O(5), and one O(8) atom. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one P(3), one O(10), one O(11), one O(2), and one O(3) atom. There are four inequivalent P sites. In the first P site, P(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(7) atom. In the second P site, P(2) is bonded to two equivalent O(11) and two equivalent O(5) atoms to form PO4 tetrahedra that share  an edgeedge with one Ca(1)O6 pentagonal pyramid. In the third P site, P(3) is bonded in a 3-coordinate geometry to one Fe(2), one O(1), one O(6), and one O(7) atom. In the fourth P site, P(4) is bonded to two equivalent O(8) and two equivalent O(9) atoms to form PO4 tetrahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Na(3), one P(1), and one P(3) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Fe(1), one Fe(2), and one P(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(3), one Fe(2), and one P(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Na(1) and one Fe(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ca(1), one Fe(1), and one P(2) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Ca(1), and one P(3) atom. In the seventh O site, O(7) is bonded in a 3-coordinate geometry to one Na(2), one P(1), and one P(3) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Na(2), one Fe(1), and one P(4) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Na(1), one Ca(1), and one P(4) atom. In the tenth O site, O(10) is bonded in a 2-coordinate geometry to one Fe(2) and one O(12) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Na(2), one Fe(2), and one P(2) atom. In the twelfth O site, O(12) is bonded in a distorted see-saw-like geometry to one Na(3), two equivalent Na(1), and one O(10) atom. is represented by the CIF file [CIF]
data_Na4CaFe4(PO4)6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.447
_cell_length_b   9.447
_cell_length_c   7.215
_cell_angle_alpha   72.833
_cell_angle_beta   72.833
_cell_angle_gamma   96.161
_symmetry_Int_Tables_number   1
_cell_volume   574.316
_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
  Na  Na0  1  0.481  0.585  0.206  1.0
  Na  Na1  1  0.996  0.004  0.500  1.0
  Na  Na2  1  0.637  0.363  0.500  1.0
  Na  Na3  1  0.415  0.519  0.794  1.0
  Ca  Ca4  1  0.234  0.766  0.000  1.0
  Fe  Fe5  1  0.334  0.090  0.135  1.0
  Fe  Fe6  1  0.910  0.666  0.865  1.0
  Fe  Fe7  1  0.018  0.325  0.707  1.0
  Fe  Fe8  1  0.675  0.982  0.293  1.0
  P  P9  1  0.893  0.340  0.160  1.0
  P  P10  1  0.020  0.980  0.000  1.0
  P  P11  1  0.660  0.107  0.840  1.0
  P  P12  1  0.591  0.931  0.673  1.0
  P  P13  1  0.212  0.788  0.500  1.0
  P  P14  1  0.069  0.409  0.327  1.0
  O  O15  1  0.532  0.090  0.735  1.0
  O  O16  1  0.962  0.425  0.925  1.0
  O  O17  1  0.763  0.261  0.752  1.0
  O  O18  1  0.394  0.285  0.029  1.0
  O  O19  1  0.176  0.996  0.039  1.0
  O  O20  1  0.488  0.792  0.847  1.0
  O  O21  1  0.208  0.512  0.153  1.0
  O  O22  1  0.004  0.824  0.961  1.0
  O  O23  1  0.715  0.606  0.971  1.0
  O  O24  1  0.017  0.260  0.249  1.0
  O  O25  1  0.739  0.237  0.248  1.0
  O  O26  1  0.575  0.038  0.075  1.0
  O  O27  1  0.254  0.968  0.431  1.0
  O  O28  1  0.286  0.744  0.310  1.0
  O  O29  1  0.910  0.468  0.265  1.0
  O  O30  1  0.250  0.356  0.555  1.0
  O  O31  1  0.021  0.105  0.806  1.0
  O  O32  1  0.612  0.610  0.444  1.0
  O  O33  1  0.390  0.388  0.556  1.0
  O  O34  1  0.895  0.979  0.194  1.0
  O  O35  1  0.644  0.750  0.445  1.0
  O  O36  1  0.256  0.714  0.690  1.0
  O  O37  1  0.032  0.746  0.569  1.0
  O  O38  1  0.740  0.983  0.751  1.0
[/CIF]
.