The compound described by Na4MgFe(PO4)3 crystallizes in the trigonal R3c 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(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(3) and three equivalent O(4) atoms. Mg(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. Fe(1) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-40°. There are four inequivalent O sites. In the first O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one P(1) atom to form distorted ONa3MgP trigonal bipyramids that share corners with six equivalent O(4)Na3FeP trigonal bipyramids,  an edgeedge with one O(4)Na3FeP trigonal bipyramid, and faces with two equivalent O(3)Na3MgP trigonal bipyramids. In the second O site, O(4) is bonded to one Na(2), two equivalent Na(1), one Fe(1), and one P(1) atom to form distorted ONa3FeP trigonal bipyramids that share corners with six equivalent O(3)Na3MgP trigonal bipyramids,  an edgeedge with one O(3)Na3MgP trigonal bipyramid, and faces with two equivalent O(4)Na3FeP trigonal bipyramids. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one Na(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na4MgFe(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.892
_cell_length_b   8.892
_cell_length_c   8.892
_cell_angle_alpha   60.566
_cell_angle_beta   60.566
_cell_angle_gamma   60.566
_symmetry_Int_Tables_number   1
_cell_volume   503.495
_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  0.744  0.116  0.386  1.0
  Na  Na1  1  0.386  0.744  0.116  1.0
  Na  Na2  1  0.116  0.386  0.744  1.0
  Na  Na3  1  0.886  0.616  0.244  1.0
  Na  Na4  1  0.244  0.886  0.616  1.0
  Na  Na5  1  0.616  0.244  0.886  1.0
  Na  Na6  1  0.498  0.498  0.498  1.0
  Na  Na7  1  0.998  0.998  0.998  1.0
  Mg  Mg8  1  0.351  0.351  0.351  1.0
  Mg  Mg9  1  0.851  0.851  0.851  1.0
  Fe  Fe10  1  0.650  0.650  0.650  1.0
  Fe  Fe11  1  0.150  0.150  0.150  1.0
  P  P12  1  0.753  0.453  0.047  1.0
  P  P13  1  0.047  0.753  0.453  1.0
  P  P14  1  0.453  0.047  0.753  1.0
  P  P15  1  0.547  0.953  0.253  1.0
  P  P16  1  0.253  0.547  0.953  1.0
  P  P17  1  0.953  0.253  0.547  1.0
  O  O18  1  0.118  0.291  0.517  1.0
  O  O19  1  0.517  0.118  0.291  1.0
  O  O20  1  0.291  0.517  0.118  1.0
  O  O21  1  0.017  0.791  0.618  1.0
  O  O22  1  0.618  0.017  0.791  1.0
  O  O23  1  0.791  0.618  0.017  1.0
  O  O24  1  0.876  0.718  0.483  1.0
  O  O25  1  0.483  0.876  0.718  1.0
  O  O26  1  0.718  0.483  0.876  1.0
  O  O27  1  0.983  0.218  0.376  1.0
  O  O28  1  0.376  0.983  0.218  1.0
  O  O29  1  0.218  0.376  0.983  1.0
  O  O30  1  0.224  0.589  0.427  1.0
  O  O31  1  0.427  0.224  0.589  1.0
  O  O32  1  0.589  0.427  0.224  1.0
  O  O33  1  0.927  0.089  0.724  1.0
  O  O34  1  0.724  0.927  0.089  1.0
  O  O35  1  0.089  0.724  0.927  1.0
  O  O36  1  0.772  0.421  0.564  1.0
  O  O37  1  0.564  0.772  0.421  1.0
  O  O38  1  0.421  0.564  0.772  1.0
  O  O39  1  0.064  0.921  0.272  1.0
  O  O40  1  0.272  0.064  0.921  1.0
  O  O41  1  0.921  0.272  0.064  1.0
[/CIF]
.
The compound described by Na4MgFe(PO4)3 crystallizes in the trigonal R3c 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(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Na site, Na(2) is bonded in a distorted hexagonal planar geometry to three equivalent O(3) and three equivalent O(4) atoms. Mg(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form MgO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. Fe(1) is bonded to three equivalent O(2) and three equivalent O(4) atoms to form FeO6 octahedra that share corners with six equivalent P(1)O4 tetrahedra. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 29-40°. There are four inequivalent O sites. In the first O site, O(3) is bonded to one Na(2), two equivalent Na(1), one Mg(1), and one P(1) atom to form distorted ONa3MgP trigonal bipyramids that share corners with six equivalent O(4)Na3FeP trigonal bipyramids,  an edgeedge with one O(4)Na3FeP trigonal bipyramid, and faces with two equivalent O(3)Na3MgP trigonal bipyramids. In the second O site, O(4) is bonded to one Na(2), two equivalent Na(1), one Fe(1), and one P(1) atom to form distorted ONa3FeP trigonal bipyramids that share corners with six equivalent O(3)Na3MgP trigonal bipyramids,  an edgeedge with one O(3)Na3MgP trigonal bipyramid, and faces with two equivalent O(4)Na3FeP trigonal bipyramids. In the third O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), and one P(1) atom. In the fourth O site, O(2) is bonded in a 2-coordinate geometry to one Na(1), one Fe(1), and one P(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na4MgFe(PO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.892
_cell_length_b   8.892
_cell_length_c   8.892
_cell_angle_alpha   60.566
_cell_angle_beta   60.566
_cell_angle_gamma   60.566
_symmetry_Int_Tables_number   1
_cell_volume   503.495
_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  0.744  0.116  0.386  1.0
  Na  Na1  1  0.386  0.744  0.116  1.0
  Na  Na2  1  0.116  0.386  0.744  1.0
  Na  Na3  1  0.886  0.616  0.244  1.0
  Na  Na4  1  0.244  0.886  0.616  1.0
  Na  Na5  1  0.616  0.244  0.886  1.0
  Na  Na6  1  0.498  0.498  0.498  1.0
  Na  Na7  1  0.998  0.998  0.998  1.0
  Mg  Mg8  1  0.351  0.351  0.351  1.0
  Mg  Mg9  1  0.851  0.851  0.851  1.0
  Fe  Fe10  1  0.650  0.650  0.650  1.0
  Fe  Fe11  1  0.150  0.150  0.150  1.0
  P  P12  1  0.753  0.453  0.047  1.0
  P  P13  1  0.047  0.753  0.453  1.0
  P  P14  1  0.453  0.047  0.753  1.0
  P  P15  1  0.547  0.953  0.253  1.0
  P  P16  1  0.253  0.547  0.953  1.0
  P  P17  1  0.953  0.253  0.547  1.0
  O  O18  1  0.118  0.291  0.517  1.0
  O  O19  1  0.517  0.118  0.291  1.0
  O  O20  1  0.291  0.517  0.118  1.0
  O  O21  1  0.017  0.791  0.618  1.0
  O  O22  1  0.618  0.017  0.791  1.0
  O  O23  1  0.791  0.618  0.017  1.0
  O  O24  1  0.876  0.718  0.483  1.0
  O  O25  1  0.483  0.876  0.718  1.0
  O  O26  1  0.718  0.483  0.876  1.0
  O  O27  1  0.983  0.218  0.376  1.0
  O  O28  1  0.376  0.983  0.218  1.0
  O  O29  1  0.218  0.376  0.983  1.0
  O  O30  1  0.224  0.589  0.427  1.0
  O  O31  1  0.427  0.224  0.589  1.0
  O  O32  1  0.589  0.427  0.224  1.0
  O  O33  1  0.927  0.089  0.724  1.0
  O  O34  1  0.724  0.927  0.089  1.0
  O  O35  1  0.089  0.724  0.927  1.0
  O  O36  1  0.772  0.421  0.564  1.0
  O  O37  1  0.564  0.772  0.421  1.0
  O  O38  1  0.421  0.564  0.772  1.0
  O  O39  1  0.064  0.921  0.272  1.0
  O  O40  1  0.272  0.064  0.921  1.0
  O  O41  1  0.921  0.272  0.064  1.0
[/CIF]
.