The material structure described by Na3Mg2P5O16 crystallizes in the monoclinic P2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4), one O(7), one O(8), and two equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to two equivalent O(5) and two equivalent O(6) atoms. Mg(1) is bonded to one O(1), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with three equivalent P(3)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(3) and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second P site, P(2) 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,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-46°. In the third P site, P(3) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-48°. There are eight inequivalent O sites. In the first O site, O(8) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(1), and one P(3) atom. In the second O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1), one Mg(1), and one P(2) atom. In the third O site, O(2) is bonded in a bent 120 degrees geometry to one P(2) and one P(3) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), and one P(2) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Mg(1), and one P(3) atom. In the seventh O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Mg(1), and one P(1) atom. In the eighth O site, O(7) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(1), and one P(3) atom. is represented by the CIF file [CIF]
data_Na3Mg2P5O16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.943
_cell_length_b   5.240
_cell_length_c   18.841
_cell_angle_alpha   89.767
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   685.528
_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  0.648  0.748  0.032  1.0
  Na  Na1  1  0.034  0.500  0.750  1.0
  Na  Na2  1  0.352  0.252  0.968  1.0
  Na  Na3  1  0.352  0.748  0.532  1.0
  Na  Na4  1  0.966  0.500  0.250  1.0
  Na  Na5  1  0.648  0.252  0.468  1.0
  Mg  Mg6  1  0.178  0.731  0.092  1.0
  Mg  Mg7  1  0.178  0.269  0.408  1.0
  Mg  Mg8  1  0.822  0.269  0.908  1.0
  Mg  Mg9  1  0.822  0.731  0.592  1.0
  P  P10  1  0.741  0.000  0.750  1.0
  P  P11  1  0.259  0.000  0.250  1.0
  P  P12  1  0.474  0.242  0.130  1.0
  P  P13  1  0.474  0.758  0.370  1.0
  P  P14  1  0.878  0.772  0.417  1.0
  P  P15  1  0.526  0.758  0.870  1.0
  P  P16  1  0.122  0.772  0.917  1.0
  P  P17  1  0.122  0.228  0.583  1.0
  P  P18  1  0.526  0.242  0.630  1.0
  P  P19  1  0.878  0.228  0.083  1.0
  O  O20  1  0.399  0.037  0.081  1.0
  O  O21  1  0.601  0.963  0.919  1.0
  O  O22  1  0.601  0.037  0.581  1.0
  O  O23  1  0.700  0.787  0.356  1.0
  O  O24  1  0.399  0.963  0.419  1.0
  O  O25  1  0.596  0.808  0.790  1.0
  O  O26  1  0.431  0.514  0.109  1.0
  O  O27  1  0.978  0.596  0.881  1.0
  O  O28  1  0.149  0.162  0.301  1.0
  O  O29  1  0.217  0.340  0.516  1.0
  O  O30  1  0.978  0.404  0.619  1.0
  O  O31  1  0.022  0.596  0.381  1.0
  O  O32  1  0.937  0.049  0.426  1.0
  O  O33  1  0.851  0.162  0.801  1.0
  O  O34  1  0.217  0.660  0.984  1.0
  O  O35  1  0.431  0.486  0.391  1.0
  O  O36  1  0.404  0.192  0.210  1.0
  O  O37  1  0.937  0.951  0.074  1.0
  O  O38  1  0.063  0.951  0.574  1.0
  O  O39  1  0.596  0.192  0.710  1.0
  O  O40  1  0.783  0.340  0.016  1.0
  O  O41  1  0.149  0.838  0.199  1.0
  O  O42  1  0.300  0.787  0.856  1.0
  O  O43  1  0.022  0.404  0.119  1.0
  O  O44  1  0.063  0.049  0.926  1.0
  O  O45  1  0.569  0.486  0.891  1.0
  O  O46  1  0.300  0.213  0.644  1.0
  O  O47  1  0.569  0.514  0.609  1.0
  O  O48  1  0.783  0.660  0.484  1.0
  O  O49  1  0.700  0.213  0.144  1.0
  O  O50  1  0.404  0.808  0.290  1.0
  O  O51  1  0.851  0.838  0.699  1.0
[/CIF]
.
The material structure described by Na3Mg2P5O16 crystallizes in the monoclinic P2/c space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 5-coordinate geometry to one O(4), one O(7), one O(8), and two equivalent O(1) atoms. In the second Na site, Na(2) is bonded in a 4-coordinate geometry to two equivalent O(5) and two equivalent O(6) atoms. Mg(1) is bonded to one O(1), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form MgO6 octahedra that share  a cornercorner with one P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and corners with three equivalent P(3)O4 tetrahedra. There are three inequivalent P sites. In the first P site, P(1) is bonded to two equivalent O(3) and two equivalent O(6) atoms to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and corners with two equivalent P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. In the second P site, P(2) 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,  a cornercorner with one P(1)O4 tetrahedra, and  a cornercorner with one P(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 44-46°. In the third P site, P(3) is bonded to one O(2), one O(5), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra and  a cornercorner with one P(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-48°. There are eight inequivalent O sites. In the first O site, O(8) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(1), and one P(3) atom. In the second O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Na(1), one Mg(1), and one P(2) atom. In the third O site, O(2) is bonded in a bent 120 degrees geometry to one P(2) and one P(3) atom. In the fourth O site, O(3) is bonded in a bent 150 degrees geometry to one P(1) and one P(2) atom. In the fifth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Mg(1), and one P(2) atom. In the sixth O site, O(5) is bonded in a 3-coordinate geometry to one Na(2), one Mg(1), and one P(3) atom. In the seventh O site, O(6) is bonded in a 3-coordinate geometry to one Na(2), one Mg(1), and one P(1) atom. In the eighth O site, O(7) is bonded in a distorted trigonal planar geometry to one Na(1), one Mg(1), and one P(3) atom. is represented by the CIF file [CIF]
data_Na3Mg2P5O16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.943
_cell_length_b   5.240
_cell_length_c   18.841
_cell_angle_alpha   89.767
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   685.528
_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  0.648  0.748  0.032  1.0
  Na  Na1  1  0.034  0.500  0.750  1.0
  Na  Na2  1  0.352  0.252  0.968  1.0
  Na  Na3  1  0.352  0.748  0.532  1.0
  Na  Na4  1  0.966  0.500  0.250  1.0
  Na  Na5  1  0.648  0.252  0.468  1.0
  Mg  Mg6  1  0.178  0.731  0.092  1.0
  Mg  Mg7  1  0.178  0.269  0.408  1.0
  Mg  Mg8  1  0.822  0.269  0.908  1.0
  Mg  Mg9  1  0.822  0.731  0.592  1.0
  P  P10  1  0.741  0.000  0.750  1.0
  P  P11  1  0.259  0.000  0.250  1.0
  P  P12  1  0.474  0.242  0.130  1.0
  P  P13  1  0.474  0.758  0.370  1.0
  P  P14  1  0.878  0.772  0.417  1.0
  P  P15  1  0.526  0.758  0.870  1.0
  P  P16  1  0.122  0.772  0.917  1.0
  P  P17  1  0.122  0.228  0.583  1.0
  P  P18  1  0.526  0.242  0.630  1.0
  P  P19  1  0.878  0.228  0.083  1.0
  O  O20  1  0.399  0.037  0.081  1.0
  O  O21  1  0.601  0.963  0.919  1.0
  O  O22  1  0.601  0.037  0.581  1.0
  O  O23  1  0.700  0.787  0.356  1.0
  O  O24  1  0.399  0.963  0.419  1.0
  O  O25  1  0.596  0.808  0.790  1.0
  O  O26  1  0.431  0.514  0.109  1.0
  O  O27  1  0.978  0.596  0.881  1.0
  O  O28  1  0.149  0.162  0.301  1.0
  O  O29  1  0.217  0.340  0.516  1.0
  O  O30  1  0.978  0.404  0.619  1.0
  O  O31  1  0.022  0.596  0.381  1.0
  O  O32  1  0.937  0.049  0.426  1.0
  O  O33  1  0.851  0.162  0.801  1.0
  O  O34  1  0.217  0.660  0.984  1.0
  O  O35  1  0.431  0.486  0.391  1.0
  O  O36  1  0.404  0.192  0.210  1.0
  O  O37  1  0.937  0.951  0.074  1.0
  O  O38  1  0.063  0.951  0.574  1.0
  O  O39  1  0.596  0.192  0.710  1.0
  O  O40  1  0.783  0.340  0.016  1.0
  O  O41  1  0.149  0.838  0.199  1.0
  O  O42  1  0.300  0.787  0.856  1.0
  O  O43  1  0.022  0.404  0.119  1.0
  O  O44  1  0.063  0.049  0.926  1.0
  O  O45  1  0.569  0.486  0.891  1.0
  O  O46  1  0.300  0.213  0.644  1.0
  O  O47  1  0.569  0.514  0.609  1.0
  O  O48  1  0.783  0.660  0.484  1.0
  O  O49  1  0.700  0.213  0.144  1.0
  O  O50  1  0.404  0.808  0.290  1.0
  O  O51  1  0.851  0.838  0.699  1.0
[/CIF]
.