The material described by Ba2Mg(PO4)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(5), one O(7), one O(8), and two equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(5), one O(6), one O(7), one O(8), and two equivalent O(3) atoms. Mg(1) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-60°. 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. The corner-sharing octahedral tilt angles range from 35-42°. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Ba(1), one Mg(1), and one P(2) atom. In the second O site, O(5) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one P(1) atom. In the third O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ba(2), one Mg(1), and one P(1) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Mg(1), and one P(1) atom. In the fifth O site, O(8) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one P(1) atom. In the sixth O site, O(1) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one P(2) atom. In the seventh O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one P(2) atom. In the eighth O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Ba(2) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2Mg(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.864
_cell_length_b   5.321
_cell_length_c   17.013
_cell_angle_alpha   72.436
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   764.970
_cell_formula_units_Z   4
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
  Ba  Ba0  1  0.657  0.525  0.229  1.0
  Ba  Ba1  1  0.157  0.475  0.271  1.0
  Ba  Ba2  1  0.343  0.475  0.771  1.0
  Ba  Ba3  1  0.843  0.525  0.729  1.0
  Ba  Ba4  1  0.204  0.681  0.520  1.0
  Ba  Ba5  1  0.704  0.319  0.980  1.0
  Ba  Ba6  1  0.796  0.319  0.480  1.0
  Ba  Ba7  1  0.296  0.681  0.020  1.0
  Mg  Mg8  1  0.985  0.907  0.866  1.0
  Mg  Mg9  1  0.485  0.093  0.634  1.0
  Mg  Mg10  1  0.515  0.907  0.366  1.0
  Mg  Mg11  1  0.015  0.093  0.134  1.0
  P  P12  1  0.413  0.313  0.422  1.0
  P  P13  1  0.890  0.919  0.333  1.0
  P  P14  1  0.087  0.313  0.922  1.0
  P  P15  1  0.587  0.687  0.578  1.0
  P  P16  1  0.610  0.919  0.833  1.0
  P  P17  1  0.110  0.081  0.667  1.0
  P  P18  1  0.390  0.081  0.167  1.0
  P  P19  1  0.913  0.687  0.078  1.0
  O  O20  1  0.890  0.208  0.334  1.0
  O  O21  1  0.390  0.792  0.166  1.0
  O  O22  1  0.110  0.792  0.666  1.0
  O  O23  1  0.610  0.208  0.834  1.0
  O  O24  1  0.727  0.816  0.333  1.0
  O  O25  1  0.227  0.184  0.167  1.0
  O  O26  1  0.273  0.184  0.667  1.0
  O  O27  1  0.773  0.816  0.833  1.0
  O  O28  1  0.974  0.741  0.409  1.0
  O  O29  1  0.474  0.259  0.091  1.0
  O  O30  1  0.026  0.259  0.591  1.0
  O  O31  1  0.526  0.741  0.909  1.0
  O  O32  1  0.970  0.901  0.254  1.0
  O  O33  1  0.470  0.099  0.246  1.0
  O  O34  1  0.030  0.099  0.746  1.0
  O  O35  1  0.530  0.901  0.754  1.0
  O  O36  1  0.864  0.400  0.123  1.0
  O  O37  1  0.364  0.600  0.377  1.0
  O  O38  1  0.136  0.600  0.877  1.0
  O  O39  1  0.636  0.400  0.623  1.0
  O  O40  1  0.583  0.731  0.485  1.0
  O  O41  1  0.083  0.269  0.015  1.0
  O  O42  1  0.417  0.269  0.515  1.0
  O  O43  1  0.917  0.731  0.985  1.0
  O  O44  1  0.697  0.881  0.599  1.0
  O  O45  1  0.197  0.119  0.901  1.0
  O  O46  1  0.303  0.119  0.401  1.0
  O  O47  1  0.803  0.881  0.099  1.0
  O  O48  1  0.434  0.736  0.613  1.0
  O  O49  1  0.934  0.264  0.887  1.0
  O  O50  1  0.566  0.264  0.387  1.0
  O  O51  1  0.066  0.736  0.113  1.0
[/CIF]
.
The material described by Ba2Mg(PO4)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 7-coordinate geometry to one O(2), one O(4), one O(5), one O(7), one O(8), and two equivalent O(1) atoms. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(1), one O(2), one O(5), one O(6), one O(7), one O(8), and two equivalent O(3) atoms. Mg(1) is bonded to one O(2), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted MgO6 octahedra that share corners with two equivalent P(1)O4 tetrahedra, corners with two equivalent P(2)O4 tetrahedra, and  an edgeedge with one P(1)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with two equivalent Mg(1)O6 octahedra and  an edgeedge with one Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-60°. 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. The corner-sharing octahedral tilt angles range from 35-42°. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a 3-coordinate geometry to one Ba(1), one Mg(1), and one P(2) atom. In the second O site, O(5) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one P(1) atom. In the third O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Ba(2), one Mg(1), and one P(1) atom. In the fourth O site, O(7) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Mg(1), and one P(1) atom. In the fifth O site, O(8) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one P(1) atom. In the sixth O site, O(1) is bonded in a distorted single-bond geometry to one Ba(2), two equivalent Ba(1), and one P(2) atom. In the seventh O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one P(2) atom. In the eighth O site, O(3) is bonded in a distorted single-bond geometry to two equivalent Ba(2) and one P(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2Mg(PO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.864
_cell_length_b   5.321
_cell_length_c   17.013
_cell_angle_alpha   72.436
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   764.970
_cell_formula_units_Z   4
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
  Ba  Ba0  1  0.657  0.525  0.229  1.0
  Ba  Ba1  1  0.157  0.475  0.271  1.0
  Ba  Ba2  1  0.343  0.475  0.771  1.0
  Ba  Ba3  1  0.843  0.525  0.729  1.0
  Ba  Ba4  1  0.204  0.681  0.520  1.0
  Ba  Ba5  1  0.704  0.319  0.980  1.0
  Ba  Ba6  1  0.796  0.319  0.480  1.0
  Ba  Ba7  1  0.296  0.681  0.020  1.0
  Mg  Mg8  1  0.985  0.907  0.866  1.0
  Mg  Mg9  1  0.485  0.093  0.634  1.0
  Mg  Mg10  1  0.515  0.907  0.366  1.0
  Mg  Mg11  1  0.015  0.093  0.134  1.0
  P  P12  1  0.413  0.313  0.422  1.0
  P  P13  1  0.890  0.919  0.333  1.0
  P  P14  1  0.087  0.313  0.922  1.0
  P  P15  1  0.587  0.687  0.578  1.0
  P  P16  1  0.610  0.919  0.833  1.0
  P  P17  1  0.110  0.081  0.667  1.0
  P  P18  1  0.390  0.081  0.167  1.0
  P  P19  1  0.913  0.687  0.078  1.0
  O  O20  1  0.890  0.208  0.334  1.0
  O  O21  1  0.390  0.792  0.166  1.0
  O  O22  1  0.110  0.792  0.666  1.0
  O  O23  1  0.610  0.208  0.834  1.0
  O  O24  1  0.727  0.816  0.333  1.0
  O  O25  1  0.227  0.184  0.167  1.0
  O  O26  1  0.273  0.184  0.667  1.0
  O  O27  1  0.773  0.816  0.833  1.0
  O  O28  1  0.974  0.741  0.409  1.0
  O  O29  1  0.474  0.259  0.091  1.0
  O  O30  1  0.026  0.259  0.591  1.0
  O  O31  1  0.526  0.741  0.909  1.0
  O  O32  1  0.970  0.901  0.254  1.0
  O  O33  1  0.470  0.099  0.246  1.0
  O  O34  1  0.030  0.099  0.746  1.0
  O  O35  1  0.530  0.901  0.754  1.0
  O  O36  1  0.864  0.400  0.123  1.0
  O  O37  1  0.364  0.600  0.377  1.0
  O  O38  1  0.136  0.600  0.877  1.0
  O  O39  1  0.636  0.400  0.623  1.0
  O  O40  1  0.583  0.731  0.485  1.0
  O  O41  1  0.083  0.269  0.015  1.0
  O  O42  1  0.417  0.269  0.515  1.0
  O  O43  1  0.917  0.731  0.985  1.0
  O  O44  1  0.697  0.881  0.599  1.0
  O  O45  1  0.197  0.119  0.901  1.0
  O  O46  1  0.303  0.119  0.401  1.0
  O  O47  1  0.803  0.881  0.099  1.0
  O  O48  1  0.434  0.736  0.613  1.0
  O  O49  1  0.934  0.264  0.887  1.0
  O  O50  1  0.566  0.264  0.387  1.0
  O  O51  1  0.066  0.736  0.113  1.0
[/CIF]
.