The crystal structure described by Mg3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent As(1)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and edges with two equivalent Mg(2)O5 trigonal bipyramids. In the second Mg site, Mg(2) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form MgO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with three equivalent As(1)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one As(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 51°. As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 39-54°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2) and one As(1) atom. In the third O site, O(3) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one As(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one As(1) atom. is represented by the CIF card [CIF]
data_Mg3(AsO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.325
_cell_length_b   5.319
_cell_length_c   9.014
_cell_angle_alpha   59.652
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   344.462
_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
  Mg  Mg0  1  0.000  0.500  0.500  1.0
  Mg  Mg1  1  0.356  0.499  0.602  1.0
  Mg  Mg2  1  0.856  0.501  0.898  1.0
  Mg  Mg3  1  0.500  0.500  0.000  1.0
  Mg  Mg4  1  0.144  0.499  0.102  1.0
  Mg  Mg5  1  0.644  0.501  0.398  1.0
  As  As6  1  0.304  0.850  0.194  1.0
  As  As7  1  0.804  0.150  0.306  1.0
  As  As8  1  0.196  0.850  0.694  1.0
  As  As9  1  0.696  0.150  0.806  1.0
  O  O10  1  0.875  0.329  0.741  1.0
  O  O11  1  0.436  0.702  0.360  1.0
  O  O12  1  0.647  0.233  0.959  1.0
  O  O13  1  0.802  0.788  0.385  1.0
  O  O14  1  0.147  0.767  0.541  1.0
  O  O15  1  0.375  0.671  0.759  1.0
  O  O16  1  0.302  0.212  0.115  1.0
  O  O17  1  0.936  0.298  0.140  1.0
  O  O18  1  0.064  0.702  0.860  1.0
  O  O19  1  0.698  0.788  0.885  1.0
  O  O20  1  0.625  0.329  0.241  1.0
  O  O21  1  0.853  0.233  0.459  1.0
  O  O22  1  0.198  0.212  0.615  1.0
  O  O23  1  0.353  0.767  0.041  1.0
  O  O24  1  0.564  0.298  0.640  1.0
  O  O25  1  0.125  0.671  0.259  1.0
[/CIF]
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The crystal structure described by Mg3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form MgO6 octahedra that share corners with six equivalent As(1)O4 tetrahedra, corners with two equivalent Mg(2)O5 trigonal bipyramids, and edges with two equivalent Mg(2)O5 trigonal bipyramids. In the second Mg site, Mg(2) is bonded to one O(1), one O(3), one O(4), and two equivalent O(2) atoms to form MgO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra, corners with three equivalent As(1)O4 tetrahedra,  an edgeedge with one Mg(1)O6 octahedra,  an edgeedge with one As(1)O4 tetrahedra, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 51°. As(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AsO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra, corners with three equivalent Mg(2)O5 trigonal bipyramids, and  an edgeedge with one Mg(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 39-54°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mg(2) and one As(1) atom. In the third O site, O(3) is bonded in a T-shaped geometry to one Mg(1), one Mg(2), and one As(1) atom. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Mg(1), one Mg(2), and one As(1) atom. is represented by the CIF card [CIF]
data_Mg3(AsO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.325
_cell_length_b   5.319
_cell_length_c   9.014
_cell_angle_alpha   59.652
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   344.462
_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
  Mg  Mg0  1  0.000  0.500  0.500  1.0
  Mg  Mg1  1  0.356  0.499  0.602  1.0
  Mg  Mg2  1  0.856  0.501  0.898  1.0
  Mg  Mg3  1  0.500  0.500  0.000  1.0
  Mg  Mg4  1  0.144  0.499  0.102  1.0
  Mg  Mg5  1  0.644  0.501  0.398  1.0
  As  As6  1  0.304  0.850  0.194  1.0
  As  As7  1  0.804  0.150  0.306  1.0
  As  As8  1  0.196  0.850  0.694  1.0
  As  As9  1  0.696  0.150  0.806  1.0
  O  O10  1  0.875  0.329  0.741  1.0
  O  O11  1  0.436  0.702  0.360  1.0
  O  O12  1  0.647  0.233  0.959  1.0
  O  O13  1  0.802  0.788  0.385  1.0
  O  O14  1  0.147  0.767  0.541  1.0
  O  O15  1  0.375  0.671  0.759  1.0
  O  O16  1  0.302  0.212  0.115  1.0
  O  O17  1  0.936  0.298  0.140  1.0
  O  O18  1  0.064  0.702  0.860  1.0
  O  O19  1  0.698  0.788  0.885  1.0
  O  O20  1  0.625  0.329  0.241  1.0
  O  O21  1  0.853  0.233  0.459  1.0
  O  O22  1  0.198  0.212  0.615  1.0
  O  O23  1  0.353  0.767  0.041  1.0
  O  O24  1  0.564  0.298  0.640  1.0
  O  O25  1  0.125  0.671  0.259  1.0
[/CIF]
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