The compound described by Cd3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(8) atoms to form distorted CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra,  a cornercorner with one Cd(2)O5 trigonal bipyramid, and edges with two equivalent Cd(1)O5 trigonal bipyramids. In the second Cd site, Cd(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra, and  a cornercorner with one Cd(1)O5 trigonal bipyramid. In the third Cd site, Cd(3) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(5), one O(7), and two equivalent O(6) atoms. There are two inequivalent As sites. In the first As site, 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 Cd(1)O5 trigonal bipyramids and corners with three equivalent Cd(2)O5 trigonal bipyramids. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Cd(1)O5 trigonal bipyramids and corners with two equivalent Cd(2)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Cd(1) and one As(1) atom. In the second O site, O(5) is bonded in a distorted trigonal planar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the third O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Cd(3) and one As(2) atom. In the fourth O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the fifth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cd(1) and one As(2) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Cd(1), one Cd(2), and one As(1) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to one Cd(2), one Cd(3), and one As(1) atom. In the eighth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(1) atom. is represented by the CIF file [CIF]
data_Cd3(AsO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.080
_cell_length_b   6.658
_cell_length_c   9.289
_cell_angle_alpha   81.671
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   739.149
_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
  Cd  Cd0  1  0.692  0.369  0.356  1.0
  Cd  Cd1  1  0.192  0.131  0.644  1.0
  Cd  Cd2  1  0.308  0.631  0.644  1.0
  Cd  Cd3  1  0.808  0.869  0.356  1.0
  Cd  Cd4  1  0.581  0.166  0.718  1.0
  Cd  Cd5  1  0.081  0.334  0.282  1.0
  Cd  Cd6  1  0.419  0.834  0.282  1.0
  Cd  Cd7  1  0.919  0.666  0.718  1.0
  Cd  Cd8  1  0.617  0.656  0.950  1.0
  Cd  Cd9  1  0.117  0.844  0.050  1.0
  Cd  Cd10  1  0.383  0.344  0.050  1.0
  Cd  Cd11  1  0.883  0.156  0.950  1.0
  As  As12  1  0.588  0.687  0.607  1.0
  As  As13  1  0.088  0.813  0.393  1.0
  As  As14  1  0.412  0.313  0.393  1.0
  As  As15  1  0.912  0.187  0.607  1.0
  As  As16  1  0.637  0.108  0.082  1.0
  As  As17  1  0.137  0.392  0.918  1.0
  As  As18  1  0.363  0.892  0.918  1.0
  As  As19  1  0.863  0.608  0.082  1.0
  O  O20  1  0.462  0.753  0.530  1.0
  O  O21  1  0.962  0.747  0.470  1.0
  O  O22  1  0.538  0.247  0.470  1.0
  O  O23  1  0.038  0.253  0.530  1.0
  O  O24  1  0.576  0.482  0.737  1.0
  O  O25  1  0.076  0.018  0.263  1.0
  O  O26  1  0.424  0.518  0.263  1.0
  O  O27  1  0.924  0.982  0.737  1.0
  O  O28  1  0.635  0.862  0.708  1.0
  O  O29  1  0.135  0.638  0.292  1.0
  O  O30  1  0.365  0.138  0.292  1.0
  O  O31  1  0.865  0.362  0.708  1.0
  O  O32  1  0.682  0.654  0.477  1.0
  O  O33  1  0.182  0.846  0.523  1.0
  O  O34  1  0.318  0.346  0.523  1.0
  O  O35  1  0.818  0.154  0.477  1.0
  O  O36  1  0.562  0.891  0.120  1.0
  O  O37  1  0.062  0.609  0.880  1.0
  O  O38  1  0.438  0.109  0.880  1.0
  O  O39  1  0.938  0.391  0.120  1.0
  O  O40  1  0.933  0.831  0.080  1.0
  O  O41  1  0.433  0.669  0.920  1.0
  O  O42  1  0.067  0.169  0.920  1.0
  O  O43  1  0.567  0.331  0.080  1.0
  O  O44  1  0.796  0.598  0.922  1.0
  O  O45  1  0.296  0.902  0.078  1.0
  O  O46  1  0.204  0.402  0.078  1.0
  O  O47  1  0.704  0.098  0.922  1.0
  O  O48  1  0.765  0.625  0.211  1.0
  O  O49  1  0.265  0.875  0.789  1.0
  O  O50  1  0.235  0.375  0.789  1.0
  O  O51  1  0.735  0.125  0.211  1.0
[/CIF]
.
The compound described by Cd3(AsO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Cd sites. In the first Cd site, Cd(1) is bonded to one O(1), two equivalent O(4), and two equivalent O(8) atoms to form distorted CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra,  a cornercorner with one Cd(2)O5 trigonal bipyramid, and edges with two equivalent Cd(1)O5 trigonal bipyramids. In the second Cd site, Cd(2) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(7) atom to form CdO5 trigonal bipyramids that share corners with two equivalent As(2)O4 tetrahedra, corners with three equivalent As(1)O4 tetrahedra, and  a cornercorner with one Cd(1)O5 trigonal bipyramid. In the third Cd site, Cd(3) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(5), one O(7), and two equivalent O(6) atoms. There are two inequivalent As sites. In the first As site, 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 Cd(1)O5 trigonal bipyramids and corners with three equivalent Cd(2)O5 trigonal bipyramids. In the second As site, As(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form AsO4 tetrahedra that share corners with two equivalent Cd(1)O5 trigonal bipyramids and corners with two equivalent Cd(2)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Cd(1) and one As(1) atom. In the second O site, O(5) is bonded in a distorted trigonal planar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the third O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Cd(3) and one As(2) atom. In the fourth O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(2) atom. In the fifth O site, O(8) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Cd(1) and one As(2) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Cd(1), one Cd(2), and one As(1) atom. In the seventh O site, O(2) is bonded in a 3-coordinate geometry to one Cd(2), one Cd(3), and one As(1) atom. In the eighth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Cd(2), one Cd(3), and one As(1) atom. is represented by the CIF file [CIF]
data_Cd3(AsO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.080
_cell_length_b   6.658
_cell_length_c   9.289
_cell_angle_alpha   81.671
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   739.149
_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
  Cd  Cd0  1  0.692  0.369  0.356  1.0
  Cd  Cd1  1  0.192  0.131  0.644  1.0
  Cd  Cd2  1  0.308  0.631  0.644  1.0
  Cd  Cd3  1  0.808  0.869  0.356  1.0
  Cd  Cd4  1  0.581  0.166  0.718  1.0
  Cd  Cd5  1  0.081  0.334  0.282  1.0
  Cd  Cd6  1  0.419  0.834  0.282  1.0
  Cd  Cd7  1  0.919  0.666  0.718  1.0
  Cd  Cd8  1  0.617  0.656  0.950  1.0
  Cd  Cd9  1  0.117  0.844  0.050  1.0
  Cd  Cd10  1  0.383  0.344  0.050  1.0
  Cd  Cd11  1  0.883  0.156  0.950  1.0
  As  As12  1  0.588  0.687  0.607  1.0
  As  As13  1  0.088  0.813  0.393  1.0
  As  As14  1  0.412  0.313  0.393  1.0
  As  As15  1  0.912  0.187  0.607  1.0
  As  As16  1  0.637  0.108  0.082  1.0
  As  As17  1  0.137  0.392  0.918  1.0
  As  As18  1  0.363  0.892  0.918  1.0
  As  As19  1  0.863  0.608  0.082  1.0
  O  O20  1  0.462  0.753  0.530  1.0
  O  O21  1  0.962  0.747  0.470  1.0
  O  O22  1  0.538  0.247  0.470  1.0
  O  O23  1  0.038  0.253  0.530  1.0
  O  O24  1  0.576  0.482  0.737  1.0
  O  O25  1  0.076  0.018  0.263  1.0
  O  O26  1  0.424  0.518  0.263  1.0
  O  O27  1  0.924  0.982  0.737  1.0
  O  O28  1  0.635  0.862  0.708  1.0
  O  O29  1  0.135  0.638  0.292  1.0
  O  O30  1  0.365  0.138  0.292  1.0
  O  O31  1  0.865  0.362  0.708  1.0
  O  O32  1  0.682  0.654  0.477  1.0
  O  O33  1  0.182  0.846  0.523  1.0
  O  O34  1  0.318  0.346  0.523  1.0
  O  O35  1  0.818  0.154  0.477  1.0
  O  O36  1  0.562  0.891  0.120  1.0
  O  O37  1  0.062  0.609  0.880  1.0
  O  O38  1  0.438  0.109  0.880  1.0
  O  O39  1  0.938  0.391  0.120  1.0
  O  O40  1  0.933  0.831  0.080  1.0
  O  O41  1  0.433  0.669  0.920  1.0
  O  O42  1  0.067  0.169  0.920  1.0
  O  O43  1  0.567  0.331  0.080  1.0
  O  O44  1  0.796  0.598  0.922  1.0
  O  O45  1  0.296  0.902  0.078  1.0
  O  O46  1  0.204  0.402  0.078  1.0
  O  O47  1  0.704  0.098  0.922  1.0
  O  O48  1  0.765  0.625  0.211  1.0
  O  O49  1  0.265  0.875  0.789  1.0
  O  O50  1  0.235  0.375  0.789  1.0
  O  O51  1  0.735  0.125  0.211  1.0
[/CIF]
.