The material described by Sr3Al2As4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to two equivalent As(2) and four equivalent As(1) atoms. In the second Sr site, Sr(2) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form distorted SrAs6 octahedra that share corners with four equivalent Al(1)As4 tetrahedra, edges with two equivalent Sr(2)As6 octahedra, and edges with four equivalent Al(1)As4 tetrahedra. Al(1) is bonded to two equivalent As(1) and two equivalent As(2) atoms to form AlAs4 tetrahedra that share corners with two equivalent Sr(2)As6 octahedra, corners with two equivalent Al(1)As4 tetrahedra, edges with two equivalent Sr(2)As6 octahedra, and  an edgeedge with one Al(1)As4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-56°. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Sr(2), four equivalent Sr(1), and two equivalent Al(1) atoms. In the second As site, As(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_Sr3(AlAs2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.572
_cell_length_b   8.572
_cell_length_c   6.844
_cell_angle_alpha   89.559
_cell_angle_beta   89.559
_cell_angle_gamma   75.307
_symmetry_Int_Tables_number   1
_cell_volume   486.407
_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
  Sr  Sr0  1  0.007  0.748  0.538  1.0
  Sr  Sr1  1  0.252  0.993  0.962  1.0
  Sr  Sr2  1  0.993  0.252  0.462  1.0
  Sr  Sr3  1  0.748  0.007  0.038  1.0
  Sr  Sr4  1  0.402  0.598  0.250  1.0
  Sr  Sr5  1  0.598  0.402  0.750  1.0
  Al  Al6  1  0.828  0.582  0.081  1.0
  Al  Al7  1  0.418  0.172  0.419  1.0
  Al  Al8  1  0.172  0.418  0.919  1.0
  Al  Al9  1  0.582  0.828  0.581  1.0
  As  As10  1  0.059  0.707  0.024  1.0
  As  As11  1  0.293  0.941  0.476  1.0
  As  As12  1  0.941  0.293  0.976  1.0
  As  As13  1  0.707  0.059  0.524  1.0
  As  As14  1  0.741  0.578  0.425  1.0
  As  As15  1  0.422  0.259  0.075  1.0
  As  As16  1  0.259  0.422  0.575  1.0
  As  As17  1  0.578  0.741  0.925  1.0
[/CIF]
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The material described by Sr3Al2As4 crystallizes in the monoclinic C2/c space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to two equivalent As(2) and four equivalent As(1) atoms. In the second Sr site, Sr(2) is bonded to two equivalent As(1) and four equivalent As(2) atoms to form distorted SrAs6 octahedra that share corners with four equivalent Al(1)As4 tetrahedra, edges with two equivalent Sr(2)As6 octahedra, and edges with four equivalent Al(1)As4 tetrahedra. Al(1) is bonded to two equivalent As(1) and two equivalent As(2) atoms to form AlAs4 tetrahedra that share corners with two equivalent Sr(2)As6 octahedra, corners with two equivalent Al(1)As4 tetrahedra, edges with two equivalent Sr(2)As6 octahedra, and  an edgeedge with one Al(1)As4 tetrahedra. The corner-sharing octahedral tilt angles range from 32-56°. There are two inequivalent As sites. In the first As site, As(1) is bonded in a 7-coordinate geometry to one Sr(2), four equivalent Sr(1), and two equivalent Al(1) atoms. In the second As site, As(2) is bonded in a 6-coordinate geometry to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_Sr3(AlAs2)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.572
_cell_length_b   8.572
_cell_length_c   6.844
_cell_angle_alpha   89.559
_cell_angle_beta   89.559
_cell_angle_gamma   75.307
_symmetry_Int_Tables_number   1
_cell_volume   486.407
_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
  Sr  Sr0  1  0.007  0.748  0.538  1.0
  Sr  Sr1  1  0.252  0.993  0.962  1.0
  Sr  Sr2  1  0.993  0.252  0.462  1.0
  Sr  Sr3  1  0.748  0.007  0.038  1.0
  Sr  Sr4  1  0.402  0.598  0.250  1.0
  Sr  Sr5  1  0.598  0.402  0.750  1.0
  Al  Al6  1  0.828  0.582  0.081  1.0
  Al  Al7  1  0.418  0.172  0.419  1.0
  Al  Al8  1  0.172  0.418  0.919  1.0
  Al  Al9  1  0.582  0.828  0.581  1.0
  As  As10  1  0.059  0.707  0.024  1.0
  As  As11  1  0.293  0.941  0.476  1.0
  As  As12  1  0.941  0.293  0.976  1.0
  As  As13  1  0.707  0.059  0.524  1.0
  As  As14  1  0.741  0.578  0.425  1.0
  As  As15  1  0.422  0.259  0.075  1.0
  As  As16  1  0.259  0.422  0.575  1.0
  As  As17  1  0.578  0.741  0.925  1.0
[/CIF]
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