The material described by SrAl2O4 crystallizes in the hexagonal P6_3 space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(4) atoms. In the second Sr site, Sr(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SrO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra and corners with six equivalent Al(2)O4 tetrahedra. In the third Sr site, Sr(3) is bonded in a 9-coordinate geometry to three equivalent O(4) and six equivalent O(3) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with two equivalent Sr(2)O6 octahedra and corners with four equivalent Al(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 62-70°. In the second Al site, Al(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with two equivalent Sr(2)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-76°. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(3), one Al(1), and one Al(2) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Al(1), and one Al(2) atom. In the third O site, O(2) is bonded in a distorted trigonal planar geometry to one Sr(2), one Al(1), and one Al(2) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Sr(3), one Al(1), and one Al(2) atom. is represented by the CIF file [CIF]
data_SrAl2O4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.893
_cell_length_b   8.893
_cell_length_c   8.379
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   573.844
_cell_formula_units_Z   6
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  0.667  0.333  0.280  1.0
  Sr  Sr1  1  0.333  0.667  0.780  1.0
  Sr  Sr2  1  0.667  0.333  0.743  1.0
  Sr  Sr3  1  0.333  0.667  0.243  1.0
  Sr  Sr4  1  0.000  0.000  0.761  1.0
  Sr  Sr5  1  0.000  0.000  0.261  1.0
  Al  Al6  1  0.677  0.661  0.447  1.0
  Al  Al7  1  0.016  0.677  0.947  1.0
  Al  Al8  1  0.661  0.984  0.947  1.0
  Al  Al9  1  0.339  0.016  0.447  1.0
  Al  Al10  1  0.984  0.323  0.447  1.0
  Al  Al11  1  0.323  0.339  0.947  1.0
  Al  Al12  1  0.684  0.664  0.054  1.0
  Al  Al13  1  0.020  0.684  0.554  1.0
  Al  Al14  1  0.664  0.980  0.554  1.0
  Al  Al15  1  0.336  0.020  0.054  1.0
  Al  Al16  1  0.980  0.316  0.054  1.0
  Al  Al17  1  0.316  0.336  0.554  1.0
  O  O18  1  0.542  0.449  0.519  1.0
  O  O19  1  0.093  0.542  0.019  1.0
  O  O20  1  0.449  0.907  0.019  1.0
  O  O21  1  0.551  0.093  0.519  1.0
  O  O22  1  0.907  0.458  0.519  1.0
  O  O23  1  0.458  0.551  0.019  1.0
  O  O24  1  0.208  0.790  0.438  1.0
  O  O25  1  0.418  0.208  0.938  1.0
  O  O26  1  0.790  0.582  0.938  1.0
  O  O27  1  0.210  0.418  0.438  1.0
  O  O28  1  0.582  0.792  0.438  1.0
  O  O29  1  0.792  0.210  0.938  1.0
  O  O30  1  0.889  0.120  0.538  1.0
  O  O31  1  0.769  0.889  0.038  1.0
  O  O32  1  0.120  0.231  0.038  1.0
  O  O33  1  0.880  0.769  0.538  1.0
  O  O34  1  0.231  0.111  0.538  1.0
  O  O35  1  0.111  0.880  0.038  1.0
  O  O36  1  0.273  0.367  0.751  1.0
  O  O37  1  0.906  0.273  0.251  1.0
  O  O38  1  0.367  0.094  0.251  1.0
  O  O39  1  0.633  0.906  0.751  1.0
  O  O40  1  0.094  0.727  0.751  1.0
  O  O41  1  0.727  0.633  0.251  1.0
[/CIF]
.
The material described by SrAl2O4 crystallizes in the hexagonal P6_3 space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to three equivalent O(1) and three equivalent O(4) atoms. In the second Sr site, Sr(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SrO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra and corners with six equivalent Al(2)O4 tetrahedra. In the third Sr site, Sr(3) is bonded in a 9-coordinate geometry to three equivalent O(4) and six equivalent O(3) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with two equivalent Sr(2)O6 octahedra and corners with four equivalent Al(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 62-70°. In the second Al site, Al(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with two equivalent Sr(2)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-76°. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(3), one Al(1), and one Al(2) atom. In the second O site, O(1) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), one Al(1), and one Al(2) atom. In the third O site, O(2) is bonded in a distorted trigonal planar geometry to one Sr(2), one Al(1), and one Al(2) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Sr(3), one Al(1), and one Al(2) atom. is represented by the CIF file [CIF]
data_SrAl2O4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.893
_cell_length_b   8.893
_cell_length_c   8.379
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   573.844
_cell_formula_units_Z   6
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  0.667  0.333  0.280  1.0
  Sr  Sr1  1  0.333  0.667  0.780  1.0
  Sr  Sr2  1  0.667  0.333  0.743  1.0
  Sr  Sr3  1  0.333  0.667  0.243  1.0
  Sr  Sr4  1  0.000  0.000  0.761  1.0
  Sr  Sr5  1  0.000  0.000  0.261  1.0
  Al  Al6  1  0.677  0.661  0.447  1.0
  Al  Al7  1  0.016  0.677  0.947  1.0
  Al  Al8  1  0.661  0.984  0.947  1.0
  Al  Al9  1  0.339  0.016  0.447  1.0
  Al  Al10  1  0.984  0.323  0.447  1.0
  Al  Al11  1  0.323  0.339  0.947  1.0
  Al  Al12  1  0.684  0.664  0.054  1.0
  Al  Al13  1  0.020  0.684  0.554  1.0
  Al  Al14  1  0.664  0.980  0.554  1.0
  Al  Al15  1  0.336  0.020  0.054  1.0
  Al  Al16  1  0.980  0.316  0.054  1.0
  Al  Al17  1  0.316  0.336  0.554  1.0
  O  O18  1  0.542  0.449  0.519  1.0
  O  O19  1  0.093  0.542  0.019  1.0
  O  O20  1  0.449  0.907  0.019  1.0
  O  O21  1  0.551  0.093  0.519  1.0
  O  O22  1  0.907  0.458  0.519  1.0
  O  O23  1  0.458  0.551  0.019  1.0
  O  O24  1  0.208  0.790  0.438  1.0
  O  O25  1  0.418  0.208  0.938  1.0
  O  O26  1  0.790  0.582  0.938  1.0
  O  O27  1  0.210  0.418  0.438  1.0
  O  O28  1  0.582  0.792  0.438  1.0
  O  O29  1  0.792  0.210  0.938  1.0
  O  O30  1  0.889  0.120  0.538  1.0
  O  O31  1  0.769  0.889  0.038  1.0
  O  O32  1  0.120  0.231  0.038  1.0
  O  O33  1  0.880  0.769  0.538  1.0
  O  O34  1  0.231  0.111  0.538  1.0
  O  O35  1  0.111  0.880  0.038  1.0
  O  O36  1  0.273  0.367  0.751  1.0
  O  O37  1  0.906  0.273  0.251  1.0
  O  O38  1  0.367  0.094  0.251  1.0
  O  O39  1  0.633  0.906  0.751  1.0
  O  O40  1  0.094  0.727  0.751  1.0
  O  O41  1  0.727  0.633  0.251  1.0
[/CIF]
.