The compound described by SrAl4O7 crystallizes in the orthorhombic Cmme space group. Sr(1) is bonded in a distorted q6 geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(2) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form AlO4 tetrahedra that share  a cornercorner with one Al(3)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra, corners with two equivalent Al(2)O4 tetrahedra, and  an edgeedge with one Al(3)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. In the second Al site, Al(2) is bonded to four equivalent O(1) atoms to form AlO4 tetrahedra that share corners with four equivalent Al(3)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. In the third Al site, Al(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of corner and edge-sharing AlO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1), one Al(1), one Al(2), and one Al(3) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Sr(1), one Al(1), and one Al(3) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Sr(1) and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_SrAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.204
_cell_length_b   8.204
_cell_length_c   4.841
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   111.301
_symmetry_Int_Tables_number   1
_cell_volume   303.534
_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  0.500  0.000  0.000  1.0
  Sr  Sr1  1  0.000  0.500  0.000  1.0
  Al  Al2  1  0.631  0.369  0.556  1.0
  Al  Al3  1  0.369  0.631  0.444  1.0
  Al  Al4  1  0.750  0.750  0.500  1.0
  Al  Al5  1  0.869  0.131  0.556  1.0
  Al  Al6  1  0.131  0.869  0.444  1.0
  Al  Al7  1  0.500  0.500  0.000  1.0
  Al  Al8  1  0.000  0.000  0.000  1.0
  Al  Al9  1  0.250  0.250  0.500  1.0
  O  O10  1  0.073  0.212  0.732  1.0
  O  O11  1  0.788  0.927  0.732  1.0
  O  O12  1  0.384  0.617  0.798  1.0
  O  O13  1  0.883  0.117  0.202  1.0
  O  O14  1  0.617  0.384  0.202  1.0
  O  O15  1  0.712  0.573  0.732  1.0
  O  O16  1  0.427  0.288  0.732  1.0
  O  O17  1  0.212  0.073  0.268  1.0
  O  O18  1  0.573  0.712  0.268  1.0
  O  O19  1  0.288  0.427  0.268  1.0
  O  O20  1  0.927  0.788  0.268  1.0
  O  O21  1  0.250  0.750  0.322  1.0
  O  O22  1  0.117  0.883  0.798  1.0
  O  O23  1  0.750  0.250  0.678  1.0
[/CIF]
.
The compound described by SrAl4O7 crystallizes in the orthorhombic Cmme space group. Sr(1) is bonded in a distorted q6 geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(2) atoms. There are three inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form AlO4 tetrahedra that share  a cornercorner with one Al(3)O6 octahedra,  a cornercorner with one Al(1)O4 tetrahedra, corners with two equivalent Al(2)O4 tetrahedra, and  an edgeedge with one Al(3)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. In the second Al site, Al(2) is bonded to four equivalent O(1) atoms to form AlO4 tetrahedra that share corners with four equivalent Al(3)O6 octahedra and corners with four equivalent Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 59°. In the third Al site, Al(3) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form a mixture of corner and edge-sharing AlO6 octahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Sr(1), one Al(1), one Al(2), and one Al(3) atom. In the second O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Sr(1), one Al(1), and one Al(3) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to two equivalent Sr(1) and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_SrAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.204
_cell_length_b   8.204
_cell_length_c   4.841
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   111.301
_symmetry_Int_Tables_number   1
_cell_volume   303.534
_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  0.500  0.000  0.000  1.0
  Sr  Sr1  1  0.000  0.500  0.000  1.0
  Al  Al2  1  0.631  0.369  0.556  1.0
  Al  Al3  1  0.369  0.631  0.444  1.0
  Al  Al4  1  0.750  0.750  0.500  1.0
  Al  Al5  1  0.869  0.131  0.556  1.0
  Al  Al6  1  0.131  0.869  0.444  1.0
  Al  Al7  1  0.500  0.500  0.000  1.0
  Al  Al8  1  0.000  0.000  0.000  1.0
  Al  Al9  1  0.250  0.250  0.500  1.0
  O  O10  1  0.073  0.212  0.732  1.0
  O  O11  1  0.788  0.927  0.732  1.0
  O  O12  1  0.384  0.617  0.798  1.0
  O  O13  1  0.883  0.117  0.202  1.0
  O  O14  1  0.617  0.384  0.202  1.0
  O  O15  1  0.712  0.573  0.732  1.0
  O  O16  1  0.427  0.288  0.732  1.0
  O  O17  1  0.212  0.073  0.268  1.0
  O  O18  1  0.573  0.712  0.268  1.0
  O  O19  1  0.288  0.427  0.268  1.0
  O  O20  1  0.927  0.788  0.268  1.0
  O  O21  1  0.250  0.750  0.322  1.0
  O  O22  1  0.117  0.883  0.798  1.0
  O  O23  1  0.750  0.250  0.678  1.0
[/CIF]
.