The compound described by SrAl4O7 crystallizes in the monoclinic C2/c space group. Sr(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(2), and four equivalent O(3) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(4), and two equivalent O(1) atoms to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form corner-sharing AlO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Sr(1) and two equivalent Al(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_SrAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.936
_cell_length_b   7.936
_cell_length_c   5.547
_cell_angle_alpha   76.768
_cell_angle_beta   76.768
_cell_angle_gamma   69.385
_symmetry_Int_Tables_number   1
_cell_volume   314.052
_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  0.810  0.190  0.250  1.0
  Sr  Sr1  1  0.190  0.810  0.750  1.0
  Al  Al2  1  0.562  0.681  0.235  1.0
  Al  Al3  1  0.319  0.438  0.265  1.0
  Al  Al4  1  0.438  0.319  0.765  1.0
  Al  Al5  1  0.681  0.562  0.735  1.0
  Al  Al6  1  0.255  0.082  0.205  1.0
  Al  Al7  1  0.918  0.745  0.295  1.0
  Al  Al8  1  0.745  0.918  0.795  1.0
  Al  Al9  1  0.082  0.255  0.705  1.0
  O  O10  1  0.636  0.745  0.903  1.0
  O  O11  1  0.255  0.364  0.597  1.0
  O  O12  1  0.364  0.255  0.097  1.0
  O  O13  1  0.745  0.636  0.403  1.0
  O  O14  1  0.384  0.866  0.329  1.0
  O  O15  1  0.134  0.616  0.171  1.0
  O  O16  1  0.616  0.134  0.671  1.0
  O  O17  1  0.866  0.384  0.829  1.0
  O  O18  1  0.157  0.081  0.954  1.0
  O  O19  1  0.919  0.843  0.546  1.0
  O  O20  1  0.475  0.525  0.750  1.0
  O  O21  1  0.525  0.475  0.250  1.0
  O  O22  1  0.081  0.157  0.454  1.0
  O  O23  1  0.843  0.919  0.046  1.0
[/CIF]
.
The compound described by SrAl4O7 crystallizes in the monoclinic C2/c space group. Sr(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(2), and four equivalent O(3) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(2), one O(4), and two equivalent O(1) atoms to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form corner-sharing AlO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sr(1), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Sr(1) and two equivalent Al(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Sr(1) and two equivalent Al(1) atoms. is represented by the CIF card [CIF]
data_SrAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.936
_cell_length_b   7.936
_cell_length_c   5.547
_cell_angle_alpha   76.768
_cell_angle_beta   76.768
_cell_angle_gamma   69.385
_symmetry_Int_Tables_number   1
_cell_volume   314.052
_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  0.810  0.190  0.250  1.0
  Sr  Sr1  1  0.190  0.810  0.750  1.0
  Al  Al2  1  0.562  0.681  0.235  1.0
  Al  Al3  1  0.319  0.438  0.265  1.0
  Al  Al4  1  0.438  0.319  0.765  1.0
  Al  Al5  1  0.681  0.562  0.735  1.0
  Al  Al6  1  0.255  0.082  0.205  1.0
  Al  Al7  1  0.918  0.745  0.295  1.0
  Al  Al8  1  0.745  0.918  0.795  1.0
  Al  Al9  1  0.082  0.255  0.705  1.0
  O  O10  1  0.636  0.745  0.903  1.0
  O  O11  1  0.255  0.364  0.597  1.0
  O  O12  1  0.364  0.255  0.097  1.0
  O  O13  1  0.745  0.636  0.403  1.0
  O  O14  1  0.384  0.866  0.329  1.0
  O  O15  1  0.134  0.616  0.171  1.0
  O  O16  1  0.616  0.134  0.671  1.0
  O  O17  1  0.866  0.384  0.829  1.0
  O  O18  1  0.157  0.081  0.954  1.0
  O  O19  1  0.919  0.843  0.546  1.0
  O  O20  1  0.475  0.525  0.750  1.0
  O  O21  1  0.525  0.475  0.250  1.0
  O  O22  1  0.081  0.157  0.454  1.0
  O  O23  1  0.843  0.919  0.046  1.0
[/CIF]
.