The compound described by CaAl4O7 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(2), and two 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 distorted trigonal planar geometry to one Ca(1), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1) and two equivalent Al(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_CaAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.450
_cell_length_b   7.809
_cell_length_c   7.809
_cell_angle_alpha   69.327
_cell_angle_beta   76.516
_cell_angle_gamma   76.516
_symmetry_Int_Tables_number   1
_cell_volume   298.173
_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
  Ca  Ca0  1  0.250  0.194  0.806  1.0
  Ca  Ca1  1  0.750  0.806  0.194  1.0
  Al  Al2  1  0.255  0.680  0.561  1.0
  Al  Al3  1  0.245  0.439  0.320  1.0
  Al  Al4  1  0.745  0.320  0.439  1.0
  Al  Al5  1  0.755  0.561  0.680  1.0
  Al  Al6  1  0.196  0.077  0.249  1.0
  Al  Al7  1  0.304  0.751  0.923  1.0
  Al  Al8  1  0.804  0.923  0.751  1.0
  Al  Al9  1  0.696  0.249  0.077  1.0
  O  O10  1  0.919  0.749  0.637  1.0
  O  O11  1  0.581  0.363  0.251  1.0
  O  O12  1  0.081  0.251  0.363  1.0
  O  O13  1  0.419  0.637  0.749  1.0
  O  O14  1  0.350  0.864  0.374  1.0
  O  O15  1  0.150  0.626  0.136  1.0
  O  O16  1  0.650  0.136  0.626  1.0
  O  O17  1  0.850  0.374  0.864  1.0
  O  O18  1  0.930  0.062  0.169  1.0
  O  O19  1  0.570  0.831  0.938  1.0
  O  O20  1  0.750  0.532  0.468  1.0
  O  O21  1  0.250  0.468  0.532  1.0
  O  O22  1  0.430  0.169  0.062  1.0
  O  O23  1  0.070  0.938  0.831  1.0
[/CIF]
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The compound described by CaAl4O7 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded in a 5-coordinate geometry to one O(4), two equivalent O(2), and two 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 distorted trigonal planar geometry to one Ca(1), one Al(1), and one Al(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1) and two equivalent Al(2) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_CaAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.450
_cell_length_b   7.809
_cell_length_c   7.809
_cell_angle_alpha   69.327
_cell_angle_beta   76.516
_cell_angle_gamma   76.516
_symmetry_Int_Tables_number   1
_cell_volume   298.173
_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
  Ca  Ca0  1  0.250  0.194  0.806  1.0
  Ca  Ca1  1  0.750  0.806  0.194  1.0
  Al  Al2  1  0.255  0.680  0.561  1.0
  Al  Al3  1  0.245  0.439  0.320  1.0
  Al  Al4  1  0.745  0.320  0.439  1.0
  Al  Al5  1  0.755  0.561  0.680  1.0
  Al  Al6  1  0.196  0.077  0.249  1.0
  Al  Al7  1  0.304  0.751  0.923  1.0
  Al  Al8  1  0.804  0.923  0.751  1.0
  Al  Al9  1  0.696  0.249  0.077  1.0
  O  O10  1  0.919  0.749  0.637  1.0
  O  O11  1  0.581  0.363  0.251  1.0
  O  O12  1  0.081  0.251  0.363  1.0
  O  O13  1  0.419  0.637  0.749  1.0
  O  O14  1  0.350  0.864  0.374  1.0
  O  O15  1  0.150  0.626  0.136  1.0
  O  O16  1  0.650  0.136  0.626  1.0
  O  O17  1  0.850  0.374  0.864  1.0
  O  O18  1  0.930  0.062  0.169  1.0
  O  O19  1  0.570  0.831  0.938  1.0
  O  O20  1  0.750  0.532  0.468  1.0
  O  O21  1  0.250  0.468  0.532  1.0
  O  O22  1  0.430  0.169  0.062  1.0
  O  O23  1  0.070  0.938  0.831  1.0
[/CIF]
.