The material described by Ca2Al3O8 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(4), one O(5), 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(1), one O(2), one O(3), and one O(4) atom to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(4) is bonded in a trigonal planar geometry to one Ca(2) and two equivalent Al(1) atoms. In the second O site, O(5) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one O(5) atom. In the third O site, O(1) is bonded in a trigonal planar geometry to one Ca(1), one Al(1), and one Al(2) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(2), one Al(1), and one Al(2) atom. In the fifth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Al(1) atom. is represented by the CIF file [CIF]
data_Ca2Al3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.960
_cell_length_b   7.960
_cell_length_c   12.241
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   112.693
_symmetry_Int_Tables_number   1
_cell_volume   715.599
_cell_formula_units_Z   4
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  0.674  0.326  0.500  1.0
  Ca  Ca1  1  0.174  0.826  0.000  1.0
  Ca  Ca2  1  0.326  0.674  0.500  1.0
  Ca  Ca3  1  0.826  0.174  0.000  1.0
  Ca  Ca4  1  0.305  0.305  0.846  1.0
  Ca  Ca5  1  0.695  0.695  0.154  1.0
  Ca  Ca6  1  0.195  0.195  0.346  1.0
  Ca  Ca7  1  0.805  0.805  0.654  1.0
  Al  Al8  1  0.265  0.027  0.621  1.0
  Al  Al9  1  0.973  0.735  0.379  1.0
  Al  Al10  1  0.473  0.235  0.121  1.0
  Al  Al11  1  0.765  0.527  0.879  1.0
  Al  Al12  1  0.735  0.973  0.379  1.0
  Al  Al13  1  0.027  0.265  0.621  1.0
  Al  Al14  1  0.527  0.765  0.879  1.0
  Al  Al15  1  0.235  0.473  0.121  1.0
  Al  Al16  1  0.642  0.142  0.750  1.0
  Al  Al17  1  0.858  0.358  0.250  1.0
  Al  Al18  1  0.358  0.858  0.250  1.0
  Al  Al19  1  0.142  0.642  0.750  1.0
  O  O20  1  0.724  0.293  0.863  1.0
  O  O21  1  0.707  0.276  0.137  1.0
  O  O22  1  0.207  0.776  0.363  1.0
  O  O23  1  0.224  0.793  0.637  1.0
  O  O24  1  0.276  0.707  0.137  1.0
  O  O25  1  0.293  0.724  0.863  1.0
  O  O26  1  0.793  0.224  0.637  1.0
  O  O27  1  0.776  0.207  0.363  1.0
  O  O28  1  0.431  0.154  0.717  1.0
  O  O29  1  0.846  0.569  0.283  1.0
  O  O30  1  0.346  0.069  0.217  1.0
  O  O31  1  0.931  0.654  0.783  1.0
  O  O32  1  0.569  0.846  0.283  1.0
  O  O33  1  0.154  0.431  0.717  1.0
  O  O34  1  0.654  0.931  0.783  1.0
  O  O35  1  0.069  0.346  0.217  1.0
  O  O36  1  0.356  0.109  0.488  1.0
  O  O37  1  0.891  0.644  0.512  1.0
  O  O38  1  0.391  0.144  0.988  1.0
  O  O39  1  0.856  0.609  0.012  1.0
  O  O40  1  0.644  0.891  0.512  1.0
  O  O41  1  0.109  0.356  0.488  1.0
  O  O42  1  0.609  0.856  0.012  1.0
  O  O43  1  0.144  0.391  0.988  1.0
  O  O44  1  0.064  0.064  0.648  1.0
  O  O45  1  0.936  0.936  0.352  1.0
  O  O46  1  0.436  0.436  0.148  1.0
  O  O47  1  0.564  0.564  0.852  1.0
  O  O48  1  0.030  0.030  0.950  1.0
  O  O49  1  0.970  0.970  0.050  1.0
  O  O50  1  0.470  0.470  0.450  1.0
  O  O51  1  0.530  0.530  0.550  1.0
[/CIF]
.
The material described by Ca2Al3O8 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(5) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(4), one O(5), 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(1), one O(2), one O(3), and one O(4) atom to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form corner-sharing AlO4 tetrahedra. There are five inequivalent O sites. In the first O site, O(4) is bonded in a trigonal planar geometry to one Ca(2) and two equivalent Al(1) atoms. In the second O site, O(5) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one O(5) atom. In the third O site, O(1) is bonded in a trigonal planar geometry to one Ca(1), one Al(1), and one Al(2) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ca(2), one Al(1), and one Al(2) atom. In the fifth O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to one Ca(1), one Ca(2), and one Al(1) atom. is represented by the CIF file [CIF]
data_Ca2Al3O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.960
_cell_length_b   7.960
_cell_length_c   12.241
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   112.693
_symmetry_Int_Tables_number   1
_cell_volume   715.599
_cell_formula_units_Z   4
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  0.674  0.326  0.500  1.0
  Ca  Ca1  1  0.174  0.826  0.000  1.0
  Ca  Ca2  1  0.326  0.674  0.500  1.0
  Ca  Ca3  1  0.826  0.174  0.000  1.0
  Ca  Ca4  1  0.305  0.305  0.846  1.0
  Ca  Ca5  1  0.695  0.695  0.154  1.0
  Ca  Ca6  1  0.195  0.195  0.346  1.0
  Ca  Ca7  1  0.805  0.805  0.654  1.0
  Al  Al8  1  0.265  0.027  0.621  1.0
  Al  Al9  1  0.973  0.735  0.379  1.0
  Al  Al10  1  0.473  0.235  0.121  1.0
  Al  Al11  1  0.765  0.527  0.879  1.0
  Al  Al12  1  0.735  0.973  0.379  1.0
  Al  Al13  1  0.027  0.265  0.621  1.0
  Al  Al14  1  0.527  0.765  0.879  1.0
  Al  Al15  1  0.235  0.473  0.121  1.0
  Al  Al16  1  0.642  0.142  0.750  1.0
  Al  Al17  1  0.858  0.358  0.250  1.0
  Al  Al18  1  0.358  0.858  0.250  1.0
  Al  Al19  1  0.142  0.642  0.750  1.0
  O  O20  1  0.724  0.293  0.863  1.0
  O  O21  1  0.707  0.276  0.137  1.0
  O  O22  1  0.207  0.776  0.363  1.0
  O  O23  1  0.224  0.793  0.637  1.0
  O  O24  1  0.276  0.707  0.137  1.0
  O  O25  1  0.293  0.724  0.863  1.0
  O  O26  1  0.793  0.224  0.637  1.0
  O  O27  1  0.776  0.207  0.363  1.0
  O  O28  1  0.431  0.154  0.717  1.0
  O  O29  1  0.846  0.569  0.283  1.0
  O  O30  1  0.346  0.069  0.217  1.0
  O  O31  1  0.931  0.654  0.783  1.0
  O  O32  1  0.569  0.846  0.283  1.0
  O  O33  1  0.154  0.431  0.717  1.0
  O  O34  1  0.654  0.931  0.783  1.0
  O  O35  1  0.069  0.346  0.217  1.0
  O  O36  1  0.356  0.109  0.488  1.0
  O  O37  1  0.891  0.644  0.512  1.0
  O  O38  1  0.391  0.144  0.988  1.0
  O  O39  1  0.856  0.609  0.012  1.0
  O  O40  1  0.644  0.891  0.512  1.0
  O  O41  1  0.109  0.356  0.488  1.0
  O  O42  1  0.609  0.856  0.012  1.0
  O  O43  1  0.144  0.391  0.988  1.0
  O  O44  1  0.064  0.064  0.648  1.0
  O  O45  1  0.936  0.936  0.352  1.0
  O  O46  1  0.436  0.436  0.148  1.0
  O  O47  1  0.564  0.564  0.852  1.0
  O  O48  1  0.030  0.030  0.950  1.0
  O  O49  1  0.970  0.970  0.050  1.0
  O  O50  1  0.470  0.470  0.450  1.0
  O  O51  1  0.530  0.530  0.550  1.0
[/CIF]
.