The crystal structure described by K2Al2O7 crystallizes in the orthorhombic Aea2 space group. K(1) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. 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. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to four equivalent K(1) and one Al(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one Al(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent K(1) and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_K2Al2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.769
_cell_length_b   6.769
_cell_length_c   8.015
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   103.976
_symmetry_Int_Tables_number   1
_cell_volume   356.398
_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
  K  K0  1  0.511  0.530  0.724  1.0
  K  K1  1  0.470  0.489  0.276  1.0
  K  K2  1  0.011  0.030  0.776  1.0
  K  K3  1  0.970  0.989  0.224  1.0
  Al  Al4  1  0.068  0.545  0.008  1.0
  Al  Al5  1  0.455  0.932  0.992  1.0
  Al  Al6  1  0.568  0.045  0.492  1.0
  Al  Al7  1  0.955  0.432  0.508  1.0
  O  O8  1  0.168  0.335  0.518  1.0
  O  O9  1  0.665  0.832  0.482  1.0
  O  O10  1  0.668  0.835  0.982  1.0
  O  O11  1  0.165  0.332  0.018  1.0
  O  O12  1  0.918  0.479  0.813  1.0
  O  O13  1  0.521  0.082  0.187  1.0
  O  O14  1  0.418  0.979  0.687  1.0
  O  O15  1  0.021  0.582  0.313  1.0
  O  O16  1  0.977  0.620  0.680  1.0
  O  O17  1  0.380  0.023  0.320  1.0
  O  O18  1  0.477  0.120  0.820  1.0
  O  O19  1  0.880  0.523  0.180  1.0
  O  O20  1  0.708  0.292  0.500  1.0
  O  O21  1  0.208  0.792  0.000  1.0
[/CIF]
.
The crystal structure described by K2Al2O7 crystallizes in the orthorhombic Aea2 space group. K(1) is bonded in a 9-coordinate geometry to one O(4), two equivalent O(2), two equivalent O(3), and four equivalent O(1) atoms. 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. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to four equivalent K(1) and one Al(1) atom. In the second O site, O(2) is bonded in a distorted single-bond geometry to two equivalent K(1) and one Al(1) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to two equivalent K(1) and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Al(1) atoms. is represented by the CIF file [CIF]
data_K2Al2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.769
_cell_length_b   6.769
_cell_length_c   8.015
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   103.976
_symmetry_Int_Tables_number   1
_cell_volume   356.398
_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
  K  K0  1  0.511  0.530  0.724  1.0
  K  K1  1  0.470  0.489  0.276  1.0
  K  K2  1  0.011  0.030  0.776  1.0
  K  K3  1  0.970  0.989  0.224  1.0
  Al  Al4  1  0.068  0.545  0.008  1.0
  Al  Al5  1  0.455  0.932  0.992  1.0
  Al  Al6  1  0.568  0.045  0.492  1.0
  Al  Al7  1  0.955  0.432  0.508  1.0
  O  O8  1  0.168  0.335  0.518  1.0
  O  O9  1  0.665  0.832  0.482  1.0
  O  O10  1  0.668  0.835  0.982  1.0
  O  O11  1  0.165  0.332  0.018  1.0
  O  O12  1  0.918  0.479  0.813  1.0
  O  O13  1  0.521  0.082  0.187  1.0
  O  O14  1  0.418  0.979  0.687  1.0
  O  O15  1  0.021  0.582  0.313  1.0
  O  O16  1  0.977  0.620  0.680  1.0
  O  O17  1  0.380  0.023  0.320  1.0
  O  O18  1  0.477  0.120  0.820  1.0
  O  O19  1  0.880  0.523  0.180  1.0
  O  O20  1  0.708  0.292  0.500  1.0
  O  O21  1  0.208  0.792  0.000  1.0
[/CIF]
.