The crystal structure described by Ba2As2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(1), one O(14), one O(2), one O(3), one O(8), one O(9), and two equivalent O(11) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(13), one O(14), one O(3), one O(5), one O(6), and one O(7) atom. In the fourth Ba site, Ba(4) is bonded in a 9-coordinate geometry to one O(10), one O(12), one O(14), one O(2), one O(6), one O(7), one O(8), and two equivalent O(5) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded to one O(10), one O(3), one O(4), and one O(9) atom to form corner-sharing AsO4 tetrahedra. In the second As site, As(2) is bonded to one O(11), one O(2), one O(4), and one O(8) atom to form corner-sharing AsO4 tetrahedra. In the third As site, As(3) is bonded to one O(1), one O(13), one O(14), and one O(6) atom to form corner-sharing AsO4 tetrahedra. In the fourth As site, As(4) is bonded to one O(12), one O(13), one O(5), and one O(7) atom to form corner-sharing AsO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one As(3) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Ba(1), one Ba(2), one Ba(4), and one As(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one As(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ba(2), one As(1), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(3), two equivalent Ba(4), and one As(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ba(3), one Ba(4), and one As(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(3), one Ba(4), and one As(4) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(4), and one As(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ba(2), and one As(1) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(3), one Ba(4), and one As(1) atom. In the eleventh O site, O(11) is bonded to one Ba(2), two equivalent Ba(1), and one As(2) atom to form distorted edge-sharing OBa3As tetrahedra. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(4), and one As(4) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 120 degrees geometry to one Ba(3), one As(3), and one As(4) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(3), one Ba(4), and one As(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.440
_cell_length_b   7.456
_cell_length_c   13.447
_cell_angle_alpha   93.454
_cell_angle_beta   97.193
_cell_angle_gamma   89.573
_symmetry_Int_Tables_number   1
_cell_volume   738.713
_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
  Ba  Ba0  1  0.125  0.650  0.639  1.0
  Ba  Ba1  1  0.875  0.350  0.361  1.0
  Ba  Ba2  1  0.737  0.235  0.653  1.0
  Ba  Ba3  1  0.263  0.765  0.347  1.0
  Ba  Ba4  1  0.288  0.330  0.140  1.0
  Ba  Ba5  1  0.712  0.670  0.860  1.0
  Ba  Ba6  1  0.334  0.087  0.843  1.0
  Ba  Ba7  1  0.666  0.913  0.157  1.0
  As  As8  1  0.400  0.233  0.396  1.0
  As  As9  1  0.600  0.767  0.604  1.0
  As  As10  1  0.202  0.184  0.589  1.0
  As  As11  1  0.798  0.816  0.411  1.0
  As  As12  1  0.199  0.574  0.892  1.0
  As  As13  1  0.801  0.426  0.108  1.0
  As  As14  1  0.807  0.158  0.914  1.0
  As  As15  1  0.193  0.842  0.086  1.0
  O  O16  1  0.023  0.511  0.807  1.0
  O  O17  1  0.977  0.489  0.193  1.0
  O  O18  1  0.131  0.009  0.646  1.0
  O  O19  1  0.869  0.991  0.354  1.0
  O  O20  1  0.255  0.394  0.354  1.0
  O  O21  1  0.745  0.606  0.646  1.0
  O  O22  1  0.286  0.099  0.476  1.0
  O  O23  1  0.714  0.901  0.524  1.0
  O  O24  1  0.319  1.000  0.042  1.0
  O  O25  1  0.681  0.000  0.958  1.0
  O  O26  1  0.305  0.405  0.950  1.0
  O  O27  1  0.695  0.595  0.050  1.0
  O  O28  1  0.665  0.297  0.847  1.0
  O  O29  1  0.335  0.703  0.153  1.0
  O  O30  1  0.364  0.303  0.662  1.0
  O  O31  1  0.636  0.697  0.338  1.0
  O  O32  1  0.594  0.301  0.463  1.0
  O  O33  1  0.406  0.699  0.537  1.0
  O  O34  1  0.424  0.083  0.299  1.0
  O  O35  1  0.576  0.917  0.701  1.0
  O  O36  1  0.025  0.317  0.552  1.0
  O  O37  1  0.975  0.683  0.448  1.0
  O  O38  1  0.968  0.072  0.850  1.0
  O  O39  1  0.032  0.928  0.150  1.0
  O  O40  1  0.084  0.708  0.981  1.0
  O  O41  1  0.916  0.292  0.019  1.0
  O  O42  1  0.335  0.711  0.839  1.0
  O  O43  1  0.665  0.289  0.161  1.0
[/CIF]
.
The crystal structure described by Ba2As2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(1), one O(14), one O(2), one O(3), one O(8), one O(9), and two equivalent O(11) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. In the third Ba site, Ba(3) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(13), one O(14), one O(3), one O(5), one O(6), and one O(7) atom. In the fourth Ba site, Ba(4) is bonded in a 9-coordinate geometry to one O(10), one O(12), one O(14), one O(2), one O(6), one O(7), one O(8), and two equivalent O(5) atoms. There are four inequivalent As sites. In the first As site, As(1) is bonded to one O(10), one O(3), one O(4), and one O(9) atom to form corner-sharing AsO4 tetrahedra. In the second As site, As(2) is bonded to one O(11), one O(2), one O(4), and one O(8) atom to form corner-sharing AsO4 tetrahedra. In the third As site, As(3) is bonded to one O(1), one O(13), one O(14), and one O(6) atom to form corner-sharing AsO4 tetrahedra. In the fourth As site, As(4) is bonded to one O(12), one O(13), one O(5), and one O(7) atom to form corner-sharing AsO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one As(3) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Ba(1), one Ba(2), one Ba(4), and one As(2) atom. In the third O site, O(3) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(3), and one As(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 120 degrees geometry to one Ba(2), one As(1), and one As(2) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Ba(3), two equivalent Ba(4), and one As(4) atom. In the sixth O site, O(6) is bonded in a distorted trigonal planar geometry to one Ba(3), one Ba(4), and one As(3) atom. In the seventh O site, O(7) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(3), one Ba(4), and one As(4) atom. In the eighth O site, O(8) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Ba(4), and one As(2) atom. In the ninth O site, O(9) is bonded in a distorted trigonal planar geometry to one Ba(1), one Ba(2), and one As(1) atom. In the tenth O site, O(10) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(3), one Ba(4), and one As(1) atom. In the eleventh O site, O(11) is bonded to one Ba(2), two equivalent Ba(1), and one As(2) atom to form distorted edge-sharing OBa3As tetrahedra. In the twelfth O site, O(12) is bonded in a distorted single-bond geometry to one Ba(2), one Ba(4), and one As(4) atom. In the thirteenth O site, O(13) is bonded in a distorted bent 120 degrees geometry to one Ba(3), one As(3), and one As(4) atom. In the fourteenth O site, O(14) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(3), one Ba(4), and one As(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2As2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.440
_cell_length_b   7.456
_cell_length_c   13.447
_cell_angle_alpha   93.454
_cell_angle_beta   97.193
_cell_angle_gamma   89.573
_symmetry_Int_Tables_number   1
_cell_volume   738.713
_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
  Ba  Ba0  1  0.125  0.650  0.639  1.0
  Ba  Ba1  1  0.875  0.350  0.361  1.0
  Ba  Ba2  1  0.737  0.235  0.653  1.0
  Ba  Ba3  1  0.263  0.765  0.347  1.0
  Ba  Ba4  1  0.288  0.330  0.140  1.0
  Ba  Ba5  1  0.712  0.670  0.860  1.0
  Ba  Ba6  1  0.334  0.087  0.843  1.0
  Ba  Ba7  1  0.666  0.913  0.157  1.0
  As  As8  1  0.400  0.233  0.396  1.0
  As  As9  1  0.600  0.767  0.604  1.0
  As  As10  1  0.202  0.184  0.589  1.0
  As  As11  1  0.798  0.816  0.411  1.0
  As  As12  1  0.199  0.574  0.892  1.0
  As  As13  1  0.801  0.426  0.108  1.0
  As  As14  1  0.807  0.158  0.914  1.0
  As  As15  1  0.193  0.842  0.086  1.0
  O  O16  1  0.023  0.511  0.807  1.0
  O  O17  1  0.977  0.489  0.193  1.0
  O  O18  1  0.131  0.009  0.646  1.0
  O  O19  1  0.869  0.991  0.354  1.0
  O  O20  1  0.255  0.394  0.354  1.0
  O  O21  1  0.745  0.606  0.646  1.0
  O  O22  1  0.286  0.099  0.476  1.0
  O  O23  1  0.714  0.901  0.524  1.0
  O  O24  1  0.319  1.000  0.042  1.0
  O  O25  1  0.681  0.000  0.958  1.0
  O  O26  1  0.305  0.405  0.950  1.0
  O  O27  1  0.695  0.595  0.050  1.0
  O  O28  1  0.665  0.297  0.847  1.0
  O  O29  1  0.335  0.703  0.153  1.0
  O  O30  1  0.364  0.303  0.662  1.0
  O  O31  1  0.636  0.697  0.338  1.0
  O  O32  1  0.594  0.301  0.463  1.0
  O  O33  1  0.406  0.699  0.537  1.0
  O  O34  1  0.424  0.083  0.299  1.0
  O  O35  1  0.576  0.917  0.701  1.0
  O  O36  1  0.025  0.317  0.552  1.0
  O  O37  1  0.975  0.683  0.448  1.0
  O  O38  1  0.968  0.072  0.850  1.0
  O  O39  1  0.032  0.928  0.150  1.0
  O  O40  1  0.084  0.708  0.981  1.0
  O  O41  1  0.916  0.292  0.019  1.0
  O  O42  1  0.335  0.711  0.839  1.0
  O  O43  1  0.665  0.289  0.161  1.0
[/CIF]
.