The material described by BaCu2Si2O7 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(2), and four equivalent O(3) atoms. Cu(1) is bonded in a rectangular see-saw-like geometry to one O(2), one O(3), and two equivalent O(1) atoms. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Cu(1), and one Si(1) atom. In the second O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Si(1) atoms. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Cu(1) and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ba(1), one Cu(1), and one Si(1) atom. is represented by the CIF file [CIF]
data_BaCu2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.943
_cell_length_b   7.053
_cell_length_c   13.191
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   645.931
_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  0.986  0.960  0.750  1.0
  Ba  Ba1  1  0.486  0.540  0.750  1.0
  Ba  Ba2  1  0.514  0.460  0.250  1.0
  Ba  Ba3  1  0.014  0.040  0.250  1.0
  Cu  Cu4  1  0.779  0.208  0.495  1.0
  Cu  Cu5  1  0.279  0.292  0.005  1.0
  Cu  Cu6  1  0.721  0.708  0.505  1.0
  Cu  Cu7  1  0.221  0.792  0.995  1.0
  Cu  Cu8  1  0.221  0.792  0.505  1.0
  Cu  Cu9  1  0.721  0.708  0.995  1.0
  Cu  Cu10  1  0.279  0.292  0.495  1.0
  Cu  Cu11  1  0.779  0.208  0.005  1.0
  Si  Si12  1  0.001  0.525  0.367  1.0
  Si  Si13  1  0.501  0.975  0.133  1.0
  Si  Si14  1  0.499  0.025  0.633  1.0
  Si  Si15  1  0.999  0.475  0.867  1.0
  Si  Si16  1  0.999  0.475  0.633  1.0
  Si  Si17  1  0.499  0.025  0.867  1.0
  Si  Si18  1  0.501  0.975  0.367  1.0
  Si  Si19  1  0.001  0.525  0.133  1.0
  O  O20  1  0.818  0.469  0.443  1.0
  O  O21  1  0.318  0.031  0.057  1.0
  O  O22  1  0.682  0.969  0.557  1.0
  O  O23  1  0.182  0.531  0.943  1.0
  O  O24  1  0.182  0.531  0.557  1.0
  O  O25  1  0.682  0.969  0.943  1.0
  O  O26  1  0.318  0.031  0.443  1.0
  O  O27  1  0.818  0.469  0.057  1.0
  O  O28  1  0.070  0.743  0.385  1.0
  O  O29  1  0.570  0.757  0.115  1.0
  O  O30  1  0.430  0.243  0.615  1.0
  O  O31  1  0.930  0.257  0.885  1.0
  O  O32  1  0.930  0.257  0.615  1.0
  O  O33  1  0.430  0.243  0.885  1.0
  O  O34  1  0.570  0.757  0.385  1.0
  O  O35  1  0.070  0.743  0.115  1.0
  O  O36  1  0.171  0.364  0.366  1.0
  O  O37  1  0.671  0.136  0.134  1.0
  O  O38  1  0.329  0.864  0.634  1.0
  O  O39  1  0.829  0.636  0.866  1.0
  O  O40  1  0.906  0.515  0.250  1.0
  O  O41  1  0.406  0.985  0.250  1.0
  O  O42  1  0.594  0.015  0.750  1.0
  O  O43  1  0.094  0.485  0.750  1.0
  O  O44  1  0.171  0.364  0.134  1.0
  O  O45  1  0.671  0.136  0.366  1.0
  O  O46  1  0.329  0.864  0.866  1.0
  O  O47  1  0.829  0.636  0.634  1.0
[/CIF]
.
The material described by BaCu2Si2O7 crystallizes in the orthorhombic Pnma space group. Ba(1) is bonded in a 7-coordinate geometry to one O(4), two equivalent O(2), and four equivalent O(3) atoms. Cu(1) is bonded in a rectangular see-saw-like geometry to one O(2), one O(3), and two equivalent O(1) atoms. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing SiO4 tetrahedra. There are four inequivalent O sites. In the first O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Cu(1), and one Si(1) atom. In the second O site, O(4) is bonded in a 2-coordinate geometry to one Ba(1) and two equivalent Si(1) atoms. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Cu(1) and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to one Ba(1), one Cu(1), and one Si(1) atom. is represented by the CIF file [CIF]
data_BaCu2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.943
_cell_length_b   7.053
_cell_length_c   13.191
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   645.931
_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  0.986  0.960  0.750  1.0
  Ba  Ba1  1  0.486  0.540  0.750  1.0
  Ba  Ba2  1  0.514  0.460  0.250  1.0
  Ba  Ba3  1  0.014  0.040  0.250  1.0
  Cu  Cu4  1  0.779  0.208  0.495  1.0
  Cu  Cu5  1  0.279  0.292  0.005  1.0
  Cu  Cu6  1  0.721  0.708  0.505  1.0
  Cu  Cu7  1  0.221  0.792  0.995  1.0
  Cu  Cu8  1  0.221  0.792  0.505  1.0
  Cu  Cu9  1  0.721  0.708  0.995  1.0
  Cu  Cu10  1  0.279  0.292  0.495  1.0
  Cu  Cu11  1  0.779  0.208  0.005  1.0
  Si  Si12  1  0.001  0.525  0.367  1.0
  Si  Si13  1  0.501  0.975  0.133  1.0
  Si  Si14  1  0.499  0.025  0.633  1.0
  Si  Si15  1  0.999  0.475  0.867  1.0
  Si  Si16  1  0.999  0.475  0.633  1.0
  Si  Si17  1  0.499  0.025  0.867  1.0
  Si  Si18  1  0.501  0.975  0.367  1.0
  Si  Si19  1  0.001  0.525  0.133  1.0
  O  O20  1  0.818  0.469  0.443  1.0
  O  O21  1  0.318  0.031  0.057  1.0
  O  O22  1  0.682  0.969  0.557  1.0
  O  O23  1  0.182  0.531  0.943  1.0
  O  O24  1  0.182  0.531  0.557  1.0
  O  O25  1  0.682  0.969  0.943  1.0
  O  O26  1  0.318  0.031  0.443  1.0
  O  O27  1  0.818  0.469  0.057  1.0
  O  O28  1  0.070  0.743  0.385  1.0
  O  O29  1  0.570  0.757  0.115  1.0
  O  O30  1  0.430  0.243  0.615  1.0
  O  O31  1  0.930  0.257  0.885  1.0
  O  O32  1  0.930  0.257  0.615  1.0
  O  O33  1  0.430  0.243  0.885  1.0
  O  O34  1  0.570  0.757  0.385  1.0
  O  O35  1  0.070  0.743  0.115  1.0
  O  O36  1  0.171  0.364  0.366  1.0
  O  O37  1  0.671  0.136  0.134  1.0
  O  O38  1  0.329  0.864  0.634  1.0
  O  O39  1  0.829  0.636  0.866  1.0
  O  O40  1  0.906  0.515  0.250  1.0
  O  O41  1  0.406  0.985  0.250  1.0
  O  O42  1  0.594  0.015  0.750  1.0
  O  O43  1  0.094  0.485  0.750  1.0
  O  O44  1  0.171  0.364  0.134  1.0
  O  O45  1  0.671  0.136  0.366  1.0
  O  O46  1  0.329  0.864  0.866  1.0
  O  O47  1  0.829  0.636  0.634  1.0
[/CIF]
.