The compound described by Ba2CaSi4(BO7)2 crystallizes in the tetragonal I-42m space group. Ba(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with four equivalent B(1)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. B(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form BO4 tetrahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids, corners with two equivalent B(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 pentagonal pyramid,  a cornercorner with one B(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ca(1), and two equivalent B(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one B(1), and one Si(1) atom. In the third O site, O(3) is bonded to two equivalent Ba(1), one Ca(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OBa2CaSi tetrahedra. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ba(1) and two equivalent Si(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2CaSi4(BO7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.392
_cell_length_b   9.392
_cell_length_c   9.392
_cell_angle_alpha   107.887
_cell_angle_beta   107.887
_cell_angle_gamma   112.689
_symmetry_Int_Tables_number   1
_cell_volume   636.186
_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
  Ba  Ba0  1  0.204  0.794  0.000  1.0
  Ba  Ba1  1  0.794  0.204  0.000  1.0
  Ba  Ba2  1  0.206  0.206  0.410  1.0
  Ba  Ba3  1  0.796  0.796  0.590  1.0
  Ca  Ca4  1  0.245  0.245  0.000  1.0
  Ca  Ca5  1  0.755  0.755  0.000  1.0
  Si  Si6  1  0.751  0.035  0.313  1.0
  Si  Si7  1  0.722  0.437  0.687  1.0
  Si  Si8  1  0.278  0.965  0.716  1.0
  Si  Si9  1  0.249  0.563  0.284  1.0
  Si  Si10  1  0.965  0.278  0.716  1.0
  Si  Si11  1  0.563  0.249  0.284  1.0
  Si  Si12  1  0.437  0.722  0.687  1.0
  Si  Si13  1  0.035  0.751  0.313  1.0
  B  B14  1  0.500  0.667  0.167  1.0
  B  B15  1  0.500  0.333  0.833  1.0
  B  B16  1  0.333  0.500  0.833  1.0
  B  B17  1  0.667  0.500  0.167  1.0
  O  O18  1  0.472  0.660  0.000  1.0
  O  O19  1  0.660  0.472  0.000  1.0
  O  O20  1  0.340  0.340  0.812  1.0
  O  O21  1  0.528  0.528  0.188  1.0
  O  O22  1  0.658  0.844  0.306  1.0
  O  O23  1  0.537  0.351  0.694  1.0
  O  O24  1  0.463  0.156  0.814  1.0
  O  O25  1  0.342  0.649  0.186  1.0
  O  O26  1  0.156  0.463  0.814  1.0
  O  O27  1  0.649  0.342  0.186  1.0
  O  O28  1  0.351  0.537  0.694  1.0
  O  O29  1  0.844  0.658  0.306  1.0
  O  O30  1  0.843  0.042  0.194  1.0
  O  O31  1  0.848  0.648  0.806  1.0
  O  O32  1  0.152  0.958  0.800  1.0
  O  O33  1  0.157  0.352  0.200  1.0
  O  O34  1  0.958  0.152  0.800  1.0
  O  O35  1  0.352  0.157  0.200  1.0
  O  O36  1  0.648  0.848  0.806  1.0
  O  O37  1  0.042  0.843  0.194  1.0
  O  O38  1  0.912  0.178  0.513  1.0
  O  O39  1  0.665  0.399  0.487  1.0
  O  O40  1  0.335  0.822  0.734  1.0
  O  O41  1  0.088  0.601  0.266  1.0
  O  O42  1  0.822  0.335  0.734  1.0
  O  O43  1  0.601  0.088  0.266  1.0
  O  O44  1  0.399  0.665  0.487  1.0
  O  O45  1  0.178  0.912  0.513  1.0
[/CIF]
.
The compound described by Ba2CaSi4(BO7)2 crystallizes in the tetragonal I-42m space group. Ba(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. Ca(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form distorted CaO6 pentagonal pyramids that share corners with four equivalent B(1)O4 tetrahedra and corners with four equivalent Si(1)O4 tetrahedra. B(1) is bonded to two equivalent O(1) and two equivalent O(2) atoms to form BO4 tetrahedra that share corners with two equivalent Ca(1)O6 pentagonal pyramids, corners with two equivalent B(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 pentagonal pyramid,  a cornercorner with one B(1)O4 tetrahedra, and corners with two equivalent Si(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Ca(1), and two equivalent B(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Ba(1), one B(1), and one Si(1) atom. In the third O site, O(3) is bonded to two equivalent Ba(1), one Ca(1), and one Si(1) atom to form a mixture of distorted edge and corner-sharing OBa2CaSi tetrahedra. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Ba(1) and two equivalent Si(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba2CaSi4(BO7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.392
_cell_length_b   9.392
_cell_length_c   9.392
_cell_angle_alpha   107.887
_cell_angle_beta   107.887
_cell_angle_gamma   112.689
_symmetry_Int_Tables_number   1
_cell_volume   636.186
_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
  Ba  Ba0  1  0.204  0.794  0.000  1.0
  Ba  Ba1  1  0.794  0.204  0.000  1.0
  Ba  Ba2  1  0.206  0.206  0.410  1.0
  Ba  Ba3  1  0.796  0.796  0.590  1.0
  Ca  Ca4  1  0.245  0.245  0.000  1.0
  Ca  Ca5  1  0.755  0.755  0.000  1.0
  Si  Si6  1  0.751  0.035  0.313  1.0
  Si  Si7  1  0.722  0.437  0.687  1.0
  Si  Si8  1  0.278  0.965  0.716  1.0
  Si  Si9  1  0.249  0.563  0.284  1.0
  Si  Si10  1  0.965  0.278  0.716  1.0
  Si  Si11  1  0.563  0.249  0.284  1.0
  Si  Si12  1  0.437  0.722  0.687  1.0
  Si  Si13  1  0.035  0.751  0.313  1.0
  B  B14  1  0.500  0.667  0.167  1.0
  B  B15  1  0.500  0.333  0.833  1.0
  B  B16  1  0.333  0.500  0.833  1.0
  B  B17  1  0.667  0.500  0.167  1.0
  O  O18  1  0.472  0.660  0.000  1.0
  O  O19  1  0.660  0.472  0.000  1.0
  O  O20  1  0.340  0.340  0.812  1.0
  O  O21  1  0.528  0.528  0.188  1.0
  O  O22  1  0.658  0.844  0.306  1.0
  O  O23  1  0.537  0.351  0.694  1.0
  O  O24  1  0.463  0.156  0.814  1.0
  O  O25  1  0.342  0.649  0.186  1.0
  O  O26  1  0.156  0.463  0.814  1.0
  O  O27  1  0.649  0.342  0.186  1.0
  O  O28  1  0.351  0.537  0.694  1.0
  O  O29  1  0.844  0.658  0.306  1.0
  O  O30  1  0.843  0.042  0.194  1.0
  O  O31  1  0.848  0.648  0.806  1.0
  O  O32  1  0.152  0.958  0.800  1.0
  O  O33  1  0.157  0.352  0.200  1.0
  O  O34  1  0.958  0.152  0.800  1.0
  O  O35  1  0.352  0.157  0.200  1.0
  O  O36  1  0.648  0.848  0.806  1.0
  O  O37  1  0.042  0.843  0.194  1.0
  O  O38  1  0.912  0.178  0.513  1.0
  O  O39  1  0.665  0.399  0.487  1.0
  O  O40  1  0.335  0.822  0.734  1.0
  O  O41  1  0.088  0.601  0.266  1.0
  O  O42  1  0.822  0.335  0.734  1.0
  O  O43  1  0.601  0.088  0.266  1.0
  O  O44  1  0.399  0.665  0.487  1.0
  O  O45  1  0.178  0.912  0.513  1.0
[/CIF]
.