The crystal structure described by Ba2TiSi2O8 crystallizes in the tetragonal P4bm space group. Ba(1) is bonded in a 10-coordinate geometry to one O(3), two equivalent O(1), three equivalent O(4), and four equivalent O(2) atoms. Ti(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted TiO5 trigonal bipyramids that share corners with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with two equivalent Ti(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to four equivalent Ba(1) and one Ti(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Ba(1) and one Si(1) atom to form a mixture of distorted corner and edge-sharing OBa3Si tetrahedra. is represented by the CIF card [CIF]
data_Ba2Ti(SiO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.561
_cell_length_b   8.561
_cell_length_c   5.240
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   384.012
_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  0.173  0.673  0.995  1.0
  Ba  Ba1  1  0.673  0.827  0.995  1.0
  Ba  Ba2  1  0.327  0.173  0.995  1.0
  Ba  Ba3  1  0.827  0.327  0.995  1.0
  Ti  Ti4  1  0.500  0.500  0.534  1.0
  Ti  Ti5  1  0.000  0.000  0.534  1.0
  Si  Si6  1  0.372  0.872  0.511  1.0
  Si  Si7  1  0.872  0.628  0.511  1.0
  Si  Si8  1  0.128  0.372  0.511  1.0
  Si  Si9  1  0.628  0.128  0.511  1.0
  O  O10  1  0.500  0.500  0.209  1.0
  O  O11  1  0.000  0.000  0.209  1.0
  O  O12  1  0.793  0.077  0.641  1.0
  O  O13  1  0.207  0.923  0.641  1.0
  O  O14  1  0.923  0.793  0.641  1.0
  O  O15  1  0.077  0.207  0.641  1.0
  O  O16  1  0.423  0.707  0.641  1.0
  O  O17  1  0.707  0.577  0.641  1.0
  O  O18  1  0.293  0.423  0.641  1.0
  O  O19  1  0.577  0.293  0.641  1.0
  O  O20  1  0.500  0.000  0.626  1.0
  O  O21  1  0.000  0.500  0.626  1.0
  O  O22  1  0.626  0.126  0.207  1.0
  O  O23  1  0.126  0.374  0.207  1.0
  O  O24  1  0.874  0.626  0.207  1.0
  O  O25  1  0.374  0.874  0.207  1.0
[/CIF]
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The crystal structure described by Ba2TiSi2O8 crystallizes in the tetragonal P4bm space group. Ba(1) is bonded in a 10-coordinate geometry to one O(3), two equivalent O(1), three equivalent O(4), and four equivalent O(2) atoms. Ti(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted TiO5 trigonal bipyramids that share corners with four equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(3), one O(4), and two equivalent O(2) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with two equivalent Ti(1)O5 trigonal bipyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to four equivalent Ba(1) and one Ti(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Ba(1), one Ti(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to two equivalent Ba(1) and two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded to three equivalent Ba(1) and one Si(1) atom to form a mixture of distorted corner and edge-sharing OBa3Si tetrahedra. is represented by the CIF card [CIF]
data_Ba2Ti(SiO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.561
_cell_length_b   8.561
_cell_length_c   5.240
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   384.012
_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  0.173  0.673  0.995  1.0
  Ba  Ba1  1  0.673  0.827  0.995  1.0
  Ba  Ba2  1  0.327  0.173  0.995  1.0
  Ba  Ba3  1  0.827  0.327  0.995  1.0
  Ti  Ti4  1  0.500  0.500  0.534  1.0
  Ti  Ti5  1  0.000  0.000  0.534  1.0
  Si  Si6  1  0.372  0.872  0.511  1.0
  Si  Si7  1  0.872  0.628  0.511  1.0
  Si  Si8  1  0.128  0.372  0.511  1.0
  Si  Si9  1  0.628  0.128  0.511  1.0
  O  O10  1  0.500  0.500  0.209  1.0
  O  O11  1  0.000  0.000  0.209  1.0
  O  O12  1  0.793  0.077  0.641  1.0
  O  O13  1  0.207  0.923  0.641  1.0
  O  O14  1  0.923  0.793  0.641  1.0
  O  O15  1  0.077  0.207  0.641  1.0
  O  O16  1  0.423  0.707  0.641  1.0
  O  O17  1  0.707  0.577  0.641  1.0
  O  O18  1  0.293  0.423  0.641  1.0
  O  O19  1  0.577  0.293  0.641  1.0
  O  O20  1  0.500  0.000  0.626  1.0
  O  O21  1  0.000  0.500  0.626  1.0
  O  O22  1  0.626  0.126  0.207  1.0
  O  O23  1  0.126  0.374  0.207  1.0
  O  O24  1  0.874  0.626  0.207  1.0
  O  O25  1  0.374  0.874  0.207  1.0
[/CIF]
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