The material structure described by Na2BaSi2O6 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), and three equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids,  an edgeedge with one Si(2)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms. Ba(1) is bonded in a 8-coordinate geometry to one O(1), one O(6), three equivalent O(4), and three equivalent O(5) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Si(2)O4 tetrahedra and  a cornercorner with one Na(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Na(1)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Ba(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(2), three equivalent Na(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Na(2), three equivalent Ba(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Na(2), three equivalent Ba(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaNa2(SiO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.829
_cell_length_b   5.777
_cell_length_c   11.560
_cell_angle_alpha   88.559
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   322.371
_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  0.745  0.253  0.903  1.0
  Ba  Ba1  1  0.245  0.747  0.097  1.0
  Na  Na2  1  0.757  0.185  0.512  1.0
  Na  Na3  1  0.754  0.708  0.323  1.0
  Na  Na4  1  0.257  0.815  0.488  1.0
  Na  Na5  1  0.254  0.292  0.677  1.0
  Si  Si6  1  0.802  0.224  0.193  1.0
  Si  Si7  1  0.296  0.323  0.346  1.0
  Si  Si8  1  0.302  0.776  0.807  1.0
  Si  Si9  1  0.796  0.677  0.654  1.0
  O  O10  1  0.755  0.400  0.677  1.0
  O  O11  1  0.128  0.750  0.682  1.0
  O  O12  1  0.735  0.777  0.525  1.0
  O  O13  1  0.771  0.461  0.116  1.0
  O  O14  1  0.729  0.991  0.124  1.0
  O  O15  1  0.626  0.819  0.758  1.0
  O  O16  1  0.229  0.009  0.876  1.0
  O  O17  1  0.255  0.600  0.323  1.0
  O  O18  1  0.235  0.223  0.475  1.0
  O  O19  1  0.126  0.181  0.242  1.0
  O  O20  1  0.628  0.250  0.318  1.0
  O  O21  1  0.271  0.539  0.884  1.0
[/CIF]
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The material structure described by Na2BaSi2O6 crystallizes in the monoclinic P2_1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to one O(1), one O(2), and three equivalent O(3) atoms to form distorted NaO5 trigonal bipyramids that share  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, corners with two equivalent Na(1)O5 trigonal bipyramids,  an edgeedge with one Si(2)O4 tetrahedra, and edges with two equivalent Na(1)O5 trigonal bipyramids. In the second Na site, Na(2) is bonded in a 6-coordinate geometry to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms. Ba(1) is bonded in a 8-coordinate geometry to one O(1), one O(6), three equivalent O(4), and three equivalent O(5) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Si(2)O4 tetrahedra and  a cornercorner with one Na(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(2), one O(3), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Si(1)O4 tetrahedra, corners with three equivalent Na(1)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Na(2), one Ba(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Na(2), three equivalent Na(1), and one Si(2) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Na(2), three equivalent Ba(1), and one Si(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to one Na(2), three equivalent Ba(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Si(1), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_BaNa2(SiO3)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.829
_cell_length_b   5.777
_cell_length_c   11.560
_cell_angle_alpha   88.559
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   322.371
_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  0.745  0.253  0.903  1.0
  Ba  Ba1  1  0.245  0.747  0.097  1.0
  Na  Na2  1  0.757  0.185  0.512  1.0
  Na  Na3  1  0.754  0.708  0.323  1.0
  Na  Na4  1  0.257  0.815  0.488  1.0
  Na  Na5  1  0.254  0.292  0.677  1.0
  Si  Si6  1  0.802  0.224  0.193  1.0
  Si  Si7  1  0.296  0.323  0.346  1.0
  Si  Si8  1  0.302  0.776  0.807  1.0
  Si  Si9  1  0.796  0.677  0.654  1.0
  O  O10  1  0.755  0.400  0.677  1.0
  O  O11  1  0.128  0.750  0.682  1.0
  O  O12  1  0.735  0.777  0.525  1.0
  O  O13  1  0.771  0.461  0.116  1.0
  O  O14  1  0.729  0.991  0.124  1.0
  O  O15  1  0.626  0.819  0.758  1.0
  O  O16  1  0.229  0.009  0.876  1.0
  O  O17  1  0.255  0.600  0.323  1.0
  O  O18  1  0.235  0.223  0.475  1.0
  O  O19  1  0.126  0.181  0.242  1.0
  O  O20  1  0.628  0.250  0.318  1.0
  O  O21  1  0.271  0.539  0.884  1.0
[/CIF]
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