The structure described by Na2NiSi4O10 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(3), one O(7), one O(9), and two equivalent O(8) atoms. 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(6) atoms. Ni(1) is bonded to one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form NiO5 trigonal bipyramids that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and  an edgeedge with one Ni(1)O5 trigonal bipyramid. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(2), and one O(3) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Ni(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Ni(1)O5 trigonal bipyramid. In the third Si site, Si(3) is bonded to one O(2), one O(5), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Ni(1)O5 trigonal bipyramids. In the fourth Si site, Si(4) is bonded to one O(10), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Ni(1)O5 trigonal bipyramid. There are ten inequivalent O sites. In the first O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(4) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the third O site, O(2) is bonded in a 2-coordinate geometry to one Na(2), one Si(1), and one Si(3) atom. In the fourth O site, O(3) is bonded to one Na(1), one Na(2), one Ni(1), and one Si(1) atom to form distorted ONa2SiNi tetrahedra that share corners with two equivalent O(8)Na2Si2 trigonal pyramids and corners with three equivalent O(6)Na2SiNi trigonal pyramids. In the fifth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Na(2), one Ni(1), and one Si(2) atom. In the sixth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Ni(1), and one Si(3) atom. In the seventh O site, O(6) is bonded to two equivalent Na(2), one Ni(1), and one Si(4) atom to form distorted ONa2SiNi trigonal pyramids that share corners with three equivalent O(3)Na2SiNi tetrahedra,  a cornercorner with one O(8)Na2Si2 trigonal pyramid, and  an edgeedge with one O(6)Na2SiNi trigonal pyramid. In the eighth O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Si(2), and one Si(4) atom. In the ninth O site, O(8) is bonded to two equivalent Na(1), one Si(3), and one Si(4) atom to form distorted ONa2Si2 trigonal pyramids that share corners with two equivalent O(3)Na2SiNi tetrahedra,  a cornercorner with one O(6)Na2SiNi trigonal pyramid, and  an edgeedge with one O(8)Na2Si2 trigonal pyramid. In the tenth O site, O(9) is bonded in a 2-coordinate geometry to one Na(1), one Si(2), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Si4NiO10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.027
_cell_length_b   7.718
_cell_length_c   9.868
_cell_angle_alpha   101.399
_cell_angle_beta   102.741
_cell_angle_gamma   115.301
_symmetry_Int_Tables_number   1
_cell_volume   445.307
_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
  Na  Na0  1  0.342  0.244  0.023  1.0
  Na  Na1  1  0.658  0.756  0.977  1.0
  Na  Na2  1  0.742  0.274  0.419  1.0
  Na  Na3  1  0.258  0.726  0.581  1.0
  Si  Si4  1  0.761  0.061  0.805  1.0
  Si  Si5  1  0.239  0.939  0.195  1.0
  Si  Si6  1  0.916  0.291  0.141  1.0
  Si  Si7  1  0.084  0.709  0.859  1.0
  Si  Si8  1  0.603  0.359  0.740  1.0
  Si  Si9  1  0.397  0.641  0.260  1.0
  Si  Si10  1  0.186  0.380  0.750  1.0
  Si  Si11  1  0.814  0.620  0.250  1.0
  Ni  Ni12  1  0.256  0.315  0.423  1.0
  Ni  Ni13  1  0.744  0.685  0.577  1.0
  O  O14  1  0.794  0.102  0.983  1.0
  O  O15  1  0.206  0.898  0.017  1.0
  O  O16  1  0.589  0.138  0.731  1.0
  O  O17  1  0.411  0.862  0.269  1.0
  O  O18  1  0.346  0.178  0.270  1.0
  O  O19  1  0.654  0.822  0.730  1.0
  O  O20  1  0.948  0.216  0.279  1.0
  O  O21  1  0.052  0.784  0.721  1.0
  O  O22  1  0.565  0.390  0.581  1.0
  O  O23  1  0.435  0.611  0.419  1.0
  O  O24  1  0.117  0.360  0.580  1.0
  O  O25  1  0.883  0.640  0.420  1.0
  O  O26  1  0.754  0.397  0.140  1.0
  O  O27  1  0.246  0.603  0.860  1.0
  O  O28  1  0.420  0.372  0.816  1.0
  O  O29  1  0.580  0.628  0.184  1.0
  O  O30  1  0.156  0.459  0.135  1.0
  O  O31  1  0.844  0.541  0.865  1.0
  O  O32  1  0.008  0.202  0.796  1.0
  O  O33  1  0.992  0.798  0.204  1.0
[/CIF]
.
The structure described by Na2NiSi4O10 crystallizes in the triclinic P-1 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(3), one O(7), one O(9), and two equivalent O(8) atoms. 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(6) atoms. Ni(1) is bonded to one O(3), one O(4), one O(6), and two equivalent O(5) atoms to form NiO5 trigonal bipyramids that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, and  an edgeedge with one Ni(1)O5 trigonal bipyramid. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(10), one O(2), and one O(3) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Ni(1)O5 trigonal bipyramid. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and  a cornercorner with one Ni(1)O5 trigonal bipyramid. In the third Si site, Si(3) is bonded to one O(2), one O(5), one O(8), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, and corners with two equivalent Ni(1)O5 trigonal bipyramids. In the fourth Si site, Si(4) is bonded to one O(10), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(2)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and  a cornercorner with one Ni(1)O5 trigonal bipyramid. There are ten inequivalent O sites. In the first O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Na(1), one Si(1), and one Si(4) atom. In the second O site, O(1) is bonded in a 3-coordinate geometry to one Na(1), one Si(1), and one Si(2) atom. In the third O site, O(2) is bonded in a 2-coordinate geometry to one Na(2), one Si(1), and one Si(3) atom. In the fourth O site, O(3) is bonded to one Na(1), one Na(2), one Ni(1), and one Si(1) atom to form distorted ONa2SiNi tetrahedra that share corners with two equivalent O(8)Na2Si2 trigonal pyramids and corners with three equivalent O(6)Na2SiNi trigonal pyramids. In the fifth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Na(2), one Ni(1), and one Si(2) atom. In the sixth O site, O(5) is bonded in a distorted rectangular see-saw-like geometry to one Na(2), two equivalent Ni(1), and one Si(3) atom. In the seventh O site, O(6) is bonded to two equivalent Na(2), one Ni(1), and one Si(4) atom to form distorted ONa2SiNi trigonal pyramids that share corners with three equivalent O(3)Na2SiNi tetrahedra,  a cornercorner with one O(8)Na2Si2 trigonal pyramid, and  an edgeedge with one O(6)Na2SiNi trigonal pyramid. In the eighth O site, O(7) is bonded in a 3-coordinate geometry to one Na(1), one Si(2), and one Si(4) atom. In the ninth O site, O(8) is bonded to two equivalent Na(1), one Si(3), and one Si(4) atom to form distorted ONa2Si2 trigonal pyramids that share corners with two equivalent O(3)Na2SiNi tetrahedra,  a cornercorner with one O(6)Na2SiNi trigonal pyramid, and  an edgeedge with one O(8)Na2Si2 trigonal pyramid. In the tenth O site, O(9) is bonded in a 2-coordinate geometry to one Na(1), one Si(2), and one Si(3) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Si4NiO10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.027
_cell_length_b   7.718
_cell_length_c   9.868
_cell_angle_alpha   101.399
_cell_angle_beta   102.741
_cell_angle_gamma   115.301
_symmetry_Int_Tables_number   1
_cell_volume   445.307
_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
  Na  Na0  1  0.342  0.244  0.023  1.0
  Na  Na1  1  0.658  0.756  0.977  1.0
  Na  Na2  1  0.742  0.274  0.419  1.0
  Na  Na3  1  0.258  0.726  0.581  1.0
  Si  Si4  1  0.761  0.061  0.805  1.0
  Si  Si5  1  0.239  0.939  0.195  1.0
  Si  Si6  1  0.916  0.291  0.141  1.0
  Si  Si7  1  0.084  0.709  0.859  1.0
  Si  Si8  1  0.603  0.359  0.740  1.0
  Si  Si9  1  0.397  0.641  0.260  1.0
  Si  Si10  1  0.186  0.380  0.750  1.0
  Si  Si11  1  0.814  0.620  0.250  1.0
  Ni  Ni12  1  0.256  0.315  0.423  1.0
  Ni  Ni13  1  0.744  0.685  0.577  1.0
  O  O14  1  0.794  0.102  0.983  1.0
  O  O15  1  0.206  0.898  0.017  1.0
  O  O16  1  0.589  0.138  0.731  1.0
  O  O17  1  0.411  0.862  0.269  1.0
  O  O18  1  0.346  0.178  0.270  1.0
  O  O19  1  0.654  0.822  0.730  1.0
  O  O20  1  0.948  0.216  0.279  1.0
  O  O21  1  0.052  0.784  0.721  1.0
  O  O22  1  0.565  0.390  0.581  1.0
  O  O23  1  0.435  0.611  0.419  1.0
  O  O24  1  0.117  0.360  0.580  1.0
  O  O25  1  0.883  0.640  0.420  1.0
  O  O26  1  0.754  0.397  0.140  1.0
  O  O27  1  0.246  0.603  0.860  1.0
  O  O28  1  0.420  0.372  0.816  1.0
  O  O29  1  0.580  0.628  0.184  1.0
  O  O30  1  0.156  0.459  0.135  1.0
  O  O31  1  0.844  0.541  0.865  1.0
  O  O32  1  0.008  0.202  0.796  1.0
  O  O33  1  0.992  0.798  0.204  1.0
[/CIF]
.