The material described by K4Na2(Si2O5)3 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one O(1), one O(5), one O(8), and two equivalent O(4) atoms to form distorted KO5 trigonal bipyramids that share  a cornercorner with one Si(3)O4 tetrahedra, corners with three equivalent 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 K(1)O5 trigonal bipyramid, and  an edgeedge with one Na(1)O5 trigonal bipyramid. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(1), one O(8), two equivalent O(2), and two equivalent O(6) atoms. Na(1) is bonded to one O(1), one O(3), one O(8), and two equivalent O(5) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent K(1)O5 trigonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra,  an edgeedge with one K(1)O5 trigonal bipyramid, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are three inequivalent Si sites. In the first Si site, Si(3) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  a cornercorner with one K(1)O5 trigonal bipyramid, and corners with two equivalent Na(1)O5 trigonal bipyramids. In the second Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent K(1)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. In the third Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(7) 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, corners with two equivalent Na(1)O5 trigonal bipyramids, and corners with three equivalent K(1)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a 4-coordinate geometry to one K(1), two equivalent Na(1), and one Si(2) atom. In the second O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2), one Si(2), and one Si(3) atom. In the third O site, O(7) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fourth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one K(2), one Na(1), and one Si(3) atom. In the fifth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent K(1), one Si(1), and one Si(2) atom. In the sixth O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Na(1), and one Si(1) atom. In the seventh O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2), one Si(1), and one Si(3) atom. In the eighth O site, O(3) is bonded in a 2-coordinate geometry to one Na(1), one Si(1), and one Si(3) atom. is represented by the CIF file [CIF]
data_K4Na2(Si2O5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.702
_cell_length_b   10.702
_cell_length_c   12.878
_cell_angle_alpha   64.071
_cell_angle_beta   64.071
_cell_angle_gamma   40.486
_symmetry_Int_Tables_number   1
_cell_volume   847.308
_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
  K  K0  1  0.437  0.688  0.334  1.0
  K  K1  1  0.312  0.563  0.166  1.0
  K  K2  1  0.563  0.312  0.666  1.0
  K  K3  1  0.688  0.437  0.834  1.0
  K  K4  1  0.926  0.575  0.165  1.0
  K  K5  1  0.425  0.074  0.335  1.0
  K  K6  1  0.074  0.425  0.835  1.0
  K  K7  1  0.575  0.926  0.665  1.0
  Na  Na8  1  0.993  0.169  0.408  1.0
  Na  Na9  1  0.831  0.007  0.092  1.0
  Na  Na10  1  0.007  0.831  0.592  1.0
  Na  Na11  1  0.169  0.993  0.908  1.0
  Si  Si12  1  0.757  0.546  0.498  1.0
  Si  Si13  1  0.454  0.243  0.002  1.0
  Si  Si14  1  0.243  0.454  0.502  1.0
  Si  Si15  1  0.546  0.757  0.998  1.0
  Si  Si16  1  0.320  0.813  0.614  1.0
  Si  Si17  1  0.187  0.680  0.886  1.0
  Si  Si18  1  0.680  0.187  0.386  1.0
  Si  Si19  1  0.813  0.320  0.114  1.0
  Si  Si20  1  0.874  0.777  0.385  1.0
  Si  Si21  1  0.223  0.126  0.115  1.0
  Si  Si22  1  0.126  0.223  0.615  1.0
  Si  Si23  1  0.777  0.874  0.885  1.0
  O  O24  1  0.756  0.531  0.381  1.0
  O  O25  1  0.469  0.244  0.119  1.0
  O  O26  1  0.244  0.469  0.619  1.0
  O  O27  1  0.531  0.756  0.881  1.0
  O  O28  1  0.771  0.699  0.482  1.0
  O  O29  1  0.301  0.229  0.018  1.0
  O  O30  1  0.229  0.301  0.518  1.0
  O  O31  1  0.699  0.771  0.982  1.0
  O  O32  1  0.943  0.327  0.561  1.0
  O  O33  1  0.673  0.057  0.939  1.0
  O  O34  1  0.057  0.673  0.439  1.0
  O  O35  1  0.327  0.943  0.061  1.0
  O  O36  1  0.563  0.614  0.603  1.0
  O  O37  1  0.386  0.437  0.897  1.0
  O  O38  1  0.437  0.386  0.397  1.0
  O  O39  1  0.614  0.563  0.103  1.0
  O  O40  1  0.226  0.858  0.521  1.0
  O  O41  1  0.142  0.774  0.979  1.0
  O  O42  1  0.774  0.142  0.479  1.0
  O  O43  1  0.858  0.226  0.021  1.0
  O  O44  1  0.299  0.990  0.601  1.0
  O  O45  1  0.010  0.701  0.899  1.0
  O  O46  1  0.701  0.010  0.399  1.0
  O  O47  1  0.990  0.299  0.101  1.0
  O  O48  1  0.231  0.769  0.750  1.0
  O  O49  1  0.769  0.231  0.250  1.0
  O  O50  1  0.931  0.752  0.254  1.0
  O  O51  1  0.248  0.069  0.246  1.0
  O  O52  1  0.069  0.248  0.746  1.0
  O  O53  1  0.752  0.931  0.754  1.0
[/CIF]
.
The material described by K4Na2(Si2O5)3 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded to one O(1), one O(5), one O(8), and two equivalent O(4) atoms to form distorted KO5 trigonal bipyramids that share  a cornercorner with one Si(3)O4 tetrahedra, corners with three equivalent 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 K(1)O5 trigonal bipyramid, and  an edgeedge with one Na(1)O5 trigonal bipyramid. In the second K site, K(2) is bonded in a 6-coordinate geometry to one O(1), one O(8), two equivalent O(2), and two equivalent O(6) atoms. Na(1) is bonded to one O(1), one O(3), one O(8), and two equivalent O(5) atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with two equivalent K(1)O5 trigonal bipyramids,  an edgeedge with one Si(1)O4 tetrahedra,  an edgeedge with one K(1)O5 trigonal bipyramid, and  an edgeedge with one Na(1)O5 trigonal bipyramid. There are three inequivalent Si sites. In the first Si site, Si(3) is bonded to one O(2), one O(3), one O(6), and one O(8) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra,  a cornercorner with one K(1)O5 trigonal bipyramid, and corners with two equivalent Na(1)O5 trigonal bipyramids. In the second Si site, Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra, corners with two equivalent Si(3)O4 tetrahedra, corners with three equivalent K(1)O5 trigonal bipyramids, and  an edgeedge with one Na(1)O5 trigonal bipyramid. In the third Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(7) 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, corners with two equivalent Na(1)O5 trigonal bipyramids, and corners with three equivalent K(1)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a 4-coordinate geometry to one K(1), two equivalent Na(1), and one Si(2) atom. In the second O site, O(6) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2), one Si(2), and one Si(3) atom. In the third O site, O(7) is bonded in a linear geometry to two equivalent Si(2) atoms. In the fourth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one K(2), one Na(1), and one Si(3) atom. In the fifth O site, O(4) is bonded in a 2-coordinate geometry to two equivalent K(1), one Si(1), and one Si(2) atom. In the sixth O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one K(2), one Na(1), and one Si(1) atom. In the seventh O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent K(2), one Si(1), and one Si(3) atom. In the eighth O site, O(3) is bonded in a 2-coordinate geometry to one Na(1), one Si(1), and one Si(3) atom. is represented by the CIF file [CIF]
data_K4Na2(Si2O5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.702
_cell_length_b   10.702
_cell_length_c   12.878
_cell_angle_alpha   64.071
_cell_angle_beta   64.071
_cell_angle_gamma   40.486
_symmetry_Int_Tables_number   1
_cell_volume   847.308
_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
  K  K0  1  0.437  0.688  0.334  1.0
  K  K1  1  0.312  0.563  0.166  1.0
  K  K2  1  0.563  0.312  0.666  1.0
  K  K3  1  0.688  0.437  0.834  1.0
  K  K4  1  0.926  0.575  0.165  1.0
  K  K5  1  0.425  0.074  0.335  1.0
  K  K6  1  0.074  0.425  0.835  1.0
  K  K7  1  0.575  0.926  0.665  1.0
  Na  Na8  1  0.993  0.169  0.408  1.0
  Na  Na9  1  0.831  0.007  0.092  1.0
  Na  Na10  1  0.007  0.831  0.592  1.0
  Na  Na11  1  0.169  0.993  0.908  1.0
  Si  Si12  1  0.757  0.546  0.498  1.0
  Si  Si13  1  0.454  0.243  0.002  1.0
  Si  Si14  1  0.243  0.454  0.502  1.0
  Si  Si15  1  0.546  0.757  0.998  1.0
  Si  Si16  1  0.320  0.813  0.614  1.0
  Si  Si17  1  0.187  0.680  0.886  1.0
  Si  Si18  1  0.680  0.187  0.386  1.0
  Si  Si19  1  0.813  0.320  0.114  1.0
  Si  Si20  1  0.874  0.777  0.385  1.0
  Si  Si21  1  0.223  0.126  0.115  1.0
  Si  Si22  1  0.126  0.223  0.615  1.0
  Si  Si23  1  0.777  0.874  0.885  1.0
  O  O24  1  0.756  0.531  0.381  1.0
  O  O25  1  0.469  0.244  0.119  1.0
  O  O26  1  0.244  0.469  0.619  1.0
  O  O27  1  0.531  0.756  0.881  1.0
  O  O28  1  0.771  0.699  0.482  1.0
  O  O29  1  0.301  0.229  0.018  1.0
  O  O30  1  0.229  0.301  0.518  1.0
  O  O31  1  0.699  0.771  0.982  1.0
  O  O32  1  0.943  0.327  0.561  1.0
  O  O33  1  0.673  0.057  0.939  1.0
  O  O34  1  0.057  0.673  0.439  1.0
  O  O35  1  0.327  0.943  0.061  1.0
  O  O36  1  0.563  0.614  0.603  1.0
  O  O37  1  0.386  0.437  0.897  1.0
  O  O38  1  0.437  0.386  0.397  1.0
  O  O39  1  0.614  0.563  0.103  1.0
  O  O40  1  0.226  0.858  0.521  1.0
  O  O41  1  0.142  0.774  0.979  1.0
  O  O42  1  0.774  0.142  0.479  1.0
  O  O43  1  0.858  0.226  0.021  1.0
  O  O44  1  0.299  0.990  0.601  1.0
  O  O45  1  0.010  0.701  0.899  1.0
  O  O46  1  0.701  0.010  0.399  1.0
  O  O47  1  0.990  0.299  0.101  1.0
  O  O48  1  0.231  0.769  0.750  1.0
  O  O49  1  0.769  0.231  0.250  1.0
  O  O50  1  0.931  0.752  0.254  1.0
  O  O51  1  0.248  0.069  0.246  1.0
  O  O52  1  0.069  0.248  0.746  1.0
  O  O53  1  0.752  0.931  0.754  1.0
[/CIF]
.