The compound described by Na2Al2(SiO4)3 crystallizes in the orthorhombic Fdd2 space group. Na(1) is bonded to one O(3), one O(4), two equivalent O(2), and two equivalent O(6) atoms to form distorted NaO6 pentagonal pyramids that share corners with two equivalent Al(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Na(1)O6 pentagonal pyramids,  an edgeedge with one Al(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with two equivalent Na(1)O6 pentagonal pyramids,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Na(1)O6 pentagonal pyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Na(1)O6 pentagonal pyramids,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Al(1)O4 tetrahedra, and  an edgeedge with one Na(1)O6 pentagonal pyramid. There are six inequivalent O sites. In the first O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(2) atom. In the second O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(2) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(6) is bonded in an L-shaped geometry to two equivalent Na(1) atoms. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the sixth O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Al(1), and one Si(2) atom. is represented by the CIF card [CIF]
data_Na2Al2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.954
_cell_length_b   9.785
_cell_length_c   9.743
_cell_angle_alpha   83.113
_cell_angle_beta   48.583
_cell_angle_gamma   48.305
_symmetry_Int_Tables_number   1
_cell_volume   567.351
_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  0.114  0.448  0.830  1.0
  Na  Na1  1  0.607  0.830  0.448  1.0
  Na  Na2  1  0.420  0.643  0.136  1.0
  Na  Na3  1  0.802  0.136  0.643  1.0
  Al  Al4  1  0.003  0.691  0.566  1.0
  Al  Al5  1  0.741  0.566  0.691  1.0
  Al  Al6  1  0.684  0.509  0.247  1.0
  Al  Al7  1  0.559  0.247  0.509  1.0
  Si  Si8  1  0.266  0.234  0.234  1.0
  Si  Si9  1  0.016  0.984  0.984  1.0
  Si  Si10  1  0.245  0.683  0.558  1.0
  Si  Si11  1  0.514  0.558  0.683  1.0
  Si  Si12  1  0.692  0.736  0.005  1.0
  Si  Si13  1  0.567  0.005  0.736  1.0
  O  O14  1  0.208  0.431  0.329  1.0
  O  O15  1  0.032  0.329  0.431  1.0
  O  O16  1  0.921  0.218  0.042  1.0
  O  O17  1  0.819  0.042  0.218  1.0
  O  O18  1  0.115  0.760  0.516  1.0
  O  O19  1  0.608  0.516  0.760  1.0
  O  O20  1  0.734  0.642  0.135  1.0
  O  O21  1  0.490  0.135  0.642  1.0
  O  O22  1  0.899  0.676  0.796  1.0
  O  O23  1  0.629  0.796  0.676  1.0
  O  O24  1  0.454  0.621  0.351  1.0
  O  O25  1  0.574  0.351  0.621  1.0
  O  O26  1  0.336  0.467  0.570  1.0
  O  O27  1  0.627  0.570  0.467  1.0
  O  O28  1  0.680  0.623  0.914  1.0
  O  O29  1  0.783  0.914  0.623  1.0
  O  O30  1  0.063  0.900  0.795  1.0
  O  O31  1  0.242  0.795  0.900  1.0
  O  O32  1  0.455  0.008  0.187  1.0
  O  O33  1  0.350  0.187  0.008  1.0
  O  O34  1  0.508  0.324  0.060  1.0
  O  O35  1  0.108  0.060  0.324  1.0
  O  O36  1  0.190  0.142  0.742  1.0
  O  O37  1  0.926  0.742  0.142  1.0
[/CIF]
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The compound described by Na2Al2(SiO4)3 crystallizes in the orthorhombic Fdd2 space group. Na(1) is bonded to one O(3), one O(4), two equivalent O(2), and two equivalent O(6) atoms to form distorted NaO6 pentagonal pyramids that share corners with two equivalent Al(1)O4 tetrahedra, corners with two equivalent Si(2)O4 tetrahedra, edges with two equivalent Na(1)O6 pentagonal pyramids,  an edgeedge with one Al(1)O4 tetrahedra, and  an edgeedge with one Si(2)O4 tetrahedra. Al(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form AlO4 tetrahedra that share corners with two equivalent Na(1)O6 pentagonal pyramids,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Na(1)O6 pentagonal pyramid. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to two equivalent O(1) and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share corners with two equivalent Na(1)O6 pentagonal pyramids,  a cornercorner with one Si(1)O4 tetrahedra, corners with three equivalent Al(1)O4 tetrahedra, and  an edgeedge with one Na(1)O6 pentagonal pyramid. There are six inequivalent O sites. In the first O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(2) atom. In the second O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Al(1), and one Si(2) atom. In the third O site, O(5) is bonded in a bent 150 degrees geometry to one Si(1) and one Si(2) atom. In the fourth O site, O(6) is bonded in an L-shaped geometry to two equivalent Na(1) atoms. In the fifth O site, O(1) is bonded in a bent 150 degrees geometry to one Al(1) and one Si(1) atom. In the sixth O site, O(2) is bonded in a 4-coordinate geometry to two equivalent Na(1), one Al(1), and one Si(2) atom. is represented by the CIF card [CIF]
data_Na2Al2(SiO4)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.954
_cell_length_b   9.785
_cell_length_c   9.743
_cell_angle_alpha   83.113
_cell_angle_beta   48.583
_cell_angle_gamma   48.305
_symmetry_Int_Tables_number   1
_cell_volume   567.351
_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  0.114  0.448  0.830  1.0
  Na  Na1  1  0.607  0.830  0.448  1.0
  Na  Na2  1  0.420  0.643  0.136  1.0
  Na  Na3  1  0.802  0.136  0.643  1.0
  Al  Al4  1  0.003  0.691  0.566  1.0
  Al  Al5  1  0.741  0.566  0.691  1.0
  Al  Al6  1  0.684  0.509  0.247  1.0
  Al  Al7  1  0.559  0.247  0.509  1.0
  Si  Si8  1  0.266  0.234  0.234  1.0
  Si  Si9  1  0.016  0.984  0.984  1.0
  Si  Si10  1  0.245  0.683  0.558  1.0
  Si  Si11  1  0.514  0.558  0.683  1.0
  Si  Si12  1  0.692  0.736  0.005  1.0
  Si  Si13  1  0.567  0.005  0.736  1.0
  O  O14  1  0.208  0.431  0.329  1.0
  O  O15  1  0.032  0.329  0.431  1.0
  O  O16  1  0.921  0.218  0.042  1.0
  O  O17  1  0.819  0.042  0.218  1.0
  O  O18  1  0.115  0.760  0.516  1.0
  O  O19  1  0.608  0.516  0.760  1.0
  O  O20  1  0.734  0.642  0.135  1.0
  O  O21  1  0.490  0.135  0.642  1.0
  O  O22  1  0.899  0.676  0.796  1.0
  O  O23  1  0.629  0.796  0.676  1.0
  O  O24  1  0.454  0.621  0.351  1.0
  O  O25  1  0.574  0.351  0.621  1.0
  O  O26  1  0.336  0.467  0.570  1.0
  O  O27  1  0.627  0.570  0.467  1.0
  O  O28  1  0.680  0.623  0.914  1.0
  O  O29  1  0.783  0.914  0.623  1.0
  O  O30  1  0.063  0.900  0.795  1.0
  O  O31  1  0.242  0.795  0.900  1.0
  O  O32  1  0.455  0.008  0.187  1.0
  O  O33  1  0.350  0.187  0.008  1.0
  O  O34  1  0.508  0.324  0.060  1.0
  O  O35  1  0.108  0.060  0.324  1.0
  O  O36  1  0.190  0.142  0.742  1.0
  O  O37  1  0.926  0.742  0.142  1.0
[/CIF]
.