The material structure described by Na2Al2B2O7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 9-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), and three equivalent O(1) atoms. 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 three equivalent Na(1)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 66-68°. B(1) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Na(2) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), one Al(1), and one B(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), one Al(1), and one B(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Al(1), and one B(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Al2B2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   15.590
_cell_length_b   4.870
_cell_length_c   4.875
_cell_angle_alpha   60.111
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   320.938
_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  0.500  0.000  0.000  1.0
  Na  Na1  1  0.000  0.000  0.000  1.0
  Na  Na2  1  0.750  0.006  0.005  1.0
  Na  Na3  1  0.250  0.994  0.995  1.0
  Al  Al4  1  0.139  0.342  0.329  1.0
  Al  Al5  1  0.639  0.658  0.671  1.0
  Al  Al6  1  0.861  0.658  0.671  1.0
  Al  Al7  1  0.361  0.342  0.329  1.0
  B  B8  1  0.605  0.331  0.334  1.0
  B  B9  1  0.105  0.669  0.666  1.0
  B  B10  1  0.395  0.669  0.666  1.0
  B  B11  1  0.895  0.331  0.334  1.0
  O  O12  1  0.750  0.632  0.683  1.0
  O  O13  1  0.250  0.368  0.317  1.0
  O  O14  1  0.400  0.647  0.395  1.0
  O  O15  1  0.397  0.397  0.960  1.0
  O  O16  1  0.390  0.963  0.646  1.0
  O  O17  1  0.900  0.353  0.605  1.0
  O  O18  1  0.897  0.603  0.040  1.0
  O  O19  1  0.890  0.037  0.354  1.0
  O  O20  1  0.600  0.353  0.605  1.0
  O  O21  1  0.603  0.603  0.040  1.0
  O  O22  1  0.610  0.037  0.354  1.0
  O  O23  1  0.100  0.647  0.395  1.0
  O  O24  1  0.103  0.397  0.960  1.0
  O  O25  1  0.110  0.963  0.646  1.0
[/CIF]
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The material structure described by Na2Al2B2O7 crystallizes in the monoclinic P2_1/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with six equivalent Al(1)O4 tetrahedra. In the second Na site, Na(2) is bonded in a 9-coordinate geometry to two equivalent O(2), two equivalent O(3), two equivalent O(4), and three equivalent O(1) atoms. 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 three equivalent Na(1)O6 octahedra and  a cornercorner with one Al(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 66-68°. B(1) is bonded in a trigonal planar geometry to one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to three equivalent Na(2) and two equivalent Al(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), one Al(1), and one B(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), one Al(1), and one B(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Al(1), and one B(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Na2Al2B2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   15.590
_cell_length_b   4.870
_cell_length_c   4.875
_cell_angle_alpha   60.111
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   320.938
_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  0.500  0.000  0.000  1.0
  Na  Na1  1  0.000  0.000  0.000  1.0
  Na  Na2  1  0.750  0.006  0.005  1.0
  Na  Na3  1  0.250  0.994  0.995  1.0
  Al  Al4  1  0.139  0.342  0.329  1.0
  Al  Al5  1  0.639  0.658  0.671  1.0
  Al  Al6  1  0.861  0.658  0.671  1.0
  Al  Al7  1  0.361  0.342  0.329  1.0
  B  B8  1  0.605  0.331  0.334  1.0
  B  B9  1  0.105  0.669  0.666  1.0
  B  B10  1  0.395  0.669  0.666  1.0
  B  B11  1  0.895  0.331  0.334  1.0
  O  O12  1  0.750  0.632  0.683  1.0
  O  O13  1  0.250  0.368  0.317  1.0
  O  O14  1  0.400  0.647  0.395  1.0
  O  O15  1  0.397  0.397  0.960  1.0
  O  O16  1  0.390  0.963  0.646  1.0
  O  O17  1  0.900  0.353  0.605  1.0
  O  O18  1  0.897  0.603  0.040  1.0
  O  O19  1  0.890  0.037  0.354  1.0
  O  O20  1  0.600  0.353  0.605  1.0
  O  O21  1  0.603  0.603  0.040  1.0
  O  O22  1  0.610  0.037  0.354  1.0
  O  O23  1  0.100  0.647  0.395  1.0
  O  O24  1  0.103  0.397  0.960  1.0
  O  O25  1  0.110  0.963  0.646  1.0
[/CIF]
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