The structure described by Y2Al(BeB)O7 crystallizes in the orthorhombic P2_12_12_1 space group. Be(1) is bonded to one O(3), one O(5), one O(6), and one O(7) atom to form distorted BeO4 trigonal pyramids that share  a cornercorner with one Al(1)O5 trigonal bipyramid and  an edgeedge with one Al(1)O5 trigonal bipyramid. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. In the second Y site, Y(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. Al(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form AlO5 trigonal bipyramids that share  a cornercorner with one Be(1)O4 trigonal pyramid and  an edgeedge with one Be(1)O4 trigonal pyramid. B(1) is bonded in a trigonal planar geometry to one O(1), one O(6), and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Y(1), one Y(2), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Be(1), one Y(1), one Y(2), and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Y(1), one Y(2), and one Al(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Be(1), one Y(1), and one Al(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Be(1), one Y(1), and one B(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Be(1), one Y(2), one Al(1), and one B(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2BeAlBO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.405
_cell_length_b   7.520
_cell_length_c   10.065
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   560.434
_cell_formula_units_Z   4
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
  Y  Y0  1  0.072  0.282  0.105  1.0
  Y  Y1  1  0.502  0.774  0.269  1.0
  Y  Y2  1  0.928  0.782  0.395  1.0
  Y  Y3  1  0.498  0.274  0.231  1.0
  Y  Y4  1  0.998  0.226  0.769  1.0
  Y  Y5  1  0.428  0.718  0.605  1.0
  Y  Y6  1  0.002  0.726  0.731  1.0
  Y  Y7  1  0.572  0.218  0.895  1.0
  Be  Be8  1  0.416  0.859  0.886  1.0
  Be  Be9  1  0.584  0.359  0.614  1.0
  Be  Be10  1  0.084  0.141  0.386  1.0
  Be  Be11  1  0.916  0.641  0.114  1.0
  Al  Al12  1  0.765  0.921  0.013  1.0
  Al  Al13  1  0.735  0.079  0.513  1.0
  Al  Al14  1  0.235  0.421  0.487  1.0
  Al  Al15  1  0.265  0.579  0.987  1.0
  B  B16  1  0.825  0.530  0.940  1.0
  B  B17  1  0.175  0.030  0.560  1.0
  B  B18  1  0.675  0.470  0.440  1.0
  B  B19  1  0.325  0.970  0.060  1.0
  O  O20  1  0.724  0.543  0.323  1.0
  O  O21  1  0.415  0.406  0.049  1.0
  O  O22  1  0.801  0.801  0.172  1.0
  O  O23  1  0.620  0.088  0.097  1.0
  O  O24  1  0.116  0.588  0.137  1.0
  O  O25  1  0.309  0.047  0.936  1.0
  O  O26  1  0.892  0.709  0.945  1.0
  O  O27  1  0.108  0.209  0.555  1.0
  O  O28  1  0.691  0.547  0.564  1.0
  O  O29  1  0.884  0.088  0.363  1.0
  O  O30  1  0.380  0.588  0.403  1.0
  O  O31  1  0.199  0.301  0.328  1.0
  O  O32  1  0.585  0.906  0.451  1.0
  O  O33  1  0.276  0.043  0.177  1.0
  O  O34  1  0.776  0.457  0.823  1.0
  O  O35  1  0.384  0.412  0.637  1.0
  O  O36  1  0.880  0.912  0.597  1.0
  O  O37  1  0.699  0.199  0.672  1.0
  O  O38  1  0.085  0.594  0.549  1.0
  O  O39  1  0.608  0.291  0.445  1.0
  O  O40  1  0.191  0.953  0.436  1.0
  O  O41  1  0.392  0.791  0.055  1.0
  O  O42  1  0.809  0.453  0.064  1.0
  O  O43  1  0.915  0.094  0.951  1.0
  O  O44  1  0.301  0.699  0.828  1.0
  O  O45  1  0.120  0.412  0.903  1.0
  O  O46  1  0.616  0.912  0.863  1.0
  O  O47  1  0.224  0.957  0.677  1.0
[/CIF]
.
The structure described by Y2Al(BeB)O7 crystallizes in the orthorhombic P2_12_12_1 space group. Be(1) is bonded to one O(3), one O(5), one O(6), and one O(7) atom to form distorted BeO4 trigonal pyramids that share  a cornercorner with one Al(1)O5 trigonal bipyramid and  an edgeedge with one Al(1)O5 trigonal bipyramid. There are two inequivalent Y sites. In the first Y site, Y(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(4), one O(5), one O(6), and two equivalent O(2) atoms. In the second Y site, Y(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and one O(7) atom. Al(1) is bonded to one O(2), one O(3), one O(4), one O(5), and one O(7) atom to form AlO5 trigonal bipyramids that share  a cornercorner with one Be(1)O4 trigonal pyramid and  an edgeedge with one Be(1)O4 trigonal pyramid. B(1) is bonded in a trigonal planar geometry to one O(1), one O(6), and one O(7) atom. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Y(1), one Y(2), and one B(1) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Y(2), two equivalent Y(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Be(1), one Y(1), one Y(2), and one Al(1) atom. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Y(1), one Y(2), and one Al(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Be(1), one Y(1), and one Al(1) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one Be(1), one Y(1), and one B(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Be(1), one Y(2), one Al(1), and one B(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Y2BeAlBO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.405
_cell_length_b   7.520
_cell_length_c   10.065
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   560.434
_cell_formula_units_Z   4
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
  Y  Y0  1  0.072  0.282  0.105  1.0
  Y  Y1  1  0.502  0.774  0.269  1.0
  Y  Y2  1  0.928  0.782  0.395  1.0
  Y  Y3  1  0.498  0.274  0.231  1.0
  Y  Y4  1  0.998  0.226  0.769  1.0
  Y  Y5  1  0.428  0.718  0.605  1.0
  Y  Y6  1  0.002  0.726  0.731  1.0
  Y  Y7  1  0.572  0.218  0.895  1.0
  Be  Be8  1  0.416  0.859  0.886  1.0
  Be  Be9  1  0.584  0.359  0.614  1.0
  Be  Be10  1  0.084  0.141  0.386  1.0
  Be  Be11  1  0.916  0.641  0.114  1.0
  Al  Al12  1  0.765  0.921  0.013  1.0
  Al  Al13  1  0.735  0.079  0.513  1.0
  Al  Al14  1  0.235  0.421  0.487  1.0
  Al  Al15  1  0.265  0.579  0.987  1.0
  B  B16  1  0.825  0.530  0.940  1.0
  B  B17  1  0.175  0.030  0.560  1.0
  B  B18  1  0.675  0.470  0.440  1.0
  B  B19  1  0.325  0.970  0.060  1.0
  O  O20  1  0.724  0.543  0.323  1.0
  O  O21  1  0.415  0.406  0.049  1.0
  O  O22  1  0.801  0.801  0.172  1.0
  O  O23  1  0.620  0.088  0.097  1.0
  O  O24  1  0.116  0.588  0.137  1.0
  O  O25  1  0.309  0.047  0.936  1.0
  O  O26  1  0.892  0.709  0.945  1.0
  O  O27  1  0.108  0.209  0.555  1.0
  O  O28  1  0.691  0.547  0.564  1.0
  O  O29  1  0.884  0.088  0.363  1.0
  O  O30  1  0.380  0.588  0.403  1.0
  O  O31  1  0.199  0.301  0.328  1.0
  O  O32  1  0.585  0.906  0.451  1.0
  O  O33  1  0.276  0.043  0.177  1.0
  O  O34  1  0.776  0.457  0.823  1.0
  O  O35  1  0.384  0.412  0.637  1.0
  O  O36  1  0.880  0.912  0.597  1.0
  O  O37  1  0.699  0.199  0.672  1.0
  O  O38  1  0.085  0.594  0.549  1.0
  O  O39  1  0.608  0.291  0.445  1.0
  O  O40  1  0.191  0.953  0.436  1.0
  O  O41  1  0.392  0.791  0.055  1.0
  O  O42  1  0.809  0.453  0.064  1.0
  O  O43  1  0.915  0.094  0.951  1.0
  O  O44  1  0.301  0.699  0.828  1.0
  O  O45  1  0.120  0.412  0.903  1.0
  O  O46  1  0.616  0.912  0.863  1.0
  O  O47  1  0.224  0.957  0.677  1.0
[/CIF]
.