The structure described by BaAl4O7 crystallizes in the orthorhombic Pmc2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(7), and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to two equivalent O(2), four equivalent O(5), and four equivalent O(6) atoms. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(4), one O(6), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the third Al site, Al(3) is bonded to one O(2), one O(5), one O(6), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form corner-sharing AlO4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(2), one Al(2), and one Al(3) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(2), one Al(1), and one Al(3) atom. In the third O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Al(2), and one Al(4) atom. In the fourth O site, O(8) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the fifth O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1) and two equivalent Al(4) atoms. In the sixth O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(2) and two equivalent Al(3) atoms. In the seventh O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one Al(1), and one Al(4) atom. In the eighth O site, O(4) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(4) atom. is represented by the CIF file [CIF]
data_BaAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.961
_cell_length_b   10.361
_cell_length_c   13.047
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   670.630
_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
  Ba  Ba0  1  0.027  0.260  0.000  1.0
  Ba  Ba1  1  0.973  0.760  0.000  1.0
  Ba  Ba2  1  0.483  0.585  0.500  1.0
  Ba  Ba3  1  0.517  0.085  0.500  1.0
  Al  Al4  1  0.952  0.074  0.749  1.0
  Al  Al5  1  0.952  0.074  0.251  1.0
  Al  Al6  1  0.048  0.574  0.251  1.0
  Al  Al7  1  0.048  0.574  0.749  1.0
  Al  Al8  1  0.449  0.261  0.751  1.0
  Al  Al9  1  0.449  0.261  0.249  1.0
  Al  Al10  1  0.551  0.761  0.249  1.0
  Al  Al11  1  0.551  0.761  0.751  1.0
  Al  Al12  1  0.953  0.325  0.618  1.0
  Al  Al13  1  0.953  0.325  0.382  1.0
  Al  Al14  1  0.047  0.825  0.382  1.0
  Al  Al15  1  0.047  0.825  0.618  1.0
  Al  Al16  1  0.459  0.011  0.882  1.0
  Al  Al17  1  0.459  0.011  0.118  1.0
  Al  Al18  1  0.541  0.511  0.118  1.0
  Al  Al19  1  0.541  0.511  0.882  1.0
  O  O20  1  0.543  0.078  0.000  1.0
  O  O21  1  0.457  0.578  0.000  1.0
  O  O22  1  0.038  0.256  0.500  1.0
  O  O23  1  0.962  0.756  0.500  1.0
  O  O24  1  0.108  0.025  0.862  1.0
  O  O25  1  0.108  0.025  0.138  1.0
  O  O26  1  0.892  0.525  0.138  1.0
  O  O27  1  0.892  0.525  0.862  1.0
  O  O28  1  0.609  0.109  0.782  1.0
  O  O29  1  0.609  0.109  0.218  1.0
  O  O30  1  0.391  0.609  0.218  1.0
  O  O31  1  0.391  0.609  0.782  1.0
  O  O32  1  0.603  0.306  0.636  1.0
  O  O33  1  0.603  0.306  0.364  1.0
  O  O34  1  0.397  0.806  0.364  1.0
  O  O35  1  0.397  0.806  0.636  1.0
  O  O36  1  0.952  0.986  0.634  1.0
  O  O37  1  0.952  0.986  0.366  1.0
  O  O38  1  0.048  0.486  0.366  1.0
  O  O39  1  0.048  0.486  0.634  1.0
  O  O40  1  0.439  0.350  0.865  1.0
  O  O41  1  0.439  0.350  0.135  1.0
  O  O42  1  0.561  0.850  0.135  1.0
  O  O43  1  0.561  0.850  0.865  1.0
  O  O44  1  0.105  0.227  0.718  1.0
  O  O45  1  0.105  0.227  0.282  1.0
  O  O46  1  0.895  0.727  0.282  1.0
  O  O47  1  0.895  0.727  0.718  1.0
[/CIF]
.
The structure described by BaAl4O7 crystallizes in the orthorhombic Pmc2_1 space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(7), and four equivalent O(3) atoms. In the second Ba site, Ba(2) is bonded in a 10-coordinate geometry to two equivalent O(2), four equivalent O(5), and four equivalent O(6) atoms. There are four inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(3), one O(4), one O(6), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the second Al site, Al(2) is bonded to one O(4), one O(5), one O(7), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the third Al site, Al(3) is bonded to one O(2), one O(5), one O(6), and one O(8) atom to form corner-sharing AlO4 tetrahedra. In the fourth Al site, Al(4) is bonded to one O(1), one O(3), one O(4), and one O(7) atom to form corner-sharing AlO4 tetrahedra. There are eight inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(2), one Al(2), and one Al(3) atom. In the second O site, O(6) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(2), one Al(1), and one Al(3) atom. In the third O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Al(2), and one Al(4) atom. In the fourth O site, O(8) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(3) atom. In the fifth O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1) and two equivalent Al(4) atoms. In the sixth O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(2) and two equivalent Al(3) atoms. In the seventh O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Ba(1), one Al(1), and one Al(4) atom. In the eighth O site, O(4) is bonded in a trigonal planar geometry to one Al(1), one Al(2), and one Al(4) atom. is represented by the CIF file [CIF]
data_BaAl4O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.961
_cell_length_b   10.361
_cell_length_c   13.047
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   670.630
_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
  Ba  Ba0  1  0.027  0.260  0.000  1.0
  Ba  Ba1  1  0.973  0.760  0.000  1.0
  Ba  Ba2  1  0.483  0.585  0.500  1.0
  Ba  Ba3  1  0.517  0.085  0.500  1.0
  Al  Al4  1  0.952  0.074  0.749  1.0
  Al  Al5  1  0.952  0.074  0.251  1.0
  Al  Al6  1  0.048  0.574  0.251  1.0
  Al  Al7  1  0.048  0.574  0.749  1.0
  Al  Al8  1  0.449  0.261  0.751  1.0
  Al  Al9  1  0.449  0.261  0.249  1.0
  Al  Al10  1  0.551  0.761  0.249  1.0
  Al  Al11  1  0.551  0.761  0.751  1.0
  Al  Al12  1  0.953  0.325  0.618  1.0
  Al  Al13  1  0.953  0.325  0.382  1.0
  Al  Al14  1  0.047  0.825  0.382  1.0
  Al  Al15  1  0.047  0.825  0.618  1.0
  Al  Al16  1  0.459  0.011  0.882  1.0
  Al  Al17  1  0.459  0.011  0.118  1.0
  Al  Al18  1  0.541  0.511  0.118  1.0
  Al  Al19  1  0.541  0.511  0.882  1.0
  O  O20  1  0.543  0.078  0.000  1.0
  O  O21  1  0.457  0.578  0.000  1.0
  O  O22  1  0.038  0.256  0.500  1.0
  O  O23  1  0.962  0.756  0.500  1.0
  O  O24  1  0.108  0.025  0.862  1.0
  O  O25  1  0.108  0.025  0.138  1.0
  O  O26  1  0.892  0.525  0.138  1.0
  O  O27  1  0.892  0.525  0.862  1.0
  O  O28  1  0.609  0.109  0.782  1.0
  O  O29  1  0.609  0.109  0.218  1.0
  O  O30  1  0.391  0.609  0.218  1.0
  O  O31  1  0.391  0.609  0.782  1.0
  O  O32  1  0.603  0.306  0.636  1.0
  O  O33  1  0.603  0.306  0.364  1.0
  O  O34  1  0.397  0.806  0.364  1.0
  O  O35  1  0.397  0.806  0.636  1.0
  O  O36  1  0.952  0.986  0.634  1.0
  O  O37  1  0.952  0.986  0.366  1.0
  O  O38  1  0.048  0.486  0.366  1.0
  O  O39  1  0.048  0.486  0.634  1.0
  O  O40  1  0.439  0.350  0.865  1.0
  O  O41  1  0.439  0.350  0.135  1.0
  O  O42  1  0.561  0.850  0.135  1.0
  O  O43  1  0.561  0.850  0.865  1.0
  O  O44  1  0.105  0.227  0.718  1.0
  O  O45  1  0.105  0.227  0.282  1.0
  O  O46  1  0.895  0.727  0.282  1.0
  O  O47  1  0.895  0.727  0.718  1.0
[/CIF]
.