The crystal structure described by MgTb4Al2(FeO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(12), one O(3), one O(4), and one O(9) atom to form MgO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid, and corners with two equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°. There are four inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. In the second Tb site, Tb(2) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. In the third Tb site, Tb(3) is bonded in a 7-coordinate geometry to one O(10), one O(3), one O(4), one O(6), one O(7), one O(8), and one O(9) atom. In the fourth Tb site, Tb(4) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(3), one O(4), one O(5), one O(7), one O(8), and one O(9) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(12), one O(2), one O(5), and one O(8) atom to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Al(2)O5 trigonal bipyramid, and  an edgeedge with one Al(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 55°. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(10), one O(11), one O(3), one O(6), and one O(7) atom. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(11), one O(2), one O(4), one O(6), and one O(7) atom to form distorted AlO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra and  a cornercorner with one Fe(1)O5 trigonal bipyramid. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(5), one O(8), and one O(9) atom to form AlO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid, and  an edgeedge with one Fe(1)O5 trigonal bipyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Tb(1), one Tb(2), one Fe(1), and one Al(2) atom to form distorted OTb2AlFe trigonal pyramids that share  a cornercorner with one O(10)Tb3AlFe square pyramid, corners with three equivalent O(12)Tb2MgFe trigonal pyramids, and  an edgeedge with one O(8)Tb2AlFe trigonal pyramid. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Tb(1), one Tb(2), one Fe(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(3), one Tb(4), one Fe(2), and one Al(2) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tb(3), one Tb(4), and one Al(1) atom to form distorted OTb2MgAl tetrahedra that share  a cornercorner with one O(10)Tb3AlFe square pyramid,  a cornercorner with one O(12)Tb2MgFe trigonal pyramid, corners with two equivalent O(8)Tb2AlFe trigonal pyramids, and  an edgeedge with one O(10)Tb3AlFe square pyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Tb(1), one Tb(2), one Tb(4), one Fe(1), and one Al(2) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Tb(1), one Tb(2), one Tb(3), one Fe(2), and one Al(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Tb(3), one Tb(4), one Fe(2), and one Al(1) atom. In the eighth O site, O(8) is bonded to one Tb(3), one Tb(4), one Fe(1), and one Al(2) atom to form distorted OTb2AlFe trigonal pyramids that share corners with two equivalent O(4)Tb2MgAl tetrahedra,  a cornercorner with one O(12)Tb2MgFe trigonal pyramid,  an edgeedge with one O(10)Tb3AlFe square pyramid, and  an edgeedge with one O(1)Tb2AlFe trigonal pyramid. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(3), one Tb(4), and one Al(2) atom. In the tenth O site, O(10) is bonded to one Tb(1), one Tb(3), one Tb(4), one Fe(2), and one Al(1) atom to form distorted OTb3AlFe square pyramids that share  a cornercorner with one O(4)Tb2MgAl tetrahedra,  a cornercorner with one O(1)Tb2AlFe trigonal pyramid,  a cornercorner with one O(12)Tb2MgFe trigonal pyramid,  an edgeedge with one O(4)Tb2MgAl tetrahedra, and  an edgeedge with one O(8)Tb2AlFe trigonal pyramid. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Tb(1), one Tb(2), one Tb(4), one Fe(2), and one Al(1) atom. In the twelfth O site, O(12) is bonded to one Mg(1), one Tb(1), one Tb(2), and one Fe(1) atom to form OTb2MgFe trigonal pyramids that share  a cornercorner with one O(10)Tb3AlFe square pyramid,  a cornercorner with one O(4)Tb2MgAl tetrahedra,  a cornercorner with one O(8)Tb2AlFe trigonal pyramid, and corners with three equivalent O(1)Tb2AlFe trigonal pyramids. is represented by the CIF card [CIF]
data_Tb4MgAl2(FeO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.364
_cell_length_b   5.856
_cell_length_c   8.278
_cell_angle_alpha   87.219
_cell_angle_beta   85.057
_cell_angle_gamma   90.388
_symmetry_Int_Tables_number   1
_cell_volume   258.734
_cell_formula_units_Z   1
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
  Tb  Tb0  1  0.537  0.585  0.278  1.0
  Tb  Tb1  1  0.958  0.089  0.246  1.0
  Tb  Tb2  1  0.448  0.408  0.718  1.0
  Tb  Tb3  1  0.028  0.870  0.728  1.0
  Mg  Mg4  1  0.894  0.287  0.892  1.0
  Al  Al5  1  0.006  0.455  0.502  1.0
  Al  Al6  1  0.466  0.941  0.970  1.0
  Fe  Fe7  1  0.048  0.627  0.095  1.0
  Fe  Fe8  1  0.495  0.001  0.497  1.0
  O  O9  1  0.311  0.898  0.182  1.0
  O  O10  1  0.147  0.435  0.287  1.0
  O  O11  1  0.668  0.068  0.788  1.0
  O  O12  1  0.863  0.517  0.715  1.0
  O  O13  1  0.773  0.854  0.060  1.0
  O  O14  1  0.705  0.317  0.456  1.0
  O  O15  1  0.185  0.181  0.564  1.0
  O  O16  1  0.311  0.688  0.891  1.0
  O  O17  1  0.218  0.149  0.905  1.0
  O  O18  1  0.275  0.664  0.539  1.0
  O  O19  1  0.784  0.813  0.425  1.0
  O  O20  1  0.756  0.366  0.101  1.0
[/CIF]
.
The crystal structure described by MgTb4Al2(FeO6)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(12), one O(3), one O(4), and one O(9) atom to form MgO4 tetrahedra that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid, and corners with two equivalent Al(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°. There are four inequivalent Tb sites. In the first Tb site, Tb(1) is bonded in a 7-coordinate geometry to one O(1), one O(10), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. In the second Tb site, Tb(2) is bonded in a 6-coordinate geometry to one O(1), one O(11), one O(12), one O(2), one O(5), and one O(6) atom. In the third Tb site, Tb(3) is bonded in a 7-coordinate geometry to one O(10), one O(3), one O(4), one O(6), one O(7), one O(8), and one O(9) atom. In the fourth Tb site, Tb(4) is bonded in a 8-coordinate geometry to one O(10), one O(11), one O(3), one O(4), one O(5), one O(7), one O(8), and one O(9) atom. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(12), one O(2), one O(5), and one O(8) atom to form distorted FeO5 trigonal bipyramids that share  a cornercorner with one Al(1)O6 octahedra,  a cornercorner with one Mg(1)O4 tetrahedra,  a cornercorner with one Al(2)O5 trigonal bipyramid, and  an edgeedge with one Al(2)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 55°. In the second Fe site, Fe(2) is bonded in a 5-coordinate geometry to one O(10), one O(11), one O(3), one O(6), and one O(7) atom. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to one O(10), one O(11), one O(2), one O(4), one O(6), and one O(7) atom to form distorted AlO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra and  a cornercorner with one Fe(1)O5 trigonal bipyramid. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(5), one O(8), and one O(9) atom to form AlO5 trigonal bipyramids that share corners with two equivalent Mg(1)O4 tetrahedra,  a cornercorner with one Fe(1)O5 trigonal bipyramid, and  an edgeedge with one Fe(1)O5 trigonal bipyramid. There are twelve inequivalent O sites. In the first O site, O(1) is bonded to one Tb(1), one Tb(2), one Fe(1), and one Al(2) atom to form distorted OTb2AlFe trigonal pyramids that share  a cornercorner with one O(10)Tb3AlFe square pyramid, corners with three equivalent O(12)Tb2MgFe trigonal pyramids, and  an edgeedge with one O(8)Tb2AlFe trigonal pyramid. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Tb(1), one Tb(2), one Fe(1), and one Al(1) atom. In the third O site, O(3) is bonded in a 5-coordinate geometry to one Mg(1), one Tb(3), one Tb(4), one Fe(2), and one Al(2) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Tb(3), one Tb(4), and one Al(1) atom to form distorted OTb2MgAl tetrahedra that share  a cornercorner with one O(10)Tb3AlFe square pyramid,  a cornercorner with one O(12)Tb2MgFe trigonal pyramid, corners with two equivalent O(8)Tb2AlFe trigonal pyramids, and  an edgeedge with one O(10)Tb3AlFe square pyramid. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Tb(1), one Tb(2), one Tb(4), one Fe(1), and one Al(2) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Tb(1), one Tb(2), one Tb(3), one Fe(2), and one Al(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Tb(3), one Tb(4), one Fe(2), and one Al(1) atom. In the eighth O site, O(8) is bonded to one Tb(3), one Tb(4), one Fe(1), and one Al(2) atom to form distorted OTb2AlFe trigonal pyramids that share corners with two equivalent O(4)Tb2MgAl tetrahedra,  a cornercorner with one O(12)Tb2MgFe trigonal pyramid,  an edgeedge with one O(10)Tb3AlFe square pyramid, and  an edgeedge with one O(1)Tb2AlFe trigonal pyramid. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Mg(1), one Tb(3), one Tb(4), and one Al(2) atom. In the tenth O site, O(10) is bonded to one Tb(1), one Tb(3), one Tb(4), one Fe(2), and one Al(1) atom to form distorted OTb3AlFe square pyramids that share  a cornercorner with one O(4)Tb2MgAl tetrahedra,  a cornercorner with one O(1)Tb2AlFe trigonal pyramid,  a cornercorner with one O(12)Tb2MgFe trigonal pyramid,  an edgeedge with one O(4)Tb2MgAl tetrahedra, and  an edgeedge with one O(8)Tb2AlFe trigonal pyramid. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Tb(1), one Tb(2), one Tb(4), one Fe(2), and one Al(1) atom. In the twelfth O site, O(12) is bonded to one Mg(1), one Tb(1), one Tb(2), and one Fe(1) atom to form OTb2MgFe trigonal pyramids that share  a cornercorner with one O(10)Tb3AlFe square pyramid,  a cornercorner with one O(4)Tb2MgAl tetrahedra,  a cornercorner with one O(8)Tb2AlFe trigonal pyramid, and corners with three equivalent O(1)Tb2AlFe trigonal pyramids. is represented by the CIF card [CIF]
data_Tb4MgAl2(FeO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.364
_cell_length_b   5.856
_cell_length_c   8.278
_cell_angle_alpha   87.219
_cell_angle_beta   85.057
_cell_angle_gamma   90.388
_symmetry_Int_Tables_number   1
_cell_volume   258.734
_cell_formula_units_Z   1
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
  Tb  Tb0  1  0.537  0.585  0.278  1.0
  Tb  Tb1  1  0.958  0.089  0.246  1.0
  Tb  Tb2  1  0.448  0.408  0.718  1.0
  Tb  Tb3  1  0.028  0.870  0.728  1.0
  Mg  Mg4  1  0.894  0.287  0.892  1.0
  Al  Al5  1  0.006  0.455  0.502  1.0
  Al  Al6  1  0.466  0.941  0.970  1.0
  Fe  Fe7  1  0.048  0.627  0.095  1.0
  Fe  Fe8  1  0.495  0.001  0.497  1.0
  O  O9  1  0.311  0.898  0.182  1.0
  O  O10  1  0.147  0.435  0.287  1.0
  O  O11  1  0.668  0.068  0.788  1.0
  O  O12  1  0.863  0.517  0.715  1.0
  O  O13  1  0.773  0.854  0.060  1.0
  O  O14  1  0.705  0.317  0.456  1.0
  O  O15  1  0.185  0.181  0.564  1.0
  O  O16  1  0.311  0.688  0.891  1.0
  O  O17  1  0.218  0.149  0.905  1.0
  O  O18  1  0.275  0.664  0.539  1.0
  O  O19  1  0.784  0.813  0.425  1.0
  O  O20  1  0.756  0.366  0.101  1.0
[/CIF]
.