The crystal structure described by MgTa2(FeO4)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(7) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Ta(1)O6 octahedra, edges with two equivalent Ta(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(2), one O(4), one O(8), and two equivalent O(6) atoms to form distorted TaO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 17-25°. In the second Ta site, Ta(2) is bonded to one O(1), one O(5), one O(7), one O(8), and two equivalent O(3) atoms to form TaO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-17°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms. In the second Fe site, Fe(2) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-36°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ta(1), one Ta(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Ta(1), and one Fe(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ta(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Ta(1), one Fe(1), and two equivalent Fe(2) atoms to form distorted OMgTaFe3 trigonal pyramids that share corners with two equivalent O(4)MgTaFe3 trigonal pyramids and edges with two equivalent O(5)TaFe3 tetrahedra. In the fifth O site, O(5) is bonded to one Ta(2), one Fe(2), and two equivalent Fe(1) atoms to form OTaFe3 tetrahedra that share corners with two equivalent O(5)TaFe3 tetrahedra and edges with two equivalent O(4)MgTaFe3 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to two equivalent Ta(1) and one Fe(2) atom. In the seventh O site, O(7) is bonded in a distorted square co-planar geometry to two equivalent Mg(1), one Ta(2), and one Fe(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ta(1), one Ta(2), and one Fe(2) atom. is represented by the CIF card [CIF]
data_MgTa2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.857
_cell_length_b   6.857
_cell_length_c   7.171
_cell_angle_alpha   73.172
_cell_angle_beta   106.828
_cell_angle_gamma   146.674
_symmetry_Int_Tables_number   1
_cell_volume   176.553
_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
  Mg  Mg0  1  0.315  0.685  0.483  1.0
  Ta  Ta1  1  0.100  0.900  0.209  1.0
  Ta  Ta2  1  0.903  0.097  0.811  1.0
  Fe  Fe3  1  0.190  0.810  0.791  1.0
  Fe  Fe4  1  0.795  0.205  0.159  1.0
  O  O5  1  0.055  0.945  0.883  1.0
  O  O6  1  0.155  0.845  0.484  1.0
  O  O7  1  0.381  0.619  0.781  1.0
  O  O8  1  0.254  0.746  0.191  1.0
  O  O9  1  0.752  0.248  0.846  1.0
  O  O10  1  0.615  0.385  0.187  1.0
  O  O11  1  0.860  0.140  0.523  1.0
  O  O12  1  0.943  0.057  0.121  1.0
[/CIF]
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The crystal structure described by MgTa2(FeO4)2 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one O(2), one O(3), one O(4), and two equivalent O(7) atoms to form MgO5 trigonal bipyramids that share corners with two equivalent Mg(1)O5 trigonal bipyramids,  an edgeedge with one Ta(1)O6 octahedra, edges with two equivalent Ta(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(2), one O(4), one O(8), and two equivalent O(6) atoms to form distorted TaO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Mg(1)O5 trigonal bipyramid. The corner-sharing octahedral tilt angles range from 17-25°. In the second Ta site, Ta(2) is bonded to one O(1), one O(5), one O(7), one O(8), and two equivalent O(3) atoms to form TaO6 octahedra that share  a cornercorner with one Fe(2)O6 octahedra, corners with two equivalent Ta(2)O6 octahedra,  an edgeedge with one Ta(1)O6 octahedra,  an edgeedge with one Fe(2)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-17°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), and two equivalent O(5) atoms. In the second Fe site, Fe(2) is bonded to one O(5), one O(6), one O(7), one O(8), and two equivalent O(4) atoms to form distorted FeO6 octahedra that share  a cornercorner with one Ta(1)O6 octahedra,  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra,  an edgeedge with one Ta(2)O6 octahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Mg(1)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 3-36°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ta(1), one Ta(2), and one Fe(1) atom. In the second O site, O(2) is bonded in a T-shaped geometry to one Mg(1), one Ta(1), and one Fe(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ta(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded to one Mg(1), one Ta(1), one Fe(1), and two equivalent Fe(2) atoms to form distorted OMgTaFe3 trigonal pyramids that share corners with two equivalent O(4)MgTaFe3 trigonal pyramids and edges with two equivalent O(5)TaFe3 tetrahedra. In the fifth O site, O(5) is bonded to one Ta(2), one Fe(2), and two equivalent Fe(1) atoms to form OTaFe3 tetrahedra that share corners with two equivalent O(5)TaFe3 tetrahedra and edges with two equivalent O(4)MgTaFe3 trigonal pyramids. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to two equivalent Ta(1) and one Fe(2) atom. In the seventh O site, O(7) is bonded in a distorted square co-planar geometry to two equivalent Mg(1), one Ta(2), and one Fe(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ta(1), one Ta(2), and one Fe(2) atom. is represented by the CIF card [CIF]
data_MgTa2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.857
_cell_length_b   6.857
_cell_length_c   7.171
_cell_angle_alpha   73.172
_cell_angle_beta   106.828
_cell_angle_gamma   146.674
_symmetry_Int_Tables_number   1
_cell_volume   176.553
_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
  Mg  Mg0  1  0.315  0.685  0.483  1.0
  Ta  Ta1  1  0.100  0.900  0.209  1.0
  Ta  Ta2  1  0.903  0.097  0.811  1.0
  Fe  Fe3  1  0.190  0.810  0.791  1.0
  Fe  Fe4  1  0.795  0.205  0.159  1.0
  O  O5  1  0.055  0.945  0.883  1.0
  O  O6  1  0.155  0.845  0.484  1.0
  O  O7  1  0.381  0.619  0.781  1.0
  O  O8  1  0.254  0.746  0.191  1.0
  O  O9  1  0.752  0.248  0.846  1.0
  O  O10  1  0.615  0.385  0.187  1.0
  O  O11  1  0.860  0.140  0.523  1.0
  O  O12  1  0.943  0.057  0.121  1.0
[/CIF]
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