The compound described by MgTa2(FeO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O4 tetrahedra, and  an edgeedge with one Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-77°. 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(5), one O(6), and one O(7) atom to form distorted TaO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ta(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-26°. In the second Ta site, Ta(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ta(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form distorted FeO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-70°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted FeO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-26°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ta(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ta(1), one Ta(2), and one Fe(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ta(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Ta(1), one Ta(2), one Fe(1), and one Fe(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ta(1), one Ta(2), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mg(1), one Ta(1), and one Fe(2) atom. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ta(1), one Ta(2), and one Fe(2) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Mg(1), one Ta(2), and one Fe(1) atom. is represented by the CIF file [CIF]
data_MgTa2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.155
_cell_length_b   5.184
_cell_length_c   6.451
_cell_angle_alpha   88.873
_cell_angle_beta   90.482
_cell_angle_gamma   103.076
_symmetry_Int_Tables_number   1
_cell_volume   167.879
_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  0.641  0.432  0.360  1.0
  Ta  Ta1  1  0.003  0.733  0.824  1.0
  Ta  Ta2  1  0.023  0.231  0.127  1.0
  Fe  Fe3  1  0.373  0.845  0.359  1.0
  Fe  Fe4  1  0.513  0.233  0.832  1.0
  O  O5  1  0.268  0.933  0.643  1.0
  O  O6  1  0.217  0.457  0.887  1.0
  O  O7  1  0.267  0.446  0.322  1.0
  O  O8  1  0.236  0.966  0.080  1.0
  O  O9  1  0.806  0.011  0.889  1.0
  O  O10  1  0.752  0.541  0.638  1.0
  O  O11  1  0.796  0.502  0.074  1.0
  O  O12  1  0.743  0.082  0.324  1.0
[/CIF]
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The compound described by MgTa2(FeO4)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(3), one O(6), one O(7), and one O(8) atom to form distorted MgO4 tetrahedra that share  a cornercorner with one Ta(2)O6 octahedra, corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Fe(1)O4 tetrahedra, and  an edgeedge with one Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-77°. 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(5), one O(6), and one O(7) atom to form distorted TaO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ta(2)O6 octahedra, and edges with two equivalent Fe(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-26°. In the second Ta site, Ta(2) is bonded to one O(2), one O(3), one O(4), one O(5), one O(7), and one O(8) atom to form TaO6 octahedra that share  a cornercorner with one Mg(1)O4 tetrahedra, corners with three equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ta(1)O6 octahedra, edges with two equivalent Fe(2)O6 octahedra, and  an edgeedge with one Mg(1)O4 tetrahedra. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(1), one O(3), one O(4), and one O(8) atom to form distorted FeO4 tetrahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Ta(2)O6 octahedra, and corners with two equivalent Mg(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 35-70°. In the second Fe site, Fe(2) is bonded to one O(1), one O(2), one O(4), one O(5), one O(6), and one O(7) atom to form distorted FeO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Mg(1)O4 tetrahedra, corners with two equivalent Fe(1)O4 tetrahedra, edges with two equivalent Ta(1)O6 octahedra, and edges with two equivalent Ta(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-26°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ta(1), one Fe(1), and one Fe(2) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ta(1), one Ta(2), and one Fe(2) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ta(2), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a rectangular see-saw-like geometry to one Ta(1), one Ta(2), one Fe(1), and one Fe(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ta(1), one Ta(2), and one Fe(2) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Mg(1), one Ta(1), and one Fe(2) atom. In the seventh O site, O(7) is bonded in a rectangular see-saw-like geometry to one Mg(1), one Ta(1), one Ta(2), and one Fe(2) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Mg(1), one Ta(2), and one Fe(1) atom. is represented by the CIF file [CIF]
data_MgTa2(FeO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.155
_cell_length_b   5.184
_cell_length_c   6.451
_cell_angle_alpha   88.873
_cell_angle_beta   90.482
_cell_angle_gamma   103.076
_symmetry_Int_Tables_number   1
_cell_volume   167.879
_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  0.641  0.432  0.360  1.0
  Ta  Ta1  1  0.003  0.733  0.824  1.0
  Ta  Ta2  1  0.023  0.231  0.127  1.0
  Fe  Fe3  1  0.373  0.845  0.359  1.0
  Fe  Fe4  1  0.513  0.233  0.832  1.0
  O  O5  1  0.268  0.933  0.643  1.0
  O  O6  1  0.217  0.457  0.887  1.0
  O  O7  1  0.267  0.446  0.322  1.0
  O  O8  1  0.236  0.966  0.080  1.0
  O  O9  1  0.806  0.011  0.889  1.0
  O  O10  1  0.752  0.541  0.638  1.0
  O  O11  1  0.796  0.502  0.074  1.0
  O  O12  1  0.743  0.082  0.324  1.0
[/CIF]
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