The material structure described by Mg2Ta2CrO8 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(11), one O(12), one O(14), one O(15), one O(16), and one O(9) atom. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(15), and one O(16) atom. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(13), one O(14), one O(16), and one O(9) atom. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(13), one O(14), one O(15), and one O(9) atom. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(11), one O(16), one O(4), one O(5), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Ta(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. In the second Ta site, Ta(2) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(15), one O(2), one O(3), and one O(6) atom. In the third Ta site, Ta(3) is bonded to one O(10), one O(12), one O(14), one O(2), one O(3), and one O(7) atom to form distorted TaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra and corners with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-55°. In the fourth Ta site, Ta(4) is bonded to one O(1), one O(11), one O(13), one O(4), one O(8), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form CrO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. In the second Cr site, Cr(2) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form CrO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ta(1), one Ta(4), and one Cr(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ta(2), one Ta(3), and one Cr(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ta(2), one Ta(3), and one Cr(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ta(1), one Ta(4), and one Cr(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ta(1), one Cr(1), and one Cr(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ta(2), one Cr(1), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ta(3), one Cr(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ta(4), one Cr(1), and one Cr(2) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Ta(1), and one Ta(4) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Ta(2), and one Ta(3) atom. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Ta(1), and one Ta(4) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Ta(2), and one Ta(3) atom. In the thirteenth O site, O(13) is bonded to one Mg(2), one Mg(3), one Mg(4), and one Ta(4) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. In the fourteenth O site, O(14) is bonded to one Mg(1), one Mg(3), one Mg(4), and one Ta(3) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. In the fifteenth O site, O(15) is bonded to one Mg(1), one Mg(2), one Mg(4), and one Ta(2) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. In the sixteenth O site, O(16) is bonded to one Mg(1), one Mg(2), one Mg(3), and one Ta(1) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. is represented by the CIF file [CIF]
data_Mg2Ta2CrO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.219
_cell_length_b   6.056
_cell_length_c   10.151
_cell_angle_alpha   106.941
_cell_angle_beta   91.476
_cell_angle_gamma   90.198
_symmetry_Int_Tables_number   1
_cell_volume   306.833
_cell_formula_units_Z   2
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  0.756  0.418  0.546  1.0
  Mg  Mg1  1  0.744  0.871  0.453  1.0
  Mg  Mg2  1  0.244  0.583  0.452  1.0
  Mg  Mg3  1  0.257  0.130  0.545  1.0
  Ta  Ta4  1  0.737  0.280  0.236  1.0
  Ta  Ta5  1  0.765  0.042  0.762  1.0
  Ta  Ta6  1  0.264  0.720  0.762  1.0
  Ta  Ta7  1  0.236  0.960  0.236  1.0
  Cr  Cr8  1  0.248  0.350  1.000  1.0
  Cr  Cr9  1  0.748  0.652  0.999  1.0
  O  O10  1  0.066  0.189  0.148  1.0
  O  O11  1  0.436  0.031  0.849  1.0
  O  O12  1  0.935  0.814  0.850  1.0
  O  O13  1  0.565  0.966  0.149  1.0
  O  O14  1  0.579  0.425  0.118  1.0
  O  O15  1  0.918  0.305  0.880  1.0
  O  O16  1  0.415  0.573  0.881  1.0
  O  O17  1  0.076  0.701  0.119  1.0
  O  O18  1  0.449  0.291  0.374  1.0
  O  O19  1  0.051  0.917  0.625  1.0
  O  O20  1  0.949  0.085  0.373  1.0
  O  O21  1  0.550  0.709  0.624  1.0
  O  O22  1  0.374  0.840  0.383  1.0
  O  O23  1  0.126  0.454  0.614  1.0
  O  O24  1  0.626  0.161  0.614  1.0
  O  O25  1  0.874  0.547  0.383  1.0
[/CIF]
.
The material structure described by Mg2Ta2CrO8 crystallizes in the triclinic P1 space group. There are four inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a 6-coordinate geometry to one O(11), one O(12), one O(14), one O(15), one O(16), and one O(9) atom. In the second Mg site, Mg(2) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(15), and one O(16) atom. In the third Mg site, Mg(3) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(13), one O(14), one O(16), and one O(9) atom. In the fourth Mg site, Mg(4) is bonded in a 6-coordinate geometry to one O(10), one O(11), one O(13), one O(14), one O(15), and one O(9) atom. There are four inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(1), one O(11), one O(16), one O(4), one O(5), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Ta(4)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. In the second Ta site, Ta(2) is bonded in a 6-coordinate geometry to one O(10), one O(12), one O(15), one O(2), one O(3), and one O(6) atom. In the third Ta site, Ta(3) is bonded to one O(10), one O(12), one O(14), one O(2), one O(3), and one O(7) atom to form distorted TaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra and corners with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-55°. In the fourth Ta site, Ta(4) is bonded to one O(1), one O(11), one O(13), one O(4), one O(8), and one O(9) atom to form distorted TaO6 octahedra that share corners with two equivalent Cr(1)O6 octahedra, corners with two equivalent Cr(2)O6 octahedra, and edges with two equivalent Ta(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form CrO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent Cr(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-55°. In the second Cr site, Cr(2) is bonded to one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form CrO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with two equivalent Ta(3)O6 octahedra, corners with two equivalent Ta(4)O6 octahedra, and edges with two equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 47-56°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a trigonal planar geometry to one Ta(1), one Ta(4), and one Cr(1) atom. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ta(2), one Ta(3), and one Cr(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ta(2), one Ta(3), and one Cr(2) atom. In the fourth O site, O(4) is bonded in a trigonal planar geometry to one Ta(1), one Ta(4), and one Cr(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Ta(1), one Cr(1), and one Cr(2) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Ta(2), one Cr(1), and one Cr(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Ta(3), one Cr(1), and one Cr(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Ta(4), one Cr(1), and one Cr(2) atom. In the ninth O site, O(9) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(3), one Mg(4), one Ta(1), and one Ta(4) atom. In the tenth O site, O(10) is bonded in a 5-coordinate geometry to one Mg(2), one Mg(3), one Mg(4), one Ta(2), and one Ta(3) atom. In the eleventh O site, O(11) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(4), one Ta(1), and one Ta(4) atom. In the twelfth O site, O(12) is bonded in a 5-coordinate geometry to one Mg(1), one Mg(2), one Mg(3), one Ta(2), and one Ta(3) atom. In the thirteenth O site, O(13) is bonded to one Mg(2), one Mg(3), one Mg(4), and one Ta(4) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. In the fourteenth O site, O(14) is bonded to one Mg(1), one Mg(3), one Mg(4), and one Ta(3) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. In the fifteenth O site, O(15) is bonded to one Mg(1), one Mg(2), one Mg(4), and one Ta(2) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. In the sixteenth O site, O(16) is bonded to one Mg(1), one Mg(2), one Mg(3), and one Ta(1) atom to form a mixture of corner and edge-sharing OMg3Ta trigonal pyramids. is represented by the CIF file [CIF]
data_Mg2Ta2CrO8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.219
_cell_length_b   6.056
_cell_length_c   10.151
_cell_angle_alpha   106.941
_cell_angle_beta   91.476
_cell_angle_gamma   90.198
_symmetry_Int_Tables_number   1
_cell_volume   306.833
_cell_formula_units_Z   2
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  0.756  0.418  0.546  1.0
  Mg  Mg1  1  0.744  0.871  0.453  1.0
  Mg  Mg2  1  0.244  0.583  0.452  1.0
  Mg  Mg3  1  0.257  0.130  0.545  1.0
  Ta  Ta4  1  0.737  0.280  0.236  1.0
  Ta  Ta5  1  0.765  0.042  0.762  1.0
  Ta  Ta6  1  0.264  0.720  0.762  1.0
  Ta  Ta7  1  0.236  0.960  0.236  1.0
  Cr  Cr8  1  0.248  0.350  1.000  1.0
  Cr  Cr9  1  0.748  0.652  0.999  1.0
  O  O10  1  0.066  0.189  0.148  1.0
  O  O11  1  0.436  0.031  0.849  1.0
  O  O12  1  0.935  0.814  0.850  1.0
  O  O13  1  0.565  0.966  0.149  1.0
  O  O14  1  0.579  0.425  0.118  1.0
  O  O15  1  0.918  0.305  0.880  1.0
  O  O16  1  0.415  0.573  0.881  1.0
  O  O17  1  0.076  0.701  0.119  1.0
  O  O18  1  0.449  0.291  0.374  1.0
  O  O19  1  0.051  0.917  0.625  1.0
  O  O20  1  0.949  0.085  0.373  1.0
  O  O21  1  0.550  0.709  0.624  1.0
  O  O22  1  0.374  0.840  0.383  1.0
  O  O23  1  0.126  0.454  0.614  1.0
  O  O24  1  0.626  0.161  0.614  1.0
  O  O25  1  0.874  0.547  0.383  1.0
[/CIF]
.