The crystal structure described by MgNiSi2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. Mg(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(3) atoms. Ni(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ni(1)O6 octahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-60°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ni(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2NiO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.283
_cell_length_b   6.644
_cell_length_c   6.644
_cell_angle_alpha   85.323
_cell_angle_beta   76.295
_cell_angle_gamma   76.290
_symmetry_Int_Tables_number   1
_cell_volume   220.007
_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  0.750  0.246  0.754  1.0
  Mg  Mg1  1  0.250  0.754  0.246  1.0
  Ni  Ni2  1  0.250  0.098  0.902  1.0
  Ni  Ni3  1  0.750  0.902  0.098  1.0
  O  O4  1  0.495  0.322  0.385  1.0
  O  O5  1  0.005  0.615  0.678  1.0
  O  O6  1  0.505  0.678  0.615  1.0
  O  O7  1  0.995  0.385  0.322  1.0
  O  O8  1  0.133  0.132  0.621  1.0
  O  O9  1  0.367  0.379  0.868  1.0
  O  O10  1  0.867  0.868  0.379  1.0
  O  O11  1  0.633  0.621  0.132  1.0
  O  O12  1  0.852  0.210  0.031  1.0
  O  O13  1  0.648  0.969  0.790  1.0
  O  O14  1  0.352  0.031  0.210  1.0
  O  O15  1  0.148  0.790  0.969  1.0
  Si  Si16  1  0.247  0.209  0.387  1.0
  Si  Si17  1  0.253  0.613  0.791  1.0
  Si  Si18  1  0.747  0.387  0.209  1.0
  Si  Si19  1  0.753  0.791  0.613  1.0
[/CIF]
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The crystal structure described by MgNiSi2O6 is Esseneite structured and crystallizes in the monoclinic C2/c space group. Mg(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(3) atoms. Ni(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with two equivalent Ni(1)O6 octahedra. Si(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form SiO4 tetrahedra that share corners with three equivalent Ni(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 43-60°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to one Mg(1), one Ni(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), two equivalent Ni(1), and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_MgSi2NiO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.283
_cell_length_b   6.644
_cell_length_c   6.644
_cell_angle_alpha   85.323
_cell_angle_beta   76.295
_cell_angle_gamma   76.290
_symmetry_Int_Tables_number   1
_cell_volume   220.007
_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  0.750  0.246  0.754  1.0
  Mg  Mg1  1  0.250  0.754  0.246  1.0
  Ni  Ni2  1  0.250  0.098  0.902  1.0
  Ni  Ni3  1  0.750  0.902  0.098  1.0
  O  O4  1  0.495  0.322  0.385  1.0
  O  O5  1  0.005  0.615  0.678  1.0
  O  O6  1  0.505  0.678  0.615  1.0
  O  O7  1  0.995  0.385  0.322  1.0
  O  O8  1  0.133  0.132  0.621  1.0
  O  O9  1  0.367  0.379  0.868  1.0
  O  O10  1  0.867  0.868  0.379  1.0
  O  O11  1  0.633  0.621  0.132  1.0
  O  O12  1  0.852  0.210  0.031  1.0
  O  O13  1  0.648  0.969  0.790  1.0
  O  O14  1  0.352  0.031  0.210  1.0
  O  O15  1  0.148  0.790  0.969  1.0
  Si  Si16  1  0.247  0.209  0.387  1.0
  Si  Si17  1  0.253  0.613  0.791  1.0
  Si  Si18  1  0.747  0.387  0.209  1.0
  Si  Si19  1  0.753  0.791  0.613  1.0
[/CIF]
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