The compound described by Mg2Si2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Mg site, Mg(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form MgO12 cuboctahedra that share corners with four equivalent Mg(2)O12 cuboctahedra, faces with four equivalent Mg(2)O12 cuboctahedra, and faces with eight equivalent Si(1)O5 square pyramids. Si(1) is bonded to one O(2) and four equivalent O(1) atoms to form SiO5 square pyramids that share corners with five equivalent Si(1)O5 square pyramids and faces with four equivalent Mg(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Si(1) atoms to form a mixture of distorted corner, face, and edge-sharing OMg4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Mg(2) and two equivalent Si(1) atoms. is represented by the CIF card [CIF]
data_Mg2Si2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.654
_cell_length_b   3.654
_cell_length_c   6.125
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   81.786
_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  0.000  0.000  0.000  1.0
  Mg  Mg1  1  0.000  0.000  0.500  1.0
  Si  Si2  1  0.500  0.500  0.210  1.0
  Si  Si3  1  0.500  0.500  0.790  1.0
  O  O4  1  0.500  0.000  0.223  1.0
  O  O5  1  0.500  0.000  0.777  1.0
  O  O6  1  0.000  0.500  0.223  1.0
  O  O7  1  0.000  0.500  0.777  1.0
  O  O8  1  0.500  0.500  0.500  1.0
[/CIF]
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The compound described by Mg2Si2O5 crystallizes in the tetragonal P4/mmm space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Mg site, Mg(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form MgO12 cuboctahedra that share corners with four equivalent Mg(2)O12 cuboctahedra, faces with four equivalent Mg(2)O12 cuboctahedra, and faces with eight equivalent Si(1)O5 square pyramids. Si(1) is bonded to one O(2) and four equivalent O(1) atoms to form SiO5 square pyramids that share corners with five equivalent Si(1)O5 square pyramids and faces with four equivalent Mg(2)O12 cuboctahedra. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Mg(1), two equivalent Mg(2), and two equivalent Si(1) atoms to form a mixture of distorted corner, face, and edge-sharing OMg4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent Mg(2) and two equivalent Si(1) atoms. is represented by the CIF card [CIF]
data_Mg2Si2O5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.654
_cell_length_b   3.654
_cell_length_c   6.125
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   81.786
_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  0.000  0.000  0.000  1.0
  Mg  Mg1  1  0.000  0.000  0.500  1.0
  Si  Si2  1  0.500  0.500  0.210  1.0
  Si  Si3  1  0.500  0.500  0.790  1.0
  O  O4  1  0.500  0.000  0.223  1.0
  O  O5  1  0.500  0.000  0.777  1.0
  O  O6  1  0.000  0.500  0.223  1.0
  O  O7  1  0.000  0.500  0.777  1.0
  O  O8  1  0.500  0.500  0.500  1.0
[/CIF]
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