The material described by MgSc4(Si2O7)2 crystallizes in the orthorhombic Imm2 space group. Mg(1) is bonded to one O(3), one O(4), and four equivalent O(1) atoms to form distorted MgO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra and edges with two equivalent Si(1)O5 square pyramids. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 7-coordinate geometry to one O(5), one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms. In the second Sc site, Sc(2) is bonded in a 8-coordinate geometry to one O(3), one O(5), one O(6), one O(8), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(8), two equivalent O(1), and two equivalent O(2) atoms to form SiO5 square pyramids that share  a cornercorner with one Si(1)O5 square pyramid, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. In the second Si site, Si(2) is bonded to one O(4), one O(7), and two equivalent O(2) atoms to form distorted SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 square pyramids, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 84°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Sc(1), one Sc(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Sc(1), one Sc(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Sc(2) atoms. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Mg(1) and two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form distorted OSc4 trigonal pyramids that share corners with two equivalent O(8)Sc2Si2 tetrahedra and corners with four equivalent O(6)Sc4 tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form OSc4 tetrahedra that share corners with four equivalent O(5)Sc4 trigonal pyramids and  an edgeedge with one O(8)Sc2Si2 tetrahedra. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to two equivalent Sc(1) and two equivalent Si(2) atoms. In the eighth O site, O(8) is bonded to two equivalent Sc(2) and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing OSc2Si2 tetrahedra. is represented by the CIF file [CIF]
data_MgSc4(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.114
_cell_length_b   7.114
_cell_length_c   6.258
_cell_angle_alpha   63.907
_cell_angle_beta   63.907
_cell_angle_gamma   66.437
_symmetry_Int_Tables_number   1
_cell_volume   246.985
_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  0.671  0.671  0.579  1.0
  Sc  Sc1  1  0.968  0.492  0.020  1.0
  Sc  Sc2  1  0.492  0.968  0.020  1.0
  Sc  Sc3  1  0.002  0.002  0.485  1.0
  Sc  Sc4  1  0.002  0.002  0.012  1.0
  Si  Si5  1  0.438  0.045  0.508  1.0
  Si  Si6  1  0.045  0.438  0.508  1.0
  Si  Si7  1  0.458  0.458  0.059  1.0
  Si  Si8  1  0.458  0.458  0.526  1.0
  O  O9  1  0.435  0.853  0.803  1.0
  O  O10  1  0.190  0.533  0.592  1.0
  O  O11  1  0.853  0.435  0.803  1.0
  O  O12  1  0.862  0.862  0.388  1.0
  O  O13  1  0.474  0.474  0.776  1.0
  O  O14  1  0.435  0.853  0.409  1.0
  O  O15  1  0.190  0.533  0.185  1.0
  O  O16  1  0.533  0.190  0.592  1.0
  O  O17  1  0.161  0.161  0.089  1.0
  O  O18  1  0.861  0.861  0.889  1.0
  O  O19  1  0.853  0.435  0.409  1.0
  O  O20  1  0.549  0.549  0.201  1.0
  O  O21  1  0.167  0.167  0.583  1.0
  O  O22  1  0.533  0.190  0.185  1.0
[/CIF]
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The material described by MgSc4(Si2O7)2 crystallizes in the orthorhombic Imm2 space group. Mg(1) is bonded to one O(3), one O(4), and four equivalent O(1) atoms to form distorted MgO6 octahedra that share corners with two equivalent Si(2)O4 tetrahedra and edges with two equivalent Si(1)O5 square pyramids. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 7-coordinate geometry to one O(5), one O(6), one O(7), two equivalent O(1), and two equivalent O(2) atoms. In the second Sc site, Sc(2) is bonded in a 8-coordinate geometry to one O(3), one O(5), one O(6), one O(8), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(8), two equivalent O(1), and two equivalent O(2) atoms to form SiO5 square pyramids that share  a cornercorner with one Si(1)O5 square pyramid, corners with two equivalent Si(2)O4 tetrahedra, and  an edgeedge with one Mg(1)O6 octahedra. In the second Si site, Si(2) is bonded to one O(4), one O(7), and two equivalent O(2) atoms to form distorted SiO4 tetrahedra that share  a cornercorner with one Mg(1)O6 octahedra, corners with two equivalent Si(1)O5 square pyramids, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 84°. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Sc(1), one Sc(2), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Sc(1), one Sc(2), one Si(1), and one Si(2) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to one Mg(1) and two equivalent Sc(2) atoms. In the fourth O site, O(4) is bonded in a T-shaped geometry to one Mg(1) and two equivalent Si(2) atoms. In the fifth O site, O(5) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form distorted OSc4 trigonal pyramids that share corners with two equivalent O(8)Sc2Si2 tetrahedra and corners with four equivalent O(6)Sc4 tetrahedra. In the sixth O site, O(6) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form OSc4 tetrahedra that share corners with four equivalent O(5)Sc4 trigonal pyramids and  an edgeedge with one O(8)Sc2Si2 tetrahedra. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to two equivalent Sc(1) and two equivalent Si(2) atoms. In the eighth O site, O(8) is bonded to two equivalent Sc(2) and two equivalent Si(1) atoms to form a mixture of distorted corner and edge-sharing OSc2Si2 tetrahedra. is represented by the CIF file [CIF]
data_MgSc4(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.114
_cell_length_b   7.114
_cell_length_c   6.258
_cell_angle_alpha   63.907
_cell_angle_beta   63.907
_cell_angle_gamma   66.437
_symmetry_Int_Tables_number   1
_cell_volume   246.985
_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  0.671  0.671  0.579  1.0
  Sc  Sc1  1  0.968  0.492  0.020  1.0
  Sc  Sc2  1  0.492  0.968  0.020  1.0
  Sc  Sc3  1  0.002  0.002  0.485  1.0
  Sc  Sc4  1  0.002  0.002  0.012  1.0
  Si  Si5  1  0.438  0.045  0.508  1.0
  Si  Si6  1  0.045  0.438  0.508  1.0
  Si  Si7  1  0.458  0.458  0.059  1.0
  Si  Si8  1  0.458  0.458  0.526  1.0
  O  O9  1  0.435  0.853  0.803  1.0
  O  O10  1  0.190  0.533  0.592  1.0
  O  O11  1  0.853  0.435  0.803  1.0
  O  O12  1  0.862  0.862  0.388  1.0
  O  O13  1  0.474  0.474  0.776  1.0
  O  O14  1  0.435  0.853  0.409  1.0
  O  O15  1  0.190  0.533  0.185  1.0
  O  O16  1  0.533  0.190  0.592  1.0
  O  O17  1  0.161  0.161  0.089  1.0
  O  O18  1  0.861  0.861  0.889  1.0
  O  O19  1  0.853  0.435  0.409  1.0
  O  O20  1  0.549  0.549  0.201  1.0
  O  O21  1  0.167  0.167  0.583  1.0
  O  O22  1  0.533  0.190  0.185  1.0
[/CIF]
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