The compound described by Tm2Si2O7 crystallizes in the monoclinic C2/m space group. Tm(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form distorted TmO6 pentagonal pyramids that share corners with six equivalent Si(1)O4 tetrahedra and edges with three equivalent Tm(1)O6 pentagonal pyramids. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with six equivalent Tm(1)O6 pentagonal pyramids and  a cornercorner with one Si(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Tm(1) and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Tm(1) and one Si(1) atom. is represented by the CIF file [CIF]
data_Tm2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.718
_cell_length_b   5.568
_cell_length_c   5.568
_cell_angle_alpha   105.115
_cell_angle_beta   97.267
_cell_angle_gamma   97.267
_symmetry_Int_Tables_number   1
_cell_volume   138.082
_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
  Tm  Tm0  1  0.500  0.307  0.693  1.0
  Tm  Tm1  1  0.500  0.693  0.307  1.0
  Si  Si2  1  0.911  0.220  0.220  1.0
  Si  Si3  1  0.089  0.780  0.780  1.0
  O  O4  1  0.216  0.384  0.384  1.0
  O  O5  1  0.784  0.616  0.616  1.0
  O  O6  1  0.000  0.000  0.000  1.0
  O  O7  1  0.720  0.085  0.388  1.0
  O  O8  1  0.720  0.388  0.085  1.0
  O  O9  1  0.280  0.915  0.612  1.0
  O  O10  1  0.280  0.612  0.915  1.0
[/CIF]
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The compound described by Tm2Si2O7 crystallizes in the monoclinic C2/m space group. Tm(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form distorted TmO6 pentagonal pyramids that share corners with six equivalent Si(1)O4 tetrahedra and edges with three equivalent Tm(1)O6 pentagonal pyramids. Si(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with six equivalent Tm(1)O6 pentagonal pyramids and  a cornercorner with one Si(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Tm(1) and one Si(1) atom. In the second O site, O(2) is bonded in a linear geometry to two equivalent Si(1) atoms. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Tm(1) and one Si(1) atom. is represented by the CIF file [CIF]
data_Tm2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.718
_cell_length_b   5.568
_cell_length_c   5.568
_cell_angle_alpha   105.115
_cell_angle_beta   97.267
_cell_angle_gamma   97.267
_symmetry_Int_Tables_number   1
_cell_volume   138.082
_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
  Tm  Tm0  1  0.500  0.307  0.693  1.0
  Tm  Tm1  1  0.500  0.693  0.307  1.0
  Si  Si2  1  0.911  0.220  0.220  1.0
  Si  Si3  1  0.089  0.780  0.780  1.0
  O  O4  1  0.216  0.384  0.384  1.0
  O  O5  1  0.784  0.616  0.616  1.0
  O  O6  1  0.000  0.000  0.000  1.0
  O  O7  1  0.720  0.085  0.388  1.0
  O  O8  1  0.720  0.388  0.085  1.0
  O  O9  1  0.280  0.915  0.612  1.0
  O  O10  1  0.280  0.612  0.915  1.0
[/CIF]
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