The crystal structure described by Er2Si2O7 crystallizes in the monoclinic P2_1/c space group. Er(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted ErO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with three equivalent Er(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with six equivalent Er(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-61°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Er(1) and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Er(1) and one Si(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Er(1) and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.714
_cell_length_b   4.698
_cell_length_c   5.525
_cell_angle_alpha   83.867
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   276.468
_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
  Er  Er0  1  0.151  0.110  0.593  1.0
  Er  Er1  1  0.651  0.890  0.907  1.0
  Er  Er2  1  0.849  0.890  0.407  1.0
  Er  Er3  1  0.349  0.110  0.093  1.0
  Si  Si4  1  0.113  0.640  0.145  1.0
  Si  Si5  1  0.613  0.360  0.355  1.0
  Si  Si6  1  0.887  0.360  0.855  1.0
  Si  Si7  1  0.387  0.640  0.645  1.0
  O  O8  1  0.204  0.380  0.255  1.0
  O  O9  1  0.704  0.620  0.245  1.0
  O  O10  1  0.796  0.620  0.745  1.0
  O  O11  1  0.296  0.380  0.755  1.0
  O  O12  1  0.184  0.877  0.959  1.0
  O  O13  1  0.684  0.123  0.541  1.0
  O  O14  1  0.816  0.123  0.041  1.0
  O  O15  1  0.316  0.877  0.459  1.0
  O  O16  1  0.500  0.500  0.500  1.0
  O  O17  1  0.000  0.500  0.000  1.0
  O  O18  1  0.449  0.796  0.868  1.0
  O  O19  1  0.949  0.204  0.632  1.0
  O  O20  1  0.551  0.204  0.132  1.0
  O  O21  1  0.051  0.796  0.368  1.0
[/CIF]
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The crystal structure described by Er2Si2O7 crystallizes in the monoclinic P2_1/c space group. Er(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted ErO6 octahedra that share corners with six equivalent Si(1)O4 tetrahedra and edges with three equivalent Er(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with six equivalent Er(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-61°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Er(1) and one Si(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Er(1) and one Si(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Er(1) and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.714
_cell_length_b   4.698
_cell_length_c   5.525
_cell_angle_alpha   83.867
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   276.468
_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
  Er  Er0  1  0.151  0.110  0.593  1.0
  Er  Er1  1  0.651  0.890  0.907  1.0
  Er  Er2  1  0.849  0.890  0.407  1.0
  Er  Er3  1  0.349  0.110  0.093  1.0
  Si  Si4  1  0.113  0.640  0.145  1.0
  Si  Si5  1  0.613  0.360  0.355  1.0
  Si  Si6  1  0.887  0.360  0.855  1.0
  Si  Si7  1  0.387  0.640  0.645  1.0
  O  O8  1  0.204  0.380  0.255  1.0
  O  O9  1  0.704  0.620  0.245  1.0
  O  O10  1  0.796  0.620  0.745  1.0
  O  O11  1  0.296  0.380  0.755  1.0
  O  O12  1  0.184  0.877  0.959  1.0
  O  O13  1  0.684  0.123  0.541  1.0
  O  O14  1  0.816  0.123  0.041  1.0
  O  O15  1  0.316  0.877  0.459  1.0
  O  O16  1  0.500  0.500  0.500  1.0
  O  O17  1  0.000  0.500  0.000  1.0
  O  O18  1  0.449  0.796  0.868  1.0
  O  O19  1  0.949  0.204  0.632  1.0
  O  O20  1  0.551  0.204  0.132  1.0
  O  O21  1  0.051  0.796  0.368  1.0
[/CIF]
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