The structure described by Er2SiO5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to one O(4), three equivalent O(1), and three equivalent O(3) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Si(1) is bonded in a tetrahedral geometry to one O(2), one O(3), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Er(2) and three equivalent Er(1) atoms to form a mixture of corner and edge-sharing OEr4 tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Er(2) and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to three equivalent Er(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Er(1), two equivalent Er(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Er(2) and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.614
_cell_length_b   6.690
_cell_length_c   9.019
_cell_angle_alpha   90.000
_cell_angle_beta   103.491
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   388.029
_cell_formula_units_Z   4
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  0.269  0.121  0.469  1.0
  Er  Er1  1  0.231  0.621  0.531  1.0
  Er  Er2  1  0.731  0.879  0.531  1.0
  Er  Er3  1  0.769  0.379  0.469  1.0
  Er  Er4  1  0.030  0.640  0.862  1.0
  Er  Er5  1  0.470  0.140  0.138  1.0
  Er  Er6  1  0.970  0.360  0.138  1.0
  Er  Er7  1  0.530  0.860  0.862  1.0
  Si  Si8  1  0.012  0.094  0.799  1.0
  Si  Si9  1  0.488  0.594  0.201  1.0
  Si  Si10  1  0.988  0.906  0.201  1.0
  Si  Si11  1  0.512  0.406  0.799  1.0
  O  O12  1  0.432  0.880  0.610  1.0
  O  O13  1  0.068  0.380  0.390  1.0
  O  O14  1  0.568  0.120  0.390  1.0
  O  O15  1  0.932  0.620  0.610  1.0
  O  O16  1  0.011  0.292  0.898  1.0
  O  O17  1  0.489  0.792  0.102  1.0
  O  O18  1  0.989  0.708  0.102  1.0
  O  O19  1  0.511  0.208  0.898  1.0
  O  O20  1  0.982  0.142  0.615  1.0
  O  O21  1  0.518  0.642  0.385  1.0
  O  O22  1  0.018  0.858  0.385  1.0
  O  O23  1  0.482  0.358  0.615  1.0
  O  O24  1  0.318  0.565  0.789  1.0
  O  O25  1  0.182  0.065  0.211  1.0
  O  O26  1  0.682  0.435  0.211  1.0
  O  O27  1  0.818  0.935  0.789  1.0
  O  O28  1  0.702  0.559  0.862  1.0
  O  O29  1  0.798  0.059  0.138  1.0
  O  O30  1  0.298  0.441  0.138  1.0
  O  O31  1  0.202  0.941  0.862  1.0
[/CIF]
.
The structure described by Er2SiO5 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Er sites. In the first Er site, Er(1) is bonded in a 7-coordinate geometry to one O(4), three equivalent O(1), and three equivalent O(3) atoms. In the second Er site, Er(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms. Si(1) is bonded in a tetrahedral geometry to one O(2), one O(3), one O(4), and one O(5) atom. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Er(2) and three equivalent Er(1) atoms to form a mixture of corner and edge-sharing OEr4 tetrahedra. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Er(2) and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to three equivalent Er(1) and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Er(1), two equivalent Er(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Er(2) and one Si(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Er2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.614
_cell_length_b   6.690
_cell_length_c   9.019
_cell_angle_alpha   90.000
_cell_angle_beta   103.491
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   388.029
_cell_formula_units_Z   4
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  0.269  0.121  0.469  1.0
  Er  Er1  1  0.231  0.621  0.531  1.0
  Er  Er2  1  0.731  0.879  0.531  1.0
  Er  Er3  1  0.769  0.379  0.469  1.0
  Er  Er4  1  0.030  0.640  0.862  1.0
  Er  Er5  1  0.470  0.140  0.138  1.0
  Er  Er6  1  0.970  0.360  0.138  1.0
  Er  Er7  1  0.530  0.860  0.862  1.0
  Si  Si8  1  0.012  0.094  0.799  1.0
  Si  Si9  1  0.488  0.594  0.201  1.0
  Si  Si10  1  0.988  0.906  0.201  1.0
  Si  Si11  1  0.512  0.406  0.799  1.0
  O  O12  1  0.432  0.880  0.610  1.0
  O  O13  1  0.068  0.380  0.390  1.0
  O  O14  1  0.568  0.120  0.390  1.0
  O  O15  1  0.932  0.620  0.610  1.0
  O  O16  1  0.011  0.292  0.898  1.0
  O  O17  1  0.489  0.792  0.102  1.0
  O  O18  1  0.989  0.708  0.102  1.0
  O  O19  1  0.511  0.208  0.898  1.0
  O  O20  1  0.982  0.142  0.615  1.0
  O  O21  1  0.518  0.642  0.385  1.0
  O  O22  1  0.018  0.858  0.385  1.0
  O  O23  1  0.482  0.358  0.615  1.0
  O  O24  1  0.318  0.565  0.789  1.0
  O  O25  1  0.182  0.065  0.211  1.0
  O  O26  1  0.682  0.435  0.211  1.0
  O  O27  1  0.818  0.935  0.789  1.0
  O  O28  1  0.702  0.559  0.862  1.0
  O  O29  1  0.798  0.059  0.138  1.0
  O  O30  1  0.298  0.441  0.138  1.0
  O  O31  1  0.202  0.941  0.862  1.0
[/CIF]
.