The structure described by Dy2SiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form distorted DyO7 hexagonal pyramids that share corners with two equivalent Dy(2)O7 hexagonal pyramids, corners with three equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Dy(1)O7 hexagonal pyramids, edges with three equivalent Dy(2)O7 hexagonal pyramids, and edges with two equivalent Si(1)O5 trigonal bipyramids. In the second Dy site, Dy(2) is bonded to one O(4), one O(5), two equivalent O(3), and three equivalent O(1) atoms to form distorted DyO7 hexagonal pyramids that share corners with two equivalent Dy(1)O7 hexagonal pyramids,  a cornercorner with one Si(1)O5 trigonal bipyramid, edges with three equivalent Dy(1)O7 hexagonal pyramids, edges with four equivalent Dy(2)O7 hexagonal pyramids, and edges with two equivalent Si(1)O5 trigonal bipyramids. Si(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted SiO5 trigonal bipyramids that share  a cornercorner with one Dy(2)O7 hexagonal pyramid, corners with three equivalent Dy(1)O7 hexagonal pyramids, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Dy(1)O7 hexagonal pyramids, and edges with two equivalent Dy(2)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Dy(1) and three equivalent Dy(2) atoms to form ODy4 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with five equivalent O(3)Dy3Si tetrahedra, corners with five equivalent O(5)Dy3Si tetrahedra,  an edgeedge with one O(3)Dy3Si tetrahedra, and edges with two equivalent O(1)Dy4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Dy(1) and one Si(1) atom. In the third O site, O(3) is bonded to one Dy(1), two equivalent Dy(2), and one Si(1) atom to form distorted ODy3Si tetrahedra that share  a cornercorner with one O(5)Dy3Si tetrahedra, corners with two equivalent O(3)Dy3Si tetrahedra, corners with five equivalent O(1)Dy4 tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with two equivalent O(5)Dy3Si tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Dy(1), one Dy(2), and two equivalent Si(1) atoms. In the fifth O site, O(5) is bonded to one Dy(2), two equivalent Dy(1), and one Si(1) atom to form ODy3Si tetrahedra that share  a cornercorner with one O(3)Dy3Si tetrahedra, corners with two equivalent O(5)Dy3Si tetrahedra, corners with five equivalent O(1)Dy4 tetrahedra, and edges with two equivalent O(3)Dy3Si tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Dy2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.678
_cell_length_b   10.191
_cell_length_c   10.818
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   405.509
_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
  Dy  Dy0  1  0.250  0.101  0.283  1.0
  Dy  Dy1  1  0.250  0.140  0.946  1.0
  Dy  Dy2  1  0.750  0.360  0.446  1.0
  Dy  Dy3  1  0.750  0.399  0.783  1.0
  Dy  Dy4  1  0.250  0.601  0.217  1.0
  Dy  Dy5  1  0.250  0.640  0.554  1.0
  Dy  Dy6  1  0.750  0.860  0.054  1.0
  Dy  Dy7  1  0.750  0.899  0.717  1.0
  Si  Si8  1  0.250  0.181  0.625  1.0
  Si  Si9  1  0.750  0.319  0.125  1.0
  Si  Si10  1  0.250  0.681  0.875  1.0
  Si  Si11  1  0.750  0.819  0.375  1.0
  O  O12  1  0.750  0.010  0.896  1.0
  O  O13  1  0.250  0.023  0.656  1.0
  O  O14  1  0.250  0.221  0.472  1.0
  O  O15  1  0.750  0.224  0.622  1.0
  O  O16  1  0.750  0.235  0.263  1.0
  O  O17  1  0.250  0.265  0.763  1.0
  O  O18  1  0.250  0.276  0.122  1.0
  O  O19  1  0.750  0.279  0.972  1.0
  O  O20  1  0.750  0.477  0.156  1.0
  O  O21  1  0.250  0.490  0.396  1.0
  O  O22  1  0.750  0.510  0.604  1.0
  O  O23  1  0.250  0.523  0.844  1.0
  O  O24  1  0.250  0.721  0.028  1.0
  O  O25  1  0.750  0.724  0.878  1.0
  O  O26  1  0.750  0.735  0.237  1.0
  O  O27  1  0.250  0.765  0.737  1.0
  O  O28  1  0.250  0.776  0.378  1.0
  O  O29  1  0.750  0.779  0.528  1.0
  O  O30  1  0.750  0.977  0.344  1.0
  O  O31  1  0.250  0.990  0.104  1.0
[/CIF]
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The structure described by Dy2SiO5 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Dy sites. In the first Dy site, Dy(1) is bonded to one O(1), one O(3), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form distorted DyO7 hexagonal pyramids that share corners with two equivalent Dy(2)O7 hexagonal pyramids, corners with three equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Dy(1)O7 hexagonal pyramids, edges with three equivalent Dy(2)O7 hexagonal pyramids, and edges with two equivalent Si(1)O5 trigonal bipyramids. In the second Dy site, Dy(2) is bonded to one O(4), one O(5), two equivalent O(3), and three equivalent O(1) atoms to form distorted DyO7 hexagonal pyramids that share corners with two equivalent Dy(1)O7 hexagonal pyramids,  a cornercorner with one Si(1)O5 trigonal bipyramid, edges with three equivalent Dy(1)O7 hexagonal pyramids, edges with four equivalent Dy(2)O7 hexagonal pyramids, and edges with two equivalent Si(1)O5 trigonal bipyramids. Si(1) is bonded to one O(2), one O(3), one O(5), and two equivalent O(4) atoms to form distorted SiO5 trigonal bipyramids that share  a cornercorner with one Dy(2)O7 hexagonal pyramid, corners with three equivalent Dy(1)O7 hexagonal pyramids, corners with two equivalent Si(1)O5 trigonal bipyramids, edges with two equivalent Dy(1)O7 hexagonal pyramids, and edges with two equivalent Dy(2)O7 hexagonal pyramids. There are five inequivalent O sites. In the first O site, O(1) is bonded to one Dy(1) and three equivalent Dy(2) atoms to form ODy4 tetrahedra that share corners with two equivalent O(1)Dy4 tetrahedra, corners with five equivalent O(3)Dy3Si tetrahedra, corners with five equivalent O(5)Dy3Si tetrahedra,  an edgeedge with one O(3)Dy3Si tetrahedra, and edges with two equivalent O(1)Dy4 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Dy(1) and one Si(1) atom. In the third O site, O(3) is bonded to one Dy(1), two equivalent Dy(2), and one Si(1) atom to form distorted ODy3Si tetrahedra that share  a cornercorner with one O(5)Dy3Si tetrahedra, corners with two equivalent O(3)Dy3Si tetrahedra, corners with five equivalent O(1)Dy4 tetrahedra,  an edgeedge with one O(1)Dy4 tetrahedra, and edges with two equivalent O(5)Dy3Si tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Dy(1), one Dy(2), and two equivalent Si(1) atoms. In the fifth O site, O(5) is bonded to one Dy(2), two equivalent Dy(1), and one Si(1) atom to form ODy3Si tetrahedra that share  a cornercorner with one O(3)Dy3Si tetrahedra, corners with two equivalent O(5)Dy3Si tetrahedra, corners with five equivalent O(1)Dy4 tetrahedra, and edges with two equivalent O(3)Dy3Si tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_Dy2SiO5
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   3.678
_cell_length_b   10.191
_cell_length_c   10.818
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   405.509
_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
  Dy  Dy0  1  0.250  0.101  0.283  1.0
  Dy  Dy1  1  0.250  0.140  0.946  1.0
  Dy  Dy2  1  0.750  0.360  0.446  1.0
  Dy  Dy3  1  0.750  0.399  0.783  1.0
  Dy  Dy4  1  0.250  0.601  0.217  1.0
  Dy  Dy5  1  0.250  0.640  0.554  1.0
  Dy  Dy6  1  0.750  0.860  0.054  1.0
  Dy  Dy7  1  0.750  0.899  0.717  1.0
  Si  Si8  1  0.250  0.181  0.625  1.0
  Si  Si9  1  0.750  0.319  0.125  1.0
  Si  Si10  1  0.250  0.681  0.875  1.0
  Si  Si11  1  0.750  0.819  0.375  1.0
  O  O12  1  0.750  0.010  0.896  1.0
  O  O13  1  0.250  0.023  0.656  1.0
  O  O14  1  0.250  0.221  0.472  1.0
  O  O15  1  0.750  0.224  0.622  1.0
  O  O16  1  0.750  0.235  0.263  1.0
  O  O17  1  0.250  0.265  0.763  1.0
  O  O18  1  0.250  0.276  0.122  1.0
  O  O19  1  0.750  0.279  0.972  1.0
  O  O20  1  0.750  0.477  0.156  1.0
  O  O21  1  0.250  0.490  0.396  1.0
  O  O22  1  0.750  0.510  0.604  1.0
  O  O23  1  0.250  0.523  0.844  1.0
  O  O24  1  0.250  0.721  0.028  1.0
  O  O25  1  0.750  0.724  0.878  1.0
  O  O26  1  0.750  0.735  0.237  1.0
  O  O27  1  0.250  0.765  0.737  1.0
  O  O28  1  0.250  0.776  0.378  1.0
  O  O29  1  0.750  0.779  0.528  1.0
  O  O30  1  0.750  0.977  0.344  1.0
  O  O31  1  0.250  0.990  0.104  1.0
[/CIF]
.