The material described by Dy2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(2), one O(3), one O(4), one O(7), and one O(9) atom. In the second Dy site, Dy(2) is bonded to one O(12), one O(13), one O(14), one O(3), one O(6), and one O(7) atom to form distorted DyO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with three equivalent Si(2)O4 tetrahedra. In the third Dy site, Dy(3) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(13), one O(14), one O(5), one O(7), and two equivalent O(6) atoms. In the fourth Dy site, Dy(4) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(4), one O(5), one O(9), and two equivalent O(2) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Dy(2)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-66°. In the second Si site, Si(2) is bonded to one O(12), one O(13), one O(14), and one O(8) atom to form SiO4 tetrahedra that share corners with three equivalent Dy(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 64-65°. In the third Si site, Si(3) is bonded to one O(10), one O(11), one O(12), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Dy(2)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. In the fourth Si site, Si(4) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Dy(2)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Dy(1), one Dy(3), one Dy(4), and one Si(4) atom. In the second O site, O(2) is bonded to one Dy(1), two equivalent Dy(4), and one Si(4) atom to form distorted edge-sharing ODy3Si tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Dy(1), one Dy(2), and one Si(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(4), and one Si(4) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Dy(3), one Dy(4), and one Si(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Dy(2), two equivalent Dy(3), and one Si(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Dy(1), one Dy(2), one Dy(3), and one Si(1) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(4), and one Si(3) atom. In the tenth O site, O(10) is bonded in a 1-coordinate geometry to one Dy(1), one Dy(3), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(4), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Dy(2), one Si(2), and one Si(3) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Dy(2), one Dy(3), and one Si(2) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Dy(2), one Dy(3), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Dy2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.661
_cell_length_b   6.694
_cell_length_c   12.154
_cell_angle_alpha   94.322
_cell_angle_beta   91.320
_cell_angle_gamma   91.973
_symmetry_Int_Tables_number   1
_cell_volume   539.890
_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  0.674  0.173  0.891  1.0
  Dy  Dy1  1  0.326  0.827  0.109  1.0
  Dy  Dy2  1  0.368  0.217  0.634  1.0
  Dy  Dy3  1  0.632  0.783  0.366  1.0
  Dy  Dy4  1  0.882  0.910  0.644  1.0
  Dy  Dy5  1  0.118  0.090  0.356  1.0
  Dy  Dy6  1  0.949  0.673  0.885  1.0
  Dy  Dy7  1  0.051  0.327  0.115  1.0
  Si  Si8  1  0.145  0.626  0.379  1.0
  Si  Si9  1  0.855  0.374  0.621  1.0
  Si  Si10  1  0.377  0.725  0.594  1.0
  Si  Si11  1  0.623  0.275  0.406  1.0
  Si  Si12  1  0.487  0.666  0.825  1.0
  Si  Si13  1  0.513  0.334  0.175  1.0
  Si  Si14  1  0.155  0.148  0.885  1.0
  Si  Si15  1  0.845  0.852  0.115  1.0
  O  O16  1  0.001  0.986  0.815  1.0
  O  O17  1  0.999  0.014  0.185  1.0
  O  O18  1  1.000  0.333  0.918  1.0
  O  O19  1  0.000  0.667  0.082  1.0
  O  O20  1  0.348  0.209  0.815  1.0
  O  O21  1  0.652  0.791  0.185  1.0
  O  O22  1  0.230  0.084  0.005  1.0
  O  O23  1  0.770  0.916  0.995  1.0
  O  O24  1  0.076  0.416  0.310  1.0
  O  O25  1  0.924  0.584  0.690  1.0
  O  O26  1  0.963  0.772  0.420  1.0
  O  O27  1  0.037  0.228  0.580  1.0
  O  O28  1  0.290  0.782  0.312  1.0
  O  O29  1  0.710  0.218  0.688  1.0
  O  O30  1  0.284  0.574  0.489  1.0
  O  O31  1  0.716  0.426  0.511  1.0
  O  O32  1  0.355  0.489  0.126  1.0
  O  O33  1  0.645  0.511  0.874  1.0
  O  O34  1  0.382  0.137  0.211  1.0
  O  O35  1  0.618  0.863  0.789  1.0
  O  O36  1  0.700  0.294  0.095  1.0
  O  O37  1  0.300  0.706  0.905  1.0
  O  O38  1  0.600  0.432  0.306  1.0
  O  O39  1  0.400  0.568  0.694  1.0
  O  O40  1  0.414  0.174  0.448  1.0
  O  O41  1  0.586  0.826  0.552  1.0
  O  O42  1  0.774  0.096  0.377  1.0
  O  O43  1  0.226  0.904  0.623  1.0
[/CIF]
.
The material described by Dy2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Dy sites. In the first Dy site, Dy(1) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(11), one O(2), one O(3), one O(4), one O(7), and one O(9) atom. In the second Dy site, Dy(2) is bonded to one O(12), one O(13), one O(14), one O(3), one O(6), and one O(7) atom to form distorted DyO6 octahedra that share  a cornercorner with one Si(3)O4 tetrahedra,  a cornercorner with one Si(4)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with three equivalent Si(2)O4 tetrahedra. In the third Dy site, Dy(3) is bonded in a 8-coordinate geometry to one O(1), one O(10), one O(13), one O(14), one O(5), one O(7), and two equivalent O(6) atoms. In the fourth Dy site, Dy(4) is bonded in a 7-coordinate geometry to one O(1), one O(11), one O(4), one O(5), one O(9), and two equivalent O(2) atoms. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Dy(2)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-66°. In the second Si site, Si(2) is bonded to one O(12), one O(13), one O(14), and one O(8) atom to form SiO4 tetrahedra that share corners with three equivalent Dy(2)O6 octahedra,  a cornercorner with one Si(1)O4 tetrahedra, and  a cornercorner with one Si(3)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 64-65°. In the third Si site, Si(3) is bonded to one O(10), one O(11), one O(12), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Dy(2)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 55°. In the fourth Si site, Si(4) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share  a cornercorner with one Dy(2)O6 octahedra. The corner-sharing octahedral tilt angles are 52°. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Dy(1), one Dy(3), one Dy(4), and one Si(4) atom. In the second O site, O(2) is bonded to one Dy(1), two equivalent Dy(4), and one Si(4) atom to form distorted edge-sharing ODy3Si tetrahedra. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to one Dy(1), one Dy(2), and one Si(4) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(4), and one Si(4) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Dy(3), one Dy(4), and one Si(1) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Dy(2), two equivalent Dy(3), and one Si(1) atom. In the seventh O site, O(7) is bonded in a 4-coordinate geometry to one Dy(1), one Dy(2), one Dy(3), and one Si(1) atom. In the eighth O site, O(8) is bonded in a bent 120 degrees geometry to one Si(1) and one Si(2) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(4), and one Si(3) atom. In the tenth O site, O(10) is bonded in a 1-coordinate geometry to one Dy(1), one Dy(3), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Dy(1), one Dy(4), and one Si(3) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Dy(2), one Si(2), and one Si(3) atom. In the thirteenth O site, O(13) is bonded in a distorted trigonal planar geometry to one Dy(2), one Dy(3), and one Si(2) atom. In the fourteenth O site, O(14) is bonded in a distorted trigonal planar geometry to one Dy(2), one Dy(3), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Dy2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.661
_cell_length_b   6.694
_cell_length_c   12.154
_cell_angle_alpha   94.322
_cell_angle_beta   91.320
_cell_angle_gamma   91.973
_symmetry_Int_Tables_number   1
_cell_volume   539.890
_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  0.674  0.173  0.891  1.0
  Dy  Dy1  1  0.326  0.827  0.109  1.0
  Dy  Dy2  1  0.368  0.217  0.634  1.0
  Dy  Dy3  1  0.632  0.783  0.366  1.0
  Dy  Dy4  1  0.882  0.910  0.644  1.0
  Dy  Dy5  1  0.118  0.090  0.356  1.0
  Dy  Dy6  1  0.949  0.673  0.885  1.0
  Dy  Dy7  1  0.051  0.327  0.115  1.0
  Si  Si8  1  0.145  0.626  0.379  1.0
  Si  Si9  1  0.855  0.374  0.621  1.0
  Si  Si10  1  0.377  0.725  0.594  1.0
  Si  Si11  1  0.623  0.275  0.406  1.0
  Si  Si12  1  0.487  0.666  0.825  1.0
  Si  Si13  1  0.513  0.334  0.175  1.0
  Si  Si14  1  0.155  0.148  0.885  1.0
  Si  Si15  1  0.845  0.852  0.115  1.0
  O  O16  1  0.001  0.986  0.815  1.0
  O  O17  1  0.999  0.014  0.185  1.0
  O  O18  1  1.000  0.333  0.918  1.0
  O  O19  1  0.000  0.667  0.082  1.0
  O  O20  1  0.348  0.209  0.815  1.0
  O  O21  1  0.652  0.791  0.185  1.0
  O  O22  1  0.230  0.084  0.005  1.0
  O  O23  1  0.770  0.916  0.995  1.0
  O  O24  1  0.076  0.416  0.310  1.0
  O  O25  1  0.924  0.584  0.690  1.0
  O  O26  1  0.963  0.772  0.420  1.0
  O  O27  1  0.037  0.228  0.580  1.0
  O  O28  1  0.290  0.782  0.312  1.0
  O  O29  1  0.710  0.218  0.688  1.0
  O  O30  1  0.284  0.574  0.489  1.0
  O  O31  1  0.716  0.426  0.511  1.0
  O  O32  1  0.355  0.489  0.126  1.0
  O  O33  1  0.645  0.511  0.874  1.0
  O  O34  1  0.382  0.137  0.211  1.0
  O  O35  1  0.618  0.863  0.789  1.0
  O  O36  1  0.700  0.294  0.095  1.0
  O  O37  1  0.300  0.706  0.905  1.0
  O  O38  1  0.600  0.432  0.306  1.0
  O  O39  1  0.400  0.568  0.694  1.0
  O  O40  1  0.414  0.174  0.448  1.0
  O  O41  1  0.586  0.826  0.552  1.0
  O  O42  1  0.774  0.096  0.377  1.0
  O  O43  1  0.226  0.904  0.623  1.0
[/CIF]
.