The material structure described by Sm2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 8-coordinate geometry to one O(11), one O(13), one O(7), one O(8), two equivalent O(10), and two equivalent O(2) atoms. In the second Sm site, Sm(2) is bonded in a 8-coordinate geometry to one O(11), one O(13), one O(14), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. In the third Sm site, Sm(3) is bonded in a 8-coordinate geometry to one O(12), one O(14), one O(3), one O(6), two equivalent O(4), and two equivalent O(9) atoms. In the fourth Sm site, Sm(4) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(2), and one O(6) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(14), one O(3), and one O(7) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(9) atom to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(2), and one O(8) atom to form corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(11), one O(12), one O(13), and one O(5) atom to form corner-sharing SiO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sm(4), two equivalent Sm(1), and one Si(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sm(2), one Sm(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sm(2), two equivalent Sm(3), and one Si(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Sm(3), one Sm(4), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Sm(1), one Sm(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sm(1), one Sm(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Sm(2), two equivalent Sm(3), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Sm(4), two equivalent Sm(1), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Sm(1), one Sm(2), one Sm(4), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Sm(3), one Sm(4), and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Sm(1), one Sm(2), one Sm(4), and one Si(4) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Sm(2), one Sm(3), one Sm(4), and one Si(1) atom. is represented by the CIF file [CIF]
data_Sm2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.403
_cell_length_b   8.557
_cell_length_c   12.893
_cell_angle_alpha   90.595
_cell_angle_beta   91.389
_cell_angle_gamma   92.567
_symmetry_Int_Tables_number   1
_cell_volume   595.263
_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
  Sm  Sm0  1  0.260  0.896  0.086  1.0
  Sm  Sm1  1  0.740  0.104  0.914  1.0
  Sm  Sm2  1  0.764  0.705  0.264  1.0
  Sm  Sm3  1  0.236  0.295  0.736  1.0
  Sm  Sm4  1  0.754  0.597  0.592  1.0
  Sm  Sm5  1  0.246  0.403  0.408  1.0
  Sm  Sm6  1  0.227  0.824  0.768  1.0
  Sm  Sm7  1  0.773  0.176  0.232  1.0
  Si  Si8  1  0.783  0.494  0.821  1.0
  Si  Si9  1  0.217  0.506  0.179  1.0
  Si  Si10  1  0.209  0.756  0.481  1.0
  Si  Si11  1  0.791  0.244  0.519  1.0
  Si  Si12  1  0.707  0.754  0.973  1.0
  Si  Si13  1  0.293  0.246  0.027  1.0
  Si  Si14  1  0.290  0.003  0.320  1.0
  Si  Si15  1  0.710  0.997  0.680  1.0
  O  O16  1  0.707  0.577  0.929  1.0
  O  O17  1  0.293  0.423  0.071  1.0
  O  O18  1  0.964  0.851  0.947  1.0
  O  O19  1  0.036  0.149  0.053  1.0
  O  O20  1  0.547  0.487  0.740  1.0
  O  O21  1  0.453  0.513  0.260  1.0
  O  O22  1  0.455  0.657  0.470  1.0
  O  O23  1  0.545  0.343  0.530  1.0
  O  O24  1  0.244  0.931  0.434  1.0
  O  O25  1  0.756  0.069  0.566  1.0
  O  O26  1  0.110  0.769  0.598  1.0
  O  O27  1  0.890  0.231  0.402  1.0
  O  O28  1  0.888  0.324  0.841  1.0
  O  O29  1  0.112  0.676  0.159  1.0
  O  O30  1  0.636  0.760  0.093  1.0
  O  O31  1  0.364  0.240  0.907  1.0
  O  O32  1  0.008  0.354  0.581  1.0
  O  O33  1  0.992  0.646  0.419  1.0
  O  O34  1  0.513  0.142  0.081  1.0
  O  O35  1  0.487  0.858  0.919  1.0
  O  O36  1  0.488  0.082  0.739  1.0
  O  O37  1  0.512  0.918  0.261  1.0
  O  O38  1  0.618  0.815  0.680  1.0
  O  O39  1  0.382  0.185  0.320  1.0
  O  O40  1  0.961  0.030  0.753  1.0
  O  O41  1  0.039  0.970  0.247  1.0
  O  O42  1  0.993  0.412  0.237  1.0
  O  O43  1  0.007  0.588  0.763  1.0
[/CIF]
.
The material structure described by Sm2Si2O7 crystallizes in the triclinic P-1 space group. There are four inequivalent Sm sites. In the first Sm site, Sm(1) is bonded in a 8-coordinate geometry to one O(11), one O(13), one O(7), one O(8), two equivalent O(10), and two equivalent O(2) atoms. In the second Sm site, Sm(2) is bonded in a 8-coordinate geometry to one O(11), one O(13), one O(14), one O(3), one O(4), one O(7), one O(8), and one O(9) atom. In the third Sm site, Sm(3) is bonded in a 8-coordinate geometry to one O(12), one O(14), one O(3), one O(6), two equivalent O(4), and two equivalent O(9) atoms. In the fourth Sm site, Sm(4) is bonded in a 7-coordinate geometry to one O(10), one O(11), one O(12), one O(13), one O(14), one O(2), and one O(6) atom. There are four inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(14), one O(3), and one O(7) atom to form corner-sharing SiO4 tetrahedra. In the second Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(9) atom to form corner-sharing SiO4 tetrahedra. In the third Si site, Si(3) is bonded to one O(1), one O(10), one O(2), and one O(8) atom to form corner-sharing SiO4 tetrahedra. In the fourth Si site, Si(4) is bonded to one O(11), one O(12), one O(13), and one O(5) atom to form corner-sharing SiO4 tetrahedra. There are fourteen inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Si(1) and one Si(3) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Sm(4), two equivalent Sm(1), and one Si(3) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Sm(2), one Sm(3), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Sm(2), two equivalent Sm(3), and one Si(2) atom. In the fifth O site, O(5) is bonded in a bent 150 degrees geometry to one Si(2) and one Si(4) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Sm(3), one Sm(4), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal planar geometry to one Sm(1), one Sm(2), and one Si(1) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Sm(1), one Sm(2), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Sm(2), two equivalent Sm(3), and one Si(2) atom. In the tenth O site, O(10) is bonded in a 4-coordinate geometry to one Sm(4), two equivalent Sm(1), and one Si(3) atom. In the eleventh O site, O(11) is bonded in a 4-coordinate geometry to one Sm(1), one Sm(2), one Sm(4), and one Si(4) atom. In the twelfth O site, O(12) is bonded in a distorted trigonal planar geometry to one Sm(3), one Sm(4), and one Si(4) atom. In the thirteenth O site, O(13) is bonded in a 4-coordinate geometry to one Sm(1), one Sm(2), one Sm(4), and one Si(4) atom. In the fourteenth O site, O(14) is bonded in a 4-coordinate geometry to one Sm(2), one Sm(3), one Sm(4), and one Si(1) atom. is represented by the CIF file [CIF]
data_Sm2Si2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.403
_cell_length_b   8.557
_cell_length_c   12.893
_cell_angle_alpha   90.595
_cell_angle_beta   91.389
_cell_angle_gamma   92.567
_symmetry_Int_Tables_number   1
_cell_volume   595.263
_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
  Sm  Sm0  1  0.260  0.896  0.086  1.0
  Sm  Sm1  1  0.740  0.104  0.914  1.0
  Sm  Sm2  1  0.764  0.705  0.264  1.0
  Sm  Sm3  1  0.236  0.295  0.736  1.0
  Sm  Sm4  1  0.754  0.597  0.592  1.0
  Sm  Sm5  1  0.246  0.403  0.408  1.0
  Sm  Sm6  1  0.227  0.824  0.768  1.0
  Sm  Sm7  1  0.773  0.176  0.232  1.0
  Si  Si8  1  0.783  0.494  0.821  1.0
  Si  Si9  1  0.217  0.506  0.179  1.0
  Si  Si10  1  0.209  0.756  0.481  1.0
  Si  Si11  1  0.791  0.244  0.519  1.0
  Si  Si12  1  0.707  0.754  0.973  1.0
  Si  Si13  1  0.293  0.246  0.027  1.0
  Si  Si14  1  0.290  0.003  0.320  1.0
  Si  Si15  1  0.710  0.997  0.680  1.0
  O  O16  1  0.707  0.577  0.929  1.0
  O  O17  1  0.293  0.423  0.071  1.0
  O  O18  1  0.964  0.851  0.947  1.0
  O  O19  1  0.036  0.149  0.053  1.0
  O  O20  1  0.547  0.487  0.740  1.0
  O  O21  1  0.453  0.513  0.260  1.0
  O  O22  1  0.455  0.657  0.470  1.0
  O  O23  1  0.545  0.343  0.530  1.0
  O  O24  1  0.244  0.931  0.434  1.0
  O  O25  1  0.756  0.069  0.566  1.0
  O  O26  1  0.110  0.769  0.598  1.0
  O  O27  1  0.890  0.231  0.402  1.0
  O  O28  1  0.888  0.324  0.841  1.0
  O  O29  1  0.112  0.676  0.159  1.0
  O  O30  1  0.636  0.760  0.093  1.0
  O  O31  1  0.364  0.240  0.907  1.0
  O  O32  1  0.008  0.354  0.581  1.0
  O  O33  1  0.992  0.646  0.419  1.0
  O  O34  1  0.513  0.142  0.081  1.0
  O  O35  1  0.487  0.858  0.919  1.0
  O  O36  1  0.488  0.082  0.739  1.0
  O  O37  1  0.512  0.918  0.261  1.0
  O  O38  1  0.618  0.815  0.680  1.0
  O  O39  1  0.382  0.185  0.320  1.0
  O  O40  1  0.961  0.030  0.753  1.0
  O  O41  1  0.039  0.970  0.247  1.0
  O  O42  1  0.993  0.412  0.237  1.0
  O  O43  1  0.007  0.588  0.763  1.0
[/CIF]
.