The material described by Be2Sm2SiO7 crystallizes in the tetragonal P-42_1m space group. Be(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form BeO4 tetrahedra that share  a cornercorner with one Be(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. Sm(1) is bonded in a 8-coordinate geometry to one O(1), three equivalent O(2), and four equivalent O(3) atoms. Si(1) is bonded to four equivalent O(3) atoms to form SiO4 tetrahedra that share corners with four equivalent Be(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Be(1) and two equivalent Sm(1) atoms to form a mixture of distorted corner and edge-sharing OSm2Be2 tetrahedra. In the second O site, O(2) is bonded to one Be(1) and three equivalent Sm(1) atoms to form distorted OSm3Be tetrahedra that share corners with two equivalent O(1)Sm2Be2 tetrahedra, corners with four equivalent O(2)Sm3Be tetrahedra,  an edgeedge with one O(1)Sm2Be2 tetrahedra, and  an edgeedge with one O(2)Sm3Be tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Be(1), two equivalent Sm(1), and one Si(1) atom. is represented by the CIF card [CIF]
data_Sm2Be2SiO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.444
_cell_length_b   7.444
_cell_length_c   4.861
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   269.344
_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
  Sm  Sm0  1  0.160  0.340  0.509  1.0
  Sm  Sm1  1  0.840  0.660  0.509  1.0
  Sm  Sm2  1  0.660  0.160  0.491  1.0
  Sm  Sm3  1  0.340  0.840  0.491  1.0
  Be  Be4  1  0.635  0.865  0.961  1.0
  Be  Be5  1  0.365  0.135  0.961  1.0
  Be  Be6  1  0.135  0.635  0.039  1.0
  Be  Be7  1  0.865  0.365  0.039  1.0
  Si  Si8  1  0.000  0.000  0.000  1.0
  Si  Si9  1  0.500  0.500  0.000  1.0
  O  O10  1  0.000  0.500  0.179  1.0
  O  O11  1  0.500  0.000  0.821  1.0
  O  O12  1  0.640  0.860  0.287  1.0
  O  O13  1  0.360  0.140  0.287  1.0
  O  O14  1  0.140  0.640  0.713  1.0
  O  O15  1  0.860  0.360  0.713  1.0
  O  O16  1  0.078  0.835  0.194  1.0
  O  O17  1  0.922  0.165  0.194  1.0
  O  O18  1  0.165  0.078  0.806  1.0
  O  O19  1  0.422  0.335  0.806  1.0
  O  O20  1  0.835  0.922  0.806  1.0
  O  O21  1  0.578  0.665  0.806  1.0
  O  O22  1  0.335  0.578  0.194  1.0
  O  O23  1  0.665  0.422  0.194  1.0
[/CIF]
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The material described by Be2Sm2SiO7 crystallizes in the tetragonal P-42_1m space group. Be(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form BeO4 tetrahedra that share  a cornercorner with one Be(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. Sm(1) is bonded in a 8-coordinate geometry to one O(1), three equivalent O(2), and four equivalent O(3) atoms. Si(1) is bonded to four equivalent O(3) atoms to form SiO4 tetrahedra that share corners with four equivalent Be(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Be(1) and two equivalent Sm(1) atoms to form a mixture of distorted corner and edge-sharing OSm2Be2 tetrahedra. In the second O site, O(2) is bonded to one Be(1) and three equivalent Sm(1) atoms to form distorted OSm3Be tetrahedra that share corners with two equivalent O(1)Sm2Be2 tetrahedra, corners with four equivalent O(2)Sm3Be tetrahedra,  an edgeedge with one O(1)Sm2Be2 tetrahedra, and  an edgeedge with one O(2)Sm3Be tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Be(1), two equivalent Sm(1), and one Si(1) atom. is represented by the CIF card [CIF]
data_Sm2Be2SiO7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.444
_cell_length_b   7.444
_cell_length_c   4.861
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   269.344
_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
  Sm  Sm0  1  0.160  0.340  0.509  1.0
  Sm  Sm1  1  0.840  0.660  0.509  1.0
  Sm  Sm2  1  0.660  0.160  0.491  1.0
  Sm  Sm3  1  0.340  0.840  0.491  1.0
  Be  Be4  1  0.635  0.865  0.961  1.0
  Be  Be5  1  0.365  0.135  0.961  1.0
  Be  Be6  1  0.135  0.635  0.039  1.0
  Be  Be7  1  0.865  0.365  0.039  1.0
  Si  Si8  1  0.000  0.000  0.000  1.0
  Si  Si9  1  0.500  0.500  0.000  1.0
  O  O10  1  0.000  0.500  0.179  1.0
  O  O11  1  0.500  0.000  0.821  1.0
  O  O12  1  0.640  0.860  0.287  1.0
  O  O13  1  0.360  0.140  0.287  1.0
  O  O14  1  0.140  0.640  0.713  1.0
  O  O15  1  0.860  0.360  0.713  1.0
  O  O16  1  0.078  0.835  0.194  1.0
  O  O17  1  0.922  0.165  0.194  1.0
  O  O18  1  0.165  0.078  0.806  1.0
  O  O19  1  0.422  0.335  0.806  1.0
  O  O20  1  0.835  0.922  0.806  1.0
  O  O21  1  0.578  0.665  0.806  1.0
  O  O22  1  0.335  0.578  0.194  1.0
  O  O23  1  0.665  0.422  0.194  1.0
[/CIF]
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