The compound described by Ba3SrMg2(Si2O7)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(1), one O(5), two equivalent O(4), two equivalent O(8), and two equivalent O(9) atoms. Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms. Mg(1) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form MgO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra and corners with two equivalent Mg(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Mg(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(2), one O(5), and two equivalent O(8) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with two equivalent Mg(1)O4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ba(2), one Sr(1), and two equivalent Si(2) atoms. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1), one Si(1), and one Si(3) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Sr(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Sr(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(1), one Mg(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Sr(1), one Mg(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba3SrMg2(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.263
_cell_length_b   8.263
_cell_length_c   5.417
_cell_angle_alpha   89.656
_cell_angle_beta   89.656
_cell_angle_gamma   90.903
_symmetry_Int_Tables_number   1
_cell_volume   369.800
_cell_formula_units_Z   1
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
  Ba  Ba0  1  0.166  0.834  0.490  1.0
  Ba  Ba1  1  0.663  0.663  0.512  1.0
  Ba  Ba2  1  0.834  0.166  0.490  1.0
  Sr  Sr3  1  0.332  0.332  0.509  1.0
  Mg  Mg4  1  0.499  0.002  0.997  1.0
  Mg  Mg5  1  0.002  0.499  0.997  1.0
  Si  Si6  1  0.144  0.144  0.950  1.0
  Si  Si7  1  0.361  0.631  0.048  1.0
  Si  Si8  1  0.864  0.864  0.955  1.0
  Si  Si9  1  0.631  0.361  0.048  1.0
  O  O10  1  0.495  0.495  0.155  1.0
  O  O11  1  0.004  0.004  0.863  1.0
  O  O12  1  0.151  0.151  0.250  1.0
  O  O13  1  0.359  0.629  0.748  1.0
  O  O14  1  0.861  0.861  0.255  1.0
  O  O15  1  0.629  0.359  0.748  1.0
  O  O16  1  0.311  0.086  0.810  1.0
  O  O17  1  0.193  0.572  0.188  1.0
  O  O18  1  0.695  0.923  0.822  1.0
  O  O19  1  0.804  0.422  0.172  1.0
  O  O20  1  0.572  0.193  0.188  1.0
  O  O21  1  0.923  0.695  0.822  1.0
  O  O22  1  0.422  0.804  0.172  1.0
  O  O23  1  0.086  0.311  0.810  1.0
[/CIF]
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The compound described by Ba3SrMg2(Si2O7)2 crystallizes in the monoclinic Cm space group. There are two inequivalent Ba sites. In the first Ba site, Ba(1) is bonded in a 8-coordinate geometry to one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), one O(8), and one O(9) atom. In the second Ba site, Ba(2) is bonded in a 8-coordinate geometry to one O(1), one O(5), two equivalent O(4), two equivalent O(8), and two equivalent O(9) atoms. Sr(1) is bonded in a 8-coordinate geometry to one O(1), one O(3), two equivalent O(4), two equivalent O(6), and two equivalent O(7) atoms. Mg(1) is bonded to one O(6), one O(7), one O(8), and one O(9) atom to form MgO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra,  a cornercorner with one Si(3)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), and two equivalent O(6) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(3)O4 tetrahedra and corners with two equivalent Mg(1)O4 tetrahedra. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(7), and one O(9) atom to form SiO4 tetrahedra that share  a cornercorner with one Si(2)O4 tetrahedra and corners with two equivalent Mg(1)O4 tetrahedra. In the third Si site, Si(3) is bonded to one O(2), one O(5), and two equivalent O(8) atoms to form SiO4 tetrahedra that share  a cornercorner with one Si(1)O4 tetrahedra and corners with two equivalent Mg(1)O4 tetrahedra. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ba(2), one Sr(1), and two equivalent Si(2) atoms. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to two equivalent Ba(1), one Si(1), and one Si(3) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Ba(1), one Sr(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Ba(1), one Ba(2), one Sr(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to one Ba(2), two equivalent Ba(1), and one Si(3) atom. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to one Ba(1), one Sr(1), one Mg(1), and one Si(1) atom. In the seventh O site, O(7) is bonded in a distorted bent 120 degrees geometry to one Ba(1), one Sr(1), one Mg(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one Si(3) atom. In the ninth O site, O(9) is bonded in a 4-coordinate geometry to one Ba(1), one Ba(2), one Mg(1), and one Si(2) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ba3SrMg2(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   8.263
_cell_length_b   8.263
_cell_length_c   5.417
_cell_angle_alpha   89.656
_cell_angle_beta   89.656
_cell_angle_gamma   90.903
_symmetry_Int_Tables_number   1
_cell_volume   369.800
_cell_formula_units_Z   1
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
  Ba  Ba0  1  0.166  0.834  0.490  1.0
  Ba  Ba1  1  0.663  0.663  0.512  1.0
  Ba  Ba2  1  0.834  0.166  0.490  1.0
  Sr  Sr3  1  0.332  0.332  0.509  1.0
  Mg  Mg4  1  0.499  0.002  0.997  1.0
  Mg  Mg5  1  0.002  0.499  0.997  1.0
  Si  Si6  1  0.144  0.144  0.950  1.0
  Si  Si7  1  0.361  0.631  0.048  1.0
  Si  Si8  1  0.864  0.864  0.955  1.0
  Si  Si9  1  0.631  0.361  0.048  1.0
  O  O10  1  0.495  0.495  0.155  1.0
  O  O11  1  0.004  0.004  0.863  1.0
  O  O12  1  0.151  0.151  0.250  1.0
  O  O13  1  0.359  0.629  0.748  1.0
  O  O14  1  0.861  0.861  0.255  1.0
  O  O15  1  0.629  0.359  0.748  1.0
  O  O16  1  0.311  0.086  0.810  1.0
  O  O17  1  0.193  0.572  0.188  1.0
  O  O18  1  0.695  0.923  0.822  1.0
  O  O19  1  0.804  0.422  0.172  1.0
  O  O20  1  0.572  0.193  0.188  1.0
  O  O21  1  0.923  0.695  0.822  1.0
  O  O22  1  0.422  0.804  0.172  1.0
  O  O23  1  0.086  0.311  0.810  1.0
[/CIF]
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