The crystal structure described by Sr3Ta6(Si2O13)2 crystallizes in the hexagonal P-62m space group. Sr(1) is bonded in a 12-coordinate geometry to two equivalent O(1), two equivalent O(5), and eight equivalent O(2) atoms. Ta(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 9-36°. Si(1) is bonded to one O(3) and three equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Ta(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Sr(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Sr(1), one Ta(1), and one Si(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Sr(1) and two equivalent Ta(1) atoms. is represented by the CIF file [CIF]
data_Sr3Ta6(Si2O13)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.035
_cell_length_b   9.035
_cell_length_c   7.742
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   547.317
_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
  Sr  Sr0  1  0.403  0.403  0.500  1.0
  Sr  Sr1  1  0.000  0.597  0.500  1.0
  Sr  Sr2  1  0.597  0.000  0.500  1.0
  Ta  Ta3  1  0.000  0.239  0.754  1.0
  Ta  Ta4  1  0.761  0.761  0.754  1.0
  Ta  Ta5  1  0.239  0.000  0.246  1.0
  Ta  Ta6  1  0.761  0.761  0.246  1.0
  Ta  Ta7  1  0.239  0.000  0.754  1.0
  Ta  Ta8  1  0.000  0.239  0.246  1.0
  Si  Si9  1  0.667  0.333  0.209  1.0
  Si  Si10  1  0.667  0.333  0.791  1.0
  Si  Si11  1  0.333  0.667  0.791  1.0
  Si  Si12  1  0.333  0.667  0.209  1.0
  O  O13  1  0.000  0.221  0.500  1.0
  O  O14  1  0.779  0.779  0.500  1.0
  O  O15  1  0.221  0.000  0.500  1.0
  O  O16  1  0.509  0.686  0.291  1.0
  O  O17  1  0.314  0.823  0.291  1.0
  O  O18  1  0.177  0.491  0.291  1.0
  O  O19  1  0.491  0.177  0.709  1.0
  O  O20  1  0.177  0.491  0.709  1.0
  O  O21  1  0.509  0.686  0.709  1.0
  O  O22  1  0.314  0.823  0.709  1.0
  O  O23  1  0.686  0.509  0.291  1.0
  O  O24  1  0.823  0.314  0.291  1.0
  O  O25  1  0.823  0.314  0.709  1.0
  O  O26  1  0.333  0.667  0.000  1.0
  O  O27  1  0.667  0.333  0.000  1.0
  O  O28  1  0.279  0.000  0.000  1.0
  O  O29  1  0.721  0.721  0.000  1.0
  O  O30  1  0.000  0.279  0.000  1.0
  O  O31  1  0.815  0.000  0.235  1.0
  O  O32  1  0.185  0.185  0.765  1.0
  O  O33  1  0.000  0.815  0.765  1.0
  O  O34  1  0.000  0.815  0.235  1.0
  O  O35  1  0.185  0.185  0.235  1.0
  O  O36  1  0.815  0.000  0.765  1.0
  O  O37  1  0.491  0.177  0.291  1.0
  O  O38  1  0.686  0.509  0.709  1.0
[/CIF]
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The crystal structure described by Sr3Ta6(Si2O13)2 crystallizes in the hexagonal P-62m space group. Sr(1) is bonded in a 12-coordinate geometry to two equivalent O(1), two equivalent O(5), and eight equivalent O(2) atoms. Ta(1) is bonded to one O(1), one O(4), two equivalent O(2), and two equivalent O(5) atoms to form TaO6 octahedra that share corners with four equivalent Ta(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 9-36°. Si(1) is bonded to one O(3) and three equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Ta(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 34°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent Sr(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Sr(1), one Ta(1), and one Si(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent Si(1) atoms. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to two equivalent Ta(1) atoms. In the fifth O site, O(5) is bonded in a distorted bent 150 degrees geometry to one Sr(1) and two equivalent Ta(1) atoms. is represented by the CIF file [CIF]
data_Sr3Ta6(Si2O13)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.035
_cell_length_b   9.035
_cell_length_c   7.742
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   547.317
_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
  Sr  Sr0  1  0.403  0.403  0.500  1.0
  Sr  Sr1  1  0.000  0.597  0.500  1.0
  Sr  Sr2  1  0.597  0.000  0.500  1.0
  Ta  Ta3  1  0.000  0.239  0.754  1.0
  Ta  Ta4  1  0.761  0.761  0.754  1.0
  Ta  Ta5  1  0.239  0.000  0.246  1.0
  Ta  Ta6  1  0.761  0.761  0.246  1.0
  Ta  Ta7  1  0.239  0.000  0.754  1.0
  Ta  Ta8  1  0.000  0.239  0.246  1.0
  Si  Si9  1  0.667  0.333  0.209  1.0
  Si  Si10  1  0.667  0.333  0.791  1.0
  Si  Si11  1  0.333  0.667  0.791  1.0
  Si  Si12  1  0.333  0.667  0.209  1.0
  O  O13  1  0.000  0.221  0.500  1.0
  O  O14  1  0.779  0.779  0.500  1.0
  O  O15  1  0.221  0.000  0.500  1.0
  O  O16  1  0.509  0.686  0.291  1.0
  O  O17  1  0.314  0.823  0.291  1.0
  O  O18  1  0.177  0.491  0.291  1.0
  O  O19  1  0.491  0.177  0.709  1.0
  O  O20  1  0.177  0.491  0.709  1.0
  O  O21  1  0.509  0.686  0.709  1.0
  O  O22  1  0.314  0.823  0.709  1.0
  O  O23  1  0.686  0.509  0.291  1.0
  O  O24  1  0.823  0.314  0.291  1.0
  O  O25  1  0.823  0.314  0.709  1.0
  O  O26  1  0.333  0.667  0.000  1.0
  O  O27  1  0.667  0.333  0.000  1.0
  O  O28  1  0.279  0.000  0.000  1.0
  O  O29  1  0.721  0.721  0.000  1.0
  O  O30  1  0.000  0.279  0.000  1.0
  O  O31  1  0.815  0.000  0.235  1.0
  O  O32  1  0.185  0.185  0.765  1.0
  O  O33  1  0.000  0.815  0.765  1.0
  O  O34  1  0.000  0.815  0.235  1.0
  O  O35  1  0.185  0.185  0.235  1.0
  O  O36  1  0.815  0.000  0.765  1.0
  O  O37  1  0.491  0.177  0.291  1.0
  O  O38  1  0.686  0.509  0.709  1.0
[/CIF]
.