The structure described by Sr2CaTi3O9 crystallizes in the orthorhombic Fmm2 space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(1), and four equivalent O(6) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra, faces with two equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, and faces with eight equivalent Ti(1)O6 octahedra. In the second Sr site, Sr(2) is bonded to one O(3), one O(4), two equivalent O(5), two equivalent O(6), two equivalent O(7), and four equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, corners with eight equivalent Sr(2)O12 cuboctahedra,  a faceface with one Sr(1)O12 cuboctahedra, faces with five equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. In the third Sr site, Sr(3) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(1), and four equivalent O(6) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, corners with eight equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Ti(1)O6 octahedra. Ca(1) is bonded to one O(3), one O(4), two equivalent O(5), two equivalent O(6), two equivalent O(7), and four equivalent O(2) atoms to form CaO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra,  a faceface with one Sr(3)O12 cuboctahedra, faces with five equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(6) atoms to form TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with five equivalent Ti(1)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Sr(3)O12 cuboctahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. In the second Ti site, Ti(2) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Ca(1), and two equivalent Ti(2) atoms. In the second O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), and two equivalent Ti(1) atoms. In the third O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Ca(1), one Ti(1), and one Ti(2) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Ca(1), and two equivalent Ti(1) atoms. In the fifth O site, O(4) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Ca(1), and two equivalent Ti(1) atoms. In the sixth O site, O(6) is bonded in a distorted linear geometry to one Sr(1), one Sr(2), one Sr(3), one Ca(1), and two equivalent Ti(1) atoms. In the seventh O site, O(7) is bonded in a distorted linear geometry to two equivalent Sr(2), two equivalent Ca(1), and two equivalent Ti(2) atoms. is represented by the CIF card [CIF]
data_Sr2CaTi3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.397
_cell_length_b   12.390
_cell_length_c   5.557
_cell_angle_alpha   77.116
_cell_angle_beta   76.974
_cell_angle_gamma   25.911
_symmetry_Int_Tables_number   1
_cell_volume   362.959
_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
  Sr  Sr0  1  0.750  0.250  0.750  1.0
  Sr  Sr1  1  0.583  0.083  0.917  1.0
  Sr  Sr2  1  0.917  0.417  0.583  1.0
  Sr  Sr3  1  0.250  0.750  0.250  1.0
  Ca  Ca4  1  0.083  0.583  0.417  1.0
  Ca  Ca5  1  0.417  0.917  0.083  1.0
  Ti  Ti6  1  0.334  0.833  0.666  1.0
  Ti  Ti7  1  0.666  0.167  0.334  1.0
  Ti  Ti8  1  1.000  0.500  1.000  1.0
  Ti  Ti9  1  0.167  0.666  0.833  1.0
  Ti  Ti10  1  0.500  0.000  0.500  1.0
  Ti  Ti11  1  0.833  0.334  0.167  1.0
  O  O12  1  0.223  0.777  0.776  1.0
  O  O13  1  0.554  0.112  0.443  1.0
  O  O14  1  0.888  0.446  0.110  1.0
  O  O15  1  0.443  0.890  0.554  1.0
  O  O16  1  0.776  0.224  0.223  1.0
  O  O17  1  0.110  0.557  0.888  1.0
  O  O18  1  0.094  0.091  0.909  1.0
  O  O19  1  0.425  0.426  0.574  1.0
  O  O20  1  0.761  0.758  0.242  1.0
  O  O21  1  0.574  0.575  0.425  1.0
  O  O22  1  0.909  0.906  0.094  1.0
  O  O23  1  0.242  0.239  0.761  1.0
  O  O24  1  0.416  0.417  0.084  1.0
  O  O25  1  0.750  0.750  0.750  1.0
  O  O26  1  0.084  0.083  0.416  1.0
  O  O27  1  0.250  0.250  0.250  1.0
  O  O28  1  0.583  0.584  0.917  1.0
  O  O29  1  0.917  0.916  0.583  1.0
[/CIF]
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The structure described by Sr2CaTi3O9 crystallizes in the orthorhombic Fmm2 space group. There are three inequivalent Sr sites. In the first Sr site, Sr(1) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(1), and four equivalent O(6) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra, faces with two equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Sr(3)O12 cuboctahedra, and faces with eight equivalent Ti(1)O6 octahedra. In the second Sr site, Sr(2) is bonded to one O(3), one O(4), two equivalent O(5), two equivalent O(6), two equivalent O(7), and four equivalent O(2) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, corners with eight equivalent Sr(2)O12 cuboctahedra,  a faceface with one Sr(1)O12 cuboctahedra, faces with five equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. In the third Sr site, Sr(3) is bonded to two equivalent O(3), two equivalent O(4), four equivalent O(1), and four equivalent O(6) atoms to form SrO12 cuboctahedra that share corners with four equivalent Sr(3)O12 cuboctahedra, corners with eight equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Sr(1)O12 cuboctahedra, and faces with eight equivalent Ti(1)O6 octahedra. Ca(1) is bonded to one O(3), one O(4), two equivalent O(5), two equivalent O(6), two equivalent O(7), and four equivalent O(2) atoms to form CaO12 cuboctahedra that share corners with four equivalent Sr(1)O12 cuboctahedra, corners with eight equivalent Ca(1)O12 cuboctahedra,  a faceface with one Sr(3)O12 cuboctahedra, faces with five equivalent Sr(2)O12 cuboctahedra, faces with four equivalent Ti(1)O6 octahedra, and faces with four equivalent Ti(2)O6 octahedra. There are two inequivalent Ti sites. In the first Ti site, Ti(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(6) atoms to form TiO6 octahedra that share  a cornercorner with one Ti(2)O6 octahedra, corners with five equivalent Ti(1)O6 octahedra, faces with two equivalent Sr(1)O12 cuboctahedra, faces with two equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Sr(3)O12 cuboctahedra, and faces with two equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. In the second Ti site, Ti(2) is bonded to two equivalent O(2), two equivalent O(5), and two equivalent O(7) atoms to form TiO6 octahedra that share corners with two equivalent Ti(1)O6 octahedra, corners with four equivalent Ti(2)O6 octahedra, faces with four equivalent Sr(2)O12 cuboctahedra, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are seven inequivalent O sites. In the first O site, O(5) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Ca(1), and two equivalent Ti(2) atoms. In the second O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Sr(1), two equivalent Sr(3), and two equivalent Ti(1) atoms. In the third O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Ca(1), one Ti(1), and one Ti(2) atom. In the fourth O site, O(3) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Ca(1), and two equivalent Ti(1) atoms. In the fifth O site, O(4) is bonded in a 2-coordinate geometry to one Sr(1), one Sr(2), one Sr(3), one Ca(1), and two equivalent Ti(1) atoms. In the sixth O site, O(6) is bonded in a distorted linear geometry to one Sr(1), one Sr(2), one Sr(3), one Ca(1), and two equivalent Ti(1) atoms. In the seventh O site, O(7) is bonded in a distorted linear geometry to two equivalent Sr(2), two equivalent Ca(1), and two equivalent Ti(2) atoms. is represented by the CIF card [CIF]
data_Sr2CaTi3O9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   12.397
_cell_length_b   12.390
_cell_length_c   5.557
_cell_angle_alpha   77.116
_cell_angle_beta   76.974
_cell_angle_gamma   25.911
_symmetry_Int_Tables_number   1
_cell_volume   362.959
_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
  Sr  Sr0  1  0.750  0.250  0.750  1.0
  Sr  Sr1  1  0.583  0.083  0.917  1.0
  Sr  Sr2  1  0.917  0.417  0.583  1.0
  Sr  Sr3  1  0.250  0.750  0.250  1.0
  Ca  Ca4  1  0.083  0.583  0.417  1.0
  Ca  Ca5  1  0.417  0.917  0.083  1.0
  Ti  Ti6  1  0.334  0.833  0.666  1.0
  Ti  Ti7  1  0.666  0.167  0.334  1.0
  Ti  Ti8  1  1.000  0.500  1.000  1.0
  Ti  Ti9  1  0.167  0.666  0.833  1.0
  Ti  Ti10  1  0.500  0.000  0.500  1.0
  Ti  Ti11  1  0.833  0.334  0.167  1.0
  O  O12  1  0.223  0.777  0.776  1.0
  O  O13  1  0.554  0.112  0.443  1.0
  O  O14  1  0.888  0.446  0.110  1.0
  O  O15  1  0.443  0.890  0.554  1.0
  O  O16  1  0.776  0.224  0.223  1.0
  O  O17  1  0.110  0.557  0.888  1.0
  O  O18  1  0.094  0.091  0.909  1.0
  O  O19  1  0.425  0.426  0.574  1.0
  O  O20  1  0.761  0.758  0.242  1.0
  O  O21  1  0.574  0.575  0.425  1.0
  O  O22  1  0.909  0.906  0.094  1.0
  O  O23  1  0.242  0.239  0.761  1.0
  O  O24  1  0.416  0.417  0.084  1.0
  O  O25  1  0.750  0.750  0.750  1.0
  O  O26  1  0.084  0.083  0.416  1.0
  O  O27  1  0.250  0.250  0.250  1.0
  O  O28  1  0.583  0.584  0.917  1.0
  O  O29  1  0.917  0.916  0.583  1.0
[/CIF]
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