The crystal structure described by Sr2TiCu2AlO7 crystallizes in the monoclinic Cc space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(6) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(1), one O(5), two equivalent O(3), and three equivalent O(7) atoms. Ti(1) is bonded to one O(6), one O(7), and two equivalent O(1) atoms to form corner-sharing TiO4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(4) atoms. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(3) and two equivalent O(5) atoms. Al(1) is bonded in a distorted tetrahedral geometry to one O(2), one O(3), one O(4), and one O(5) atom. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Sr(1) and one Ti(1) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to three equivalent Sr(2) and one Ti(1) atom. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Ti(1) atoms. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), two equivalent Cu(1), and one Al(1) atom. In the fifth O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Sr(2), two equivalent Cu(2), and one Al(1) atom. In the sixth O site, O(4) is bonded to one Sr(1), two equivalent Cu(1), and one Al(1) atom to form distorted corner-sharing OSrAlCu2 trigonal pyramids. In the seventh O site, O(5) is bonded to one Sr(2), two equivalent Cu(2), and one Al(1) atom to form distorted corner-sharing OSrAlCu2 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sr2TiAlCu2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.442
_cell_length_b   5.734
_cell_length_c   12.101
_cell_angle_alpha   103.837
_cell_angle_beta   103.064
_cell_angle_gamma   89.926
_symmetry_Int_Tables_number   1
_cell_volume   356.621
_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  0.367  0.332  0.720  1.0
  Sr  Sr1  1  0.646  0.673  0.281  1.0
  Sr  Sr2  1  0.867  0.892  0.720  1.0
  Sr  Sr3  1  0.146  0.110  0.280  1.0
  Ti  Ti4  1  0.285  0.677  0.500  1.0
  Ti  Ti5  1  0.785  0.326  0.500  1.0
  Al  Al6  1  0.976  0.999  0.000  1.0
  Al  Al7  1  0.477  0.504  0.000  1.0
  Cu  Cu8  1  0.427  0.941  0.890  1.0
  Cu  Cu9  1  0.536  0.066  0.111  1.0
  Cu  Cu10  1  0.928  0.453  0.890  1.0
  Cu  Cu11  1  0.037  0.547  0.111  1.0
  O  O12  1  0.130  0.381  0.500  1.0
  O  O13  1  0.631  0.622  0.500  1.0
  O  O14  1  0.244  0.282  0.891  1.0
  O  O15  1  0.349  0.721  0.111  1.0
  O  O16  1  0.744  0.112  0.891  1.0
  O  O17  1  0.848  0.892  0.110  1.0
  O  O18  1  0.605  0.612  0.892  1.0
  O  O19  1  0.712  0.394  0.109  1.0
  O  O20  1  0.106  0.783  0.892  1.0
  O  O21  1  0.212  0.218  0.109  1.0
  O  O22  1  0.273  0.883  0.635  1.0
  O  O23  1  0.638  0.121  0.366  1.0
  O  O24  1  0.773  0.256  0.635  1.0
  O  O25  1  0.138  0.747  0.366  1.0
[/CIF]
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The crystal structure described by Sr2TiCu2AlO7 crystallizes in the monoclinic Cc space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(4), and two equivalent O(6) atoms. In the second Sr site, Sr(2) is bonded in a 7-coordinate geometry to one O(1), one O(5), two equivalent O(3), and three equivalent O(7) atoms. Ti(1) is bonded to one O(6), one O(7), and two equivalent O(1) atoms to form corner-sharing TiO4 tetrahedra. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded in a rectangular see-saw-like geometry to two equivalent O(2) and two equivalent O(4) atoms. In the second Cu site, Cu(2) is bonded in a rectangular see-saw-like geometry to two equivalent O(3) and two equivalent O(5) atoms. Al(1) is bonded in a distorted tetrahedral geometry to one O(2), one O(3), one O(4), and one O(5) atom. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Sr(1) and one Ti(1) atom. In the second O site, O(7) is bonded in a 3-coordinate geometry to three equivalent Sr(2) and one Ti(1) atom. In the third O site, O(1) is bonded in a 4-coordinate geometry to one Sr(1), one Sr(2), and two equivalent Ti(1) atoms. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to one Sr(1), two equivalent Cu(1), and one Al(1) atom. In the fifth O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Sr(2), two equivalent Cu(2), and one Al(1) atom. In the sixth O site, O(4) is bonded to one Sr(1), two equivalent Cu(1), and one Al(1) atom to form distorted corner-sharing OSrAlCu2 trigonal pyramids. In the seventh O site, O(5) is bonded to one Sr(2), two equivalent Cu(2), and one Al(1) atom to form distorted corner-sharing OSrAlCu2 trigonal pyramids. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sr2TiAlCu2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.442
_cell_length_b   5.734
_cell_length_c   12.101
_cell_angle_alpha   103.837
_cell_angle_beta   103.064
_cell_angle_gamma   89.926
_symmetry_Int_Tables_number   1
_cell_volume   356.621
_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  0.367  0.332  0.720  1.0
  Sr  Sr1  1  0.646  0.673  0.281  1.0
  Sr  Sr2  1  0.867  0.892  0.720  1.0
  Sr  Sr3  1  0.146  0.110  0.280  1.0
  Ti  Ti4  1  0.285  0.677  0.500  1.0
  Ti  Ti5  1  0.785  0.326  0.500  1.0
  Al  Al6  1  0.976  0.999  0.000  1.0
  Al  Al7  1  0.477  0.504  0.000  1.0
  Cu  Cu8  1  0.427  0.941  0.890  1.0
  Cu  Cu9  1  0.536  0.066  0.111  1.0
  Cu  Cu10  1  0.928  0.453  0.890  1.0
  Cu  Cu11  1  0.037  0.547  0.111  1.0
  O  O12  1  0.130  0.381  0.500  1.0
  O  O13  1  0.631  0.622  0.500  1.0
  O  O14  1  0.244  0.282  0.891  1.0
  O  O15  1  0.349  0.721  0.111  1.0
  O  O16  1  0.744  0.112  0.891  1.0
  O  O17  1  0.848  0.892  0.110  1.0
  O  O18  1  0.605  0.612  0.892  1.0
  O  O19  1  0.712  0.394  0.109  1.0
  O  O20  1  0.106  0.783  0.892  1.0
  O  O21  1  0.212  0.218  0.109  1.0
  O  O22  1  0.273  0.883  0.635  1.0
  O  O23  1  0.638  0.121  0.366  1.0
  O  O24  1  0.773  0.256  0.635  1.0
  O  O25  1  0.138  0.747  0.366  1.0
[/CIF]
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