The crystal structure described by Ca2TiAlSi2O9F crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), and one F(1) atom. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(8), and one O(9) atom. Ti(1) is bonded to one O(2), one O(4), one O(5), one O(7), one O(9), and one F(1) atom to form TiO5F octahedra that share corners with two equivalent Al(1)O5F octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. Al(1) is bonded to one O(1), one O(3), one O(6), one O(8), one O(9), and one F(1) atom to form AlO5F octahedra that share corners with two equivalent Ti(1)O5F octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(5), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O5F octahedra and corners with two equivalent Al(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 38-56°. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O5F octahedra and corners with two equivalent Al(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 30-51°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ca(2), one Ti(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(1), one Ti(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ca(2), one Al(1), and one Si(1) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ca(2), one Ti(1), and one Al(1) atom. F(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ti(1), and one Al(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca2TiAlSi2O9F
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.425
_cell_length_b   5.470
_cell_length_c   7.149
_cell_angle_alpha   104.890
_cell_angle_beta   104.393
_cell_angle_gamma   105.621
_symmetry_Int_Tables_number   1
_cell_volume   185.584
_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
  Ca  Ca0  1  0.171  0.840  0.756  1.0
  Ca  Ca1  1  0.829  0.161  0.244  1.0
  Ti  Ti2  1  0.506  0.493  0.478  1.0
  Al  Al3  1  0.501  0.499  0.004  1.0
  Si  Si4  1  0.178  0.810  0.245  1.0
  Si  Si5  1  0.820  0.191  0.757  1.0
  O  O6  1  0.606  0.197  0.885  1.0
  O  O7  1  0.188  0.610  0.385  1.0
  O  O8  1  0.390  0.804  0.115  1.0
  O  O9  1  0.814  0.393  0.619  1.0
  O  O10  1  0.253  0.120  0.408  1.0
  O  O11  1  0.130  0.259  0.908  1.0
  O  O12  1  0.744  0.879  0.599  1.0
  O  O13  1  0.870  0.741  0.090  1.0
  O  O14  1  0.570  0.429  0.247  1.0
  F  F15  1  0.430  0.572  0.762  1.0
[/CIF]
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The crystal structure described by Ca2TiAlSi2O9F crystallizes in the triclinic P1 space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(6), one O(7), and one F(1) atom. In the second Ca site, Ca(2) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(8), and one O(9) atom. Ti(1) is bonded to one O(2), one O(4), one O(5), one O(7), one O(9), and one F(1) atom to form TiO5F octahedra that share corners with two equivalent Al(1)O5F octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. Al(1) is bonded to one O(1), one O(3), one O(6), one O(8), one O(9), and one F(1) atom to form AlO5F octahedra that share corners with two equivalent Ti(1)O5F octahedra, corners with two equivalent Si(1)O4 tetrahedra, and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(2), one O(3), one O(5), and one O(8) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O5F octahedra and corners with two equivalent Al(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 38-56°. In the second Si site, Si(2) is bonded to one O(1), one O(4), one O(6), and one O(7) atom to form SiO4 tetrahedra that share corners with two equivalent Ti(1)O5F octahedra and corners with two equivalent Al(1)O5F octahedra. The corner-sharing octahedral tilt angles range from 30-51°. There are nine inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(1), and one Si(2) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Ca(1), one Ca(2), one Ti(1), and one Si(2) atom. In the fifth O site, O(5) is bonded in a distorted T-shaped geometry to one Ca(2), one Ti(1), and one Si(1) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Ca(1), one Al(1), and one Si(2) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ca(1), one Ti(1), and one Si(2) atom. In the eighth O site, O(8) is bonded in a distorted T-shaped geometry to one Ca(2), one Al(1), and one Si(1) atom. In the ninth O site, O(9) is bonded in a 3-coordinate geometry to one Ca(2), one Ti(1), and one Al(1) atom. F(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Ti(1), and one Al(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca2TiAlSi2O9F
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.425
_cell_length_b   5.470
_cell_length_c   7.149
_cell_angle_alpha   104.890
_cell_angle_beta   104.393
_cell_angle_gamma   105.621
_symmetry_Int_Tables_number   1
_cell_volume   185.584
_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
  Ca  Ca0  1  0.171  0.840  0.756  1.0
  Ca  Ca1  1  0.829  0.161  0.244  1.0
  Ti  Ti2  1  0.506  0.493  0.478  1.0
  Al  Al3  1  0.501  0.499  0.004  1.0
  Si  Si4  1  0.178  0.810  0.245  1.0
  Si  Si5  1  0.820  0.191  0.757  1.0
  O  O6  1  0.606  0.197  0.885  1.0
  O  O7  1  0.188  0.610  0.385  1.0
  O  O8  1  0.390  0.804  0.115  1.0
  O  O9  1  0.814  0.393  0.619  1.0
  O  O10  1  0.253  0.120  0.408  1.0
  O  O11  1  0.130  0.259  0.908  1.0
  O  O12  1  0.744  0.879  0.599  1.0
  O  O13  1  0.870  0.741  0.090  1.0
  O  O14  1  0.570  0.429  0.247  1.0
  F  F15  1  0.430  0.572  0.762  1.0
[/CIF]
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