The material structure described by CaAl4(SiO6)2 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with six equivalent Al(2)O4 tetrahedra and corners with six equivalent Si(1)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form distorted AlO6 octahedra that share corners with two equivalent Al(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and edges with three equivalent Al(1)O6 octahedra. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and corners with three equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-66°. Si(1) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and corners with three equivalent Al(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-61°. There are six inequivalent O sites. In the first O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Al(1) and one O(2) atom. In the second O site, O(3) is bonded in a distorted trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the third O site, O(4) is bonded in a trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the fourth O site, O(5) is bonded in a trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the fifth O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_CaAl4(SiO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.197
_cell_length_b   5.224
_cell_length_c   19.372
_cell_angle_alpha   87.895
_cell_angle_beta   85.765
_cell_angle_gamma   60.172
_symmetry_Int_Tables_number   1
_cell_volume   455.091
_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
  Ca  Ca0  1  0.907  0.185  0.250  1.0
  Ca  Ca1  1  0.093  0.815  0.750  1.0
  Al  Al2  1  0.178  0.195  0.501  1.0
  Al  Al3  1  0.627  0.195  0.999  1.0
  Al  Al4  1  0.822  0.805  0.499  1.0
  Al  Al5  1  0.373  0.805  0.001  1.0
  Al  Al6  1  0.201  0.514  0.357  1.0
  Al  Al7  1  0.284  0.514  0.143  1.0
  Al  Al8  1  0.799  0.486  0.643  1.0
  Al  Al9  1  0.716  0.486  0.857  1.0
  Si  Si10  1  0.541  0.858  0.356  1.0
  Si  Si11  1  0.601  0.858  0.144  1.0
  Si  Si12  1  0.459  0.142  0.644  1.0
  Si  Si13  1  0.399  0.142  0.856  1.0
  O  O14  1  0.501  0.579  0.331  1.0
  O  O15  1  0.920  0.579  0.169  1.0
  O  O16  1  0.499  0.421  0.669  1.0
  O  O17  1  0.080  0.421  0.831  1.0
  O  O18  1  0.925  0.081  0.466  1.0
  O  O19  1  0.994  0.081  0.034  1.0
  O  O20  1  0.075  0.919  0.534  1.0
  O  O21  1  0.006  0.919  0.966  1.0
  O  O22  1  0.121  0.500  0.444  1.0
  O  O23  1  0.379  0.500  0.056  1.0
  O  O24  1  0.879  0.500  0.556  1.0
  O  O25  1  0.621  0.500  0.944  1.0
  O  O26  1  0.282  0.167  0.321  1.0
  O  O27  1  0.551  0.167  0.179  1.0
  O  O28  1  0.718  0.833  0.679  1.0
  O  O29  1  0.449  0.833  0.821  1.0
  O  O30  1  0.869  0.797  0.321  1.0
  O  O31  1  0.333  0.797  0.179  1.0
  O  O32  1  0.131  0.203  0.679  1.0
  O  O33  1  0.667  0.203  0.821  1.0
  O  O34  1  0.519  0.904  0.440  1.0
  O  O35  1  0.577  0.904  0.060  1.0
  O  O36  1  0.481  0.096  0.560  1.0
  O  O37  1  0.423  0.096  0.940  1.0
[/CIF]
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The material structure described by CaAl4(SiO6)2 crystallizes in the monoclinic C2/c space group. Ca(1) is bonded to two equivalent O(1), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with six equivalent Al(2)O4 tetrahedra and corners with six equivalent Si(1)O4 tetrahedra. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(6) atoms to form distorted AlO6 octahedra that share corners with two equivalent Al(2)O4 tetrahedra, corners with two equivalent Si(1)O4 tetrahedra, and edges with three equivalent Al(1)O6 octahedra. In the second Al site, Al(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form AlO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and corners with three equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 48-66°. Si(1) is bonded to one O(1), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with three equivalent Ca(1)O6 octahedra, and corners with three equivalent Al(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 50-61°. There are six inequivalent O sites. In the first O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Al(1) and one O(2) atom. In the second O site, O(3) is bonded in a distorted trigonal planar geometry to one Al(2) and two equivalent Al(1) atoms. In the third O site, O(4) is bonded in a trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the fourth O site, O(5) is bonded in a trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the fifth O site, O(6) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. In the sixth O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. is represented by the CIF file [CIF]
data_CaAl4(SiO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.197
_cell_length_b   5.224
_cell_length_c   19.372
_cell_angle_alpha   87.895
_cell_angle_beta   85.765
_cell_angle_gamma   60.172
_symmetry_Int_Tables_number   1
_cell_volume   455.091
_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
  Ca  Ca0  1  0.907  0.185  0.250  1.0
  Ca  Ca1  1  0.093  0.815  0.750  1.0
  Al  Al2  1  0.178  0.195  0.501  1.0
  Al  Al3  1  0.627  0.195  0.999  1.0
  Al  Al4  1  0.822  0.805  0.499  1.0
  Al  Al5  1  0.373  0.805  0.001  1.0
  Al  Al6  1  0.201  0.514  0.357  1.0
  Al  Al7  1  0.284  0.514  0.143  1.0
  Al  Al8  1  0.799  0.486  0.643  1.0
  Al  Al9  1  0.716  0.486  0.857  1.0
  Si  Si10  1  0.541  0.858  0.356  1.0
  Si  Si11  1  0.601  0.858  0.144  1.0
  Si  Si12  1  0.459  0.142  0.644  1.0
  Si  Si13  1  0.399  0.142  0.856  1.0
  O  O14  1  0.501  0.579  0.331  1.0
  O  O15  1  0.920  0.579  0.169  1.0
  O  O16  1  0.499  0.421  0.669  1.0
  O  O17  1  0.080  0.421  0.831  1.0
  O  O18  1  0.925  0.081  0.466  1.0
  O  O19  1  0.994  0.081  0.034  1.0
  O  O20  1  0.075  0.919  0.534  1.0
  O  O21  1  0.006  0.919  0.966  1.0
  O  O22  1  0.121  0.500  0.444  1.0
  O  O23  1  0.379  0.500  0.056  1.0
  O  O24  1  0.879  0.500  0.556  1.0
  O  O25  1  0.621  0.500  0.944  1.0
  O  O26  1  0.282  0.167  0.321  1.0
  O  O27  1  0.551  0.167  0.179  1.0
  O  O28  1  0.718  0.833  0.679  1.0
  O  O29  1  0.449  0.833  0.821  1.0
  O  O30  1  0.869  0.797  0.321  1.0
  O  O31  1  0.333  0.797  0.179  1.0
  O  O32  1  0.131  0.203  0.679  1.0
  O  O33  1  0.667  0.203  0.821  1.0
  O  O34  1  0.519  0.904  0.440  1.0
  O  O35  1  0.577  0.904  0.060  1.0
  O  O36  1  0.481  0.096  0.560  1.0
  O  O37  1  0.423  0.096  0.940  1.0
[/CIF]
.