The structure described by CaAl2(SiO5)2 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded to one O(1), one O(5), and four equivalent O(2) atoms to form CaO6 octahedra that share corners with four equivalent Al(1)O6 octahedra and corners with six equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. Al(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form AlO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 58°. Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra, corners with four equivalent Al(1)O6 octahedra, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-66°. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Al(1) and one O(4) atom. In the second O site, O(5) is bonded in a single-bond geometry to one Ca(1) atom. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Si(1) atoms. In the fourth O site, O(2) is bonded in a trigonal planar geometry to one Ca(1), one Al(1), and one Si(1) atom. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. is represented by the CIF card [CIF]
data_CaAl2(SiO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.041
_cell_length_b   5.041
_cell_length_c   13.268
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   104.345
_symmetry_Int_Tables_number   1
_cell_volume   326.630
_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  0.355  0.645  0.250  1.0
  Ca  Ca1  1  0.645  0.355  0.750  1.0
  Al  Al2  1  0.000  0.500  0.500  1.0
  Al  Al3  1  0.500  0.000  0.500  1.0
  Al  Al4  1  0.000  0.500  0.000  1.0
  Al  Al5  1  0.500  0.000  0.000  1.0
  Si  Si6  1  0.969  0.031  0.365  1.0
  Si  Si7  1  0.031  0.969  0.635  1.0
  Si  Si8  1  0.969  0.031  0.135  1.0
  Si  Si9  1  0.031  0.969  0.865  1.0
  O  O10  1  0.054  0.946  0.250  1.0
  O  O11  1  0.946  0.054  0.750  1.0
  O  O12  1  0.073  0.360  0.379  1.0
  O  O13  1  0.360  0.073  0.621  1.0
  O  O14  1  0.073  0.360  0.121  1.0
  O  O15  1  0.360  0.073  0.879  1.0
  O  O16  1  0.927  0.640  0.621  1.0
  O  O17  1  0.640  0.927  0.379  1.0
  O  O18  1  0.927  0.640  0.879  1.0
  O  O19  1  0.640  0.927  0.121  1.0
  O  O20  1  0.135  0.865  0.441  1.0
  O  O21  1  0.865  0.135  0.559  1.0
  O  O22  1  0.135  0.865  0.059  1.0
  O  O23  1  0.865  0.135  0.941  1.0
  O  O24  1  0.579  0.421  0.472  1.0
  O  O25  1  0.421  0.579  0.528  1.0
  O  O26  1  0.579  0.421  0.028  1.0
  O  O27  1  0.421  0.579  0.972  1.0
  O  O28  1  0.651  0.349  0.250  1.0
  O  O29  1  0.349  0.651  0.750  1.0
[/CIF]
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The structure described by CaAl2(SiO5)2 crystallizes in the orthorhombic Cmcm space group. Ca(1) is bonded to one O(1), one O(5), and four equivalent O(2) atoms to form CaO6 octahedra that share corners with four equivalent Al(1)O6 octahedra and corners with six equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 58°. Al(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form AlO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with four equivalent Si(1)O4 tetrahedra, and edges with two equivalent Al(1)O6 octahedra. The corner-sharing octahedral tilt angles are 58°. Si(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form SiO4 tetrahedra that share corners with three equivalent Ca(1)O6 octahedra, corners with four equivalent Al(1)O6 octahedra, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-66°. There are five inequivalent O sites. In the first O site, O(4) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Al(1) and one O(4) atom. In the second O site, O(5) is bonded in a single-bond geometry to one Ca(1) atom. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to one Ca(1) and two equivalent Si(1) atoms. In the fourth O site, O(2) is bonded in a trigonal planar geometry to one Ca(1), one Al(1), and one Si(1) atom. In the fifth O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Al(1) and one Si(1) atom. is represented by the CIF card [CIF]
data_CaAl2(SiO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.041
_cell_length_b   5.041
_cell_length_c   13.268
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   104.345
_symmetry_Int_Tables_number   1
_cell_volume   326.630
_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  0.355  0.645  0.250  1.0
  Ca  Ca1  1  0.645  0.355  0.750  1.0
  Al  Al2  1  0.000  0.500  0.500  1.0
  Al  Al3  1  0.500  0.000  0.500  1.0
  Al  Al4  1  0.000  0.500  0.000  1.0
  Al  Al5  1  0.500  0.000  0.000  1.0
  Si  Si6  1  0.969  0.031  0.365  1.0
  Si  Si7  1  0.031  0.969  0.635  1.0
  Si  Si8  1  0.969  0.031  0.135  1.0
  Si  Si9  1  0.031  0.969  0.865  1.0
  O  O10  1  0.054  0.946  0.250  1.0
  O  O11  1  0.946  0.054  0.750  1.0
  O  O12  1  0.073  0.360  0.379  1.0
  O  O13  1  0.360  0.073  0.621  1.0
  O  O14  1  0.073  0.360  0.121  1.0
  O  O15  1  0.360  0.073  0.879  1.0
  O  O16  1  0.927  0.640  0.621  1.0
  O  O17  1  0.640  0.927  0.379  1.0
  O  O18  1  0.927  0.640  0.879  1.0
  O  O19  1  0.640  0.927  0.121  1.0
  O  O20  1  0.135  0.865  0.441  1.0
  O  O21  1  0.865  0.135  0.559  1.0
  O  O22  1  0.135  0.865  0.059  1.0
  O  O23  1  0.865  0.135  0.941  1.0
  O  O24  1  0.579  0.421  0.472  1.0
  O  O25  1  0.421  0.579  0.528  1.0
  O  O26  1  0.579  0.421  0.028  1.0
  O  O27  1  0.421  0.579  0.972  1.0
  O  O28  1  0.651  0.349  0.250  1.0
  O  O29  1  0.349  0.651  0.750  1.0
[/CIF]
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