The compound described by CaAl2(SiO5)2 crystallizes in the monoclinic P2_1/m space group. Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(2), and two equivalent O(3) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Al(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-62°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ca(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Ca(1) atom. is represented by the CIF card [CIF]
data_CaAl2(SiO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.301
_cell_length_b   5.362
_cell_length_c   13.015
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   113.308
_symmetry_Int_Tables_number   1
_cell_volume   339.761
_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  0.343  0.659  0.250  1.0
  Ca  Ca1  1  0.657  0.341  0.750  1.0
  Al  Al2  1  0.000  0.500  0.500  1.0
  Al  Al3  1  0.000  0.500  0.000  1.0
  Al  Al4  1  0.500  0.000  0.500  1.0
  Al  Al5  1  0.500  0.000  0.000  1.0
  Si  Si6  1  0.007  0.969  0.630  1.0
  Si  Si7  1  0.993  0.031  0.130  1.0
  Si  Si8  1  0.993  0.031  0.370  1.0
  Si  Si9  1  0.007  0.969  0.870  1.0
  O  O10  1  0.068  0.977  0.250  1.0
  O  O11  1  0.932  0.023  0.750  1.0
  O  O12  1  0.342  0.096  0.617  1.0
  O  O13  1  0.658  0.904  0.117  1.0
  O  O14  1  0.658  0.904  0.383  1.0
  O  O15  1  0.342  0.096  0.883  1.0
  O  O16  1  0.871  0.641  0.889  1.0
  O  O17  1  0.129  0.359  0.389  1.0
  O  O18  1  0.129  0.359  0.111  1.0
  O  O19  1  0.871  0.641  0.611  1.0
  O  O20  1  0.858  0.137  0.566  1.0
  O  O21  1  0.142  0.863  0.066  1.0
  O  O22  1  0.142  0.863  0.434  1.0
  O  O23  1  0.858  0.137  0.934  1.0
  O  O24  1  0.350  0.652  0.563  1.0
  O  O25  1  0.650  0.348  0.063  1.0
  O  O26  1  0.650  0.348  0.437  1.0
  O  O27  1  0.350  0.652  0.937  1.0
  O  O28  1  0.703  0.470  0.250  1.0
  O  O29  1  0.297  0.530  0.750  1.0
[/CIF]
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The compound described by CaAl2(SiO5)2 crystallizes in the monoclinic P2_1/m space group. Ca(1) is bonded in a 6-coordinate geometry to one O(1), one O(6), two equivalent O(2), and two equivalent O(3) atoms. There are two inequivalent Al sites. In the first Al site, Al(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Al(2)O6 octahedra. In the second Al site, Al(2) is bonded to two equivalent O(2), two equivalent O(4), and two equivalent O(5) atoms to form AlO6 octahedra that share corners with four equivalent Si(1)O4 tetrahedra and edges with two equivalent Al(1)O6 octahedra. Si(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O6 octahedra, corners with two equivalent Al(2)O6 octahedra, and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 47-62°. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1) and two equivalent Si(1) atoms. In the second O site, O(2) is bonded in a trigonal planar geometry to one Ca(1), one Al(2), and one Si(1) atom. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ca(1), one Al(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Al(1), one Al(2), and one Si(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Al(1) and one Al(2) atom. In the sixth O site, O(6) is bonded in a single-bond geometry to one Ca(1) atom. is represented by the CIF card [CIF]
data_CaAl2(SiO5)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.301
_cell_length_b   5.362
_cell_length_c   13.015
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   113.308
_symmetry_Int_Tables_number   1
_cell_volume   339.761
_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  0.343  0.659  0.250  1.0
  Ca  Ca1  1  0.657  0.341  0.750  1.0
  Al  Al2  1  0.000  0.500  0.500  1.0
  Al  Al3  1  0.000  0.500  0.000  1.0
  Al  Al4  1  0.500  0.000  0.500  1.0
  Al  Al5  1  0.500  0.000  0.000  1.0
  Si  Si6  1  0.007  0.969  0.630  1.0
  Si  Si7  1  0.993  0.031  0.130  1.0
  Si  Si8  1  0.993  0.031  0.370  1.0
  Si  Si9  1  0.007  0.969  0.870  1.0
  O  O10  1  0.068  0.977  0.250  1.0
  O  O11  1  0.932  0.023  0.750  1.0
  O  O12  1  0.342  0.096  0.617  1.0
  O  O13  1  0.658  0.904  0.117  1.0
  O  O14  1  0.658  0.904  0.383  1.0
  O  O15  1  0.342  0.096  0.883  1.0
  O  O16  1  0.871  0.641  0.889  1.0
  O  O17  1  0.129  0.359  0.389  1.0
  O  O18  1  0.129  0.359  0.111  1.0
  O  O19  1  0.871  0.641  0.611  1.0
  O  O20  1  0.858  0.137  0.566  1.0
  O  O21  1  0.142  0.863  0.066  1.0
  O  O22  1  0.142  0.863  0.434  1.0
  O  O23  1  0.858  0.137  0.934  1.0
  O  O24  1  0.350  0.652  0.563  1.0
  O  O25  1  0.650  0.348  0.063  1.0
  O  O26  1  0.650  0.348  0.437  1.0
  O  O27  1  0.350  0.652  0.937  1.0
  O  O28  1  0.703  0.470  0.250  1.0
  O  O29  1  0.297  0.530  0.750  1.0
[/CIF]
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