The material structure described by CaAl2Si2(O4Cl)2 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent Cl(1) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to three equivalent O(4) and three equivalent Cl(2) atoms. In the third Ca site, Ca(3) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. Al(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form AlO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(3) is bonded to one Ca(1), one Ca(3), and two equivalent Al(1) atoms to form distorted edge-sharing OCa2Al2 tetrahedra. In the third O site, O(4) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), and two equivalent Si(1) atoms. In the fourth O site, O(5) is bonded in a linear geometry to one Al(1) and one Si(1) atom. In the fifth O site, O(6) is bonded in a linear geometry to one Al(1) and one Si(1) atom. In the sixth O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Al(1) atoms. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a single-bond geometry to one Ca(1) atom. In the second Cl site, Cl(2) is bonded in a single-bond geometry to one Ca(2) atom. is represented by the CIF file [CIF]
data_CaAl2Si2(ClO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.569
_cell_length_b   9.569
_cell_length_c   9.569
_cell_angle_alpha   95.540
_cell_angle_beta   95.540
_cell_angle_gamma   95.540
_symmetry_Int_Tables_number   1
_cell_volume   862.989
_cell_formula_units_Z   3
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  0.770  0.770  0.770  1.0
  Ca  Ca1  1  0.235  0.235  0.235  1.0
  Ca  Ca2  1  0.985  0.985  0.985  1.0
  Al  Al3  1  0.668  0.106  0.887  1.0
  Al  Al4  1  0.887  0.106  0.668  1.0
  Al  Al5  1  0.106  0.887  0.668  1.0
  Al  Al6  1  0.106  0.668  0.887  1.0
  Al  Al7  1  0.887  0.668  0.106  1.0
  Al  Al8  1  0.668  0.887  0.106  1.0
  Si  Si9  1  0.324  0.899  0.111  1.0
  Si  Si10  1  0.111  0.899  0.324  1.0
  Si  Si11  1  0.899  0.111  0.324  1.0
  Si  Si12  1  0.899  0.324  0.111  1.0
  Si  Si13  1  0.111  0.324  0.899  1.0
  Si  Si14  1  0.324  0.111  0.899  1.0
  Cl  Cl15  1  0.546  0.739  0.546  1.0
  Cl  Cl16  1  0.739  0.546  0.546  1.0
  Cl  Cl17  1  0.546  0.546  0.739  1.0
  Cl  Cl18  1  0.455  0.257  0.455  1.0
  Cl  Cl19  1  0.257  0.455  0.455  1.0
  Cl  Cl20  1  0.455  0.455  0.257  1.0
  O  O21  1  0.715  0.092  0.715  1.0
  O  O22  1  0.092  0.715  0.715  1.0
  O  O23  1  0.715  0.715  0.092  1.0
  O  O24  1  0.269  0.910  0.269  1.0
  O  O25  1  0.910  0.269  0.269  1.0
  O  O26  1  0.269  0.269  0.910  1.0
  O  O27  1  0.943  0.726  0.943  1.0
  O  O28  1  0.726  0.943  0.943  1.0
  O  O29  1  0.943  0.943  0.726  1.0
  O  O30  1  0.057  0.281  0.057  1.0
  O  O31  1  0.281  0.057  0.057  1.0
  O  O32  1  0.057  0.057  0.281  1.0
  O  O33  1  0.122  0.491  0.896  1.0
  O  O34  1  0.896  0.491  0.122  1.0
  O  O35  1  0.491  0.896  0.122  1.0
  O  O36  1  0.491  0.122  0.896  1.0
  O  O37  1  0.896  0.122  0.491  1.0
  O  O38  1  0.122  0.896  0.491  1.0
  O  O39  1  0.231  0.002  0.780  1.0
  O  O40  1  0.780  0.002  0.231  1.0
  O  O41  1  0.002  0.780  0.231  1.0
  O  O42  1  0.002  0.231  0.780  1.0
  O  O43  1  0.780  0.231  0.002  1.0
  O  O44  1  0.231  0.780  0.002  1.0
[/CIF]
.
The material structure described by CaAl2Si2(O4Cl)2 crystallizes in the trigonal R3m space group. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent Cl(1) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to three equivalent O(4) and three equivalent Cl(2) atoms. In the third Ca site, Ca(3) is bonded in a 6-coordinate geometry to three equivalent O(3) and three equivalent O(4) atoms. Al(1) is bonded to one O(1), one O(3), one O(5), and one O(6) atom to form AlO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. Si(1) is bonded to one O(2), one O(4), one O(5), and one O(6) atom to form SiO4 tetrahedra that share corners with two equivalent Al(1)O4 tetrahedra and corners with two equivalent Si(1)O4 tetrahedra. There are six inequivalent O sites. In the first O site, O(2) is bonded in a distorted bent 120 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(3) is bonded to one Ca(1), one Ca(3), and two equivalent Al(1) atoms to form distorted edge-sharing OCa2Al2 tetrahedra. In the third O site, O(4) is bonded in a 4-coordinate geometry to one Ca(2), one Ca(3), and two equivalent Si(1) atoms. In the fourth O site, O(5) is bonded in a linear geometry to one Al(1) and one Si(1) atom. In the fifth O site, O(6) is bonded in a linear geometry to one Al(1) and one Si(1) atom. In the sixth O site, O(1) is bonded in a bent 120 degrees geometry to two equivalent Al(1) atoms. There are two inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a single-bond geometry to one Ca(1) atom. In the second Cl site, Cl(2) is bonded in a single-bond geometry to one Ca(2) atom. is represented by the CIF file [CIF]
data_CaAl2Si2(ClO4)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.569
_cell_length_b   9.569
_cell_length_c   9.569
_cell_angle_alpha   95.540
_cell_angle_beta   95.540
_cell_angle_gamma   95.540
_symmetry_Int_Tables_number   1
_cell_volume   862.989
_cell_formula_units_Z   3
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  0.770  0.770  0.770  1.0
  Ca  Ca1  1  0.235  0.235  0.235  1.0
  Ca  Ca2  1  0.985  0.985  0.985  1.0
  Al  Al3  1  0.668  0.106  0.887  1.0
  Al  Al4  1  0.887  0.106  0.668  1.0
  Al  Al5  1  0.106  0.887  0.668  1.0
  Al  Al6  1  0.106  0.668  0.887  1.0
  Al  Al7  1  0.887  0.668  0.106  1.0
  Al  Al8  1  0.668  0.887  0.106  1.0
  Si  Si9  1  0.324  0.899  0.111  1.0
  Si  Si10  1  0.111  0.899  0.324  1.0
  Si  Si11  1  0.899  0.111  0.324  1.0
  Si  Si12  1  0.899  0.324  0.111  1.0
  Si  Si13  1  0.111  0.324  0.899  1.0
  Si  Si14  1  0.324  0.111  0.899  1.0
  Cl  Cl15  1  0.546  0.739  0.546  1.0
  Cl  Cl16  1  0.739  0.546  0.546  1.0
  Cl  Cl17  1  0.546  0.546  0.739  1.0
  Cl  Cl18  1  0.455  0.257  0.455  1.0
  Cl  Cl19  1  0.257  0.455  0.455  1.0
  Cl  Cl20  1  0.455  0.455  0.257  1.0
  O  O21  1  0.715  0.092  0.715  1.0
  O  O22  1  0.092  0.715  0.715  1.0
  O  O23  1  0.715  0.715  0.092  1.0
  O  O24  1  0.269  0.910  0.269  1.0
  O  O25  1  0.910  0.269  0.269  1.0
  O  O26  1  0.269  0.269  0.910  1.0
  O  O27  1  0.943  0.726  0.943  1.0
  O  O28  1  0.726  0.943  0.943  1.0
  O  O29  1  0.943  0.943  0.726  1.0
  O  O30  1  0.057  0.281  0.057  1.0
  O  O31  1  0.281  0.057  0.057  1.0
  O  O32  1  0.057  0.057  0.281  1.0
  O  O33  1  0.122  0.491  0.896  1.0
  O  O34  1  0.896  0.491  0.122  1.0
  O  O35  1  0.491  0.896  0.122  1.0
  O  O36  1  0.491  0.122  0.896  1.0
  O  O37  1  0.896  0.122  0.491  1.0
  O  O38  1  0.122  0.896  0.491  1.0
  O  O39  1  0.231  0.002  0.780  1.0
  O  O40  1  0.780  0.002  0.231  1.0
  O  O41  1  0.002  0.780  0.231  1.0
  O  O42  1  0.002  0.231  0.780  1.0
  O  O43  1  0.780  0.231  0.002  1.0
  O  O44  1  0.231  0.780  0.002  1.0
[/CIF]
.