The crystal structure described by Ca4UAl2(SiO5)3 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent O(2), three equivalent O(3), and six equivalent O(1) atoms to form CaO12 cuboctahedra that share corners with three equivalent Ca(2)O12 cuboctahedra, corners with nine equivalent Ca(1)O12 cuboctahedra, faces with three equivalent Ca(2)O12 cuboctahedra, faces with three equivalent U(1)O12 cuboctahedra,  a faceface with one Si(2)O6 octahedra, faces with three equivalent Si(1)O6 octahedra, and faces with four equivalent Al(1)O6 octahedra. In the second Ca site, Ca(2) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form CaO12 cuboctahedra that share corners with three equivalent Ca(1)O12 cuboctahedra, corners with three equivalent U(1)O12 cuboctahedra, corners with six equivalent Ca(2)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, faces with three equivalent Ca(2)O12 cuboctahedra,  a faceface with one Al(1)O6 octahedra, faces with three equivalent Si(2)O6 octahedra, and faces with four equivalent Si(1)O6 octahedra. U(1) is bonded to six equivalent O(1) and six equivalent O(3) atoms to form UO12 cuboctahedra that share corners with six equivalent Ca(2)O12 cuboctahedra, corners with six equivalent U(1)O12 cuboctahedra, faces with six equivalent Ca(1)O12 cuboctahedra, faces with two equivalent Si(1)O6 octahedra, and faces with six equivalent Al(1)O6 octahedra. Al(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form AlO6 octahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Si(1)O6 octahedra,  a faceface with one Ca(2)O12 cuboctahedra, faces with three equivalent U(1)O12 cuboctahedra, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SiO6 octahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Si(2)O6 octahedra,  a faceface with one U(1)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, and faces with four equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second Si site, Si(2) is bonded to six equivalent O(2) atoms to form SiO6 octahedra that share corners with six equivalent Si(1)O6 octahedra, faces with two equivalent Ca(1)O12 cuboctahedra, and faces with six equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted linear geometry to two equivalent Ca(1), two equivalent U(1), and two equivalent Al(1) atoms. In the second O site, O(1) is bonded in a distorted linear geometry to one Ca(2), two equivalent Ca(1), one U(1), one Al(1), and one Si(1) atom. In the third O site, O(2) is bonded to one Ca(1), three equivalent Ca(2), one Si(1), and one Si(2) atom to form a mixture of distorted corner, face, and edge-sharing OCa4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca4UAl2(SiO5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.949
_cell_length_b   10.949
_cell_length_c   10.949
_cell_angle_alpha   27.409
_cell_angle_beta   27.409
_cell_angle_gamma   27.409
_symmetry_Int_Tables_number   1
_cell_volume   245.473
_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  0.401  0.401  0.401  1.0
  Ca  Ca1  1  0.800  0.800  0.800  1.0
  Ca  Ca2  1  0.200  0.200  0.200  1.0
  Ca  Ca3  1  0.599  0.599  0.599  1.0
  U  U4  1  0.000  0.000  0.000  1.0
  Al  Al5  1  0.701  0.701  0.701  1.0
  Al  Al6  1  0.299  0.299  0.299  1.0
  Si  Si7  1  0.101  0.101  0.101  1.0
  Si  Si8  1  0.500  0.500  0.500  1.0
  Si  Si9  1  0.899  0.899  0.899  1.0
  O  O10  1  0.091  0.091  0.616  1.0
  O  O11  1  0.699  0.699  0.200  1.0
  O  O12  1  0.301  0.301  0.800  1.0
  O  O13  1  0.909  0.909  0.384  1.0
  O  O14  1  0.500  0.500  0.000  1.0
  O  O15  1  0.000  0.500  0.500  1.0
  O  O16  1  0.616  0.091  0.091  1.0
  O  O17  1  0.200  0.699  0.699  1.0
  O  O18  1  0.800  0.301  0.301  1.0
  O  O19  1  0.384  0.909  0.909  1.0
  O  O20  1  0.500  0.000  0.500  1.0
  O  O21  1  0.091  0.616  0.091  1.0
  O  O22  1  0.699  0.200  0.699  1.0
  O  O23  1  0.301  0.800  0.301  1.0
  O  O24  1  0.909  0.384  0.909  1.0
[/CIF]
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The crystal structure described by Ca4UAl2(SiO5)3 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal R-3m space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to three equivalent O(2), three equivalent O(3), and six equivalent O(1) atoms to form CaO12 cuboctahedra that share corners with three equivalent Ca(2)O12 cuboctahedra, corners with nine equivalent Ca(1)O12 cuboctahedra, faces with three equivalent Ca(2)O12 cuboctahedra, faces with three equivalent U(1)O12 cuboctahedra,  a faceface with one Si(2)O6 octahedra, faces with three equivalent Si(1)O6 octahedra, and faces with four equivalent Al(1)O6 octahedra. In the second Ca site, Ca(2) is bonded to three equivalent O(1) and nine equivalent O(2) atoms to form CaO12 cuboctahedra that share corners with three equivalent Ca(1)O12 cuboctahedra, corners with three equivalent U(1)O12 cuboctahedra, corners with six equivalent Ca(2)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, faces with three equivalent Ca(2)O12 cuboctahedra,  a faceface with one Al(1)O6 octahedra, faces with three equivalent Si(2)O6 octahedra, and faces with four equivalent Si(1)O6 octahedra. U(1) is bonded to six equivalent O(1) and six equivalent O(3) atoms to form UO12 cuboctahedra that share corners with six equivalent Ca(2)O12 cuboctahedra, corners with six equivalent U(1)O12 cuboctahedra, faces with six equivalent Ca(1)O12 cuboctahedra, faces with two equivalent Si(1)O6 octahedra, and faces with six equivalent Al(1)O6 octahedra. Al(1) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form AlO6 octahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Si(1)O6 octahedra,  a faceface with one Ca(2)O12 cuboctahedra, faces with three equivalent U(1)O12 cuboctahedra, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form SiO6 octahedra that share corners with three equivalent Al(1)O6 octahedra, corners with three equivalent Si(2)O6 octahedra,  a faceface with one U(1)O12 cuboctahedra, faces with three equivalent Ca(1)O12 cuboctahedra, and faces with four equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-4°. In the second Si site, Si(2) is bonded to six equivalent O(2) atoms to form SiO6 octahedra that share corners with six equivalent Si(1)O6 octahedra, faces with two equivalent Ca(1)O12 cuboctahedra, and faces with six equivalent Ca(2)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are three inequivalent O sites. In the first O site, O(3) is bonded in a distorted linear geometry to two equivalent Ca(1), two equivalent U(1), and two equivalent Al(1) atoms. In the second O site, O(1) is bonded in a distorted linear geometry to one Ca(2), two equivalent Ca(1), one U(1), one Al(1), and one Si(1) atom. In the third O site, O(2) is bonded to one Ca(1), three equivalent Ca(2), one Si(1), and one Si(2) atom to form a mixture of distorted corner, face, and edge-sharing OCa4Si2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca4UAl2(SiO5)3
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   10.949
_cell_length_b   10.949
_cell_length_c   10.949
_cell_angle_alpha   27.409
_cell_angle_beta   27.409
_cell_angle_gamma   27.409
_symmetry_Int_Tables_number   1
_cell_volume   245.473
_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  0.401  0.401  0.401  1.0
  Ca  Ca1  1  0.800  0.800  0.800  1.0
  Ca  Ca2  1  0.200  0.200  0.200  1.0
  Ca  Ca3  1  0.599  0.599  0.599  1.0
  U  U4  1  0.000  0.000  0.000  1.0
  Al  Al5  1  0.701  0.701  0.701  1.0
  Al  Al6  1  0.299  0.299  0.299  1.0
  Si  Si7  1  0.101  0.101  0.101  1.0
  Si  Si8  1  0.500  0.500  0.500  1.0
  Si  Si9  1  0.899  0.899  0.899  1.0
  O  O10  1  0.091  0.091  0.616  1.0
  O  O11  1  0.699  0.699  0.200  1.0
  O  O12  1  0.301  0.301  0.800  1.0
  O  O13  1  0.909  0.909  0.384  1.0
  O  O14  1  0.500  0.500  0.000  1.0
  O  O15  1  0.000  0.500  0.500  1.0
  O  O16  1  0.616  0.091  0.091  1.0
  O  O17  1  0.200  0.699  0.699  1.0
  O  O18  1  0.800  0.301  0.301  1.0
  O  O19  1  0.384  0.909  0.909  1.0
  O  O20  1  0.500  0.000  0.500  1.0
  O  O21  1  0.091  0.616  0.091  1.0
  O  O22  1  0.699  0.200  0.699  1.0
  O  O23  1  0.301  0.800  0.301  1.0
  O  O24  1  0.909  0.384  0.909  1.0
[/CIF]
.