The material structure described by K4CaUSi4O14 crystallizes in the tetragonal P-4n2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 2-coordinate geometry to two equivalent O(2) atoms. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with two equivalent U(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedra are not tilted. U(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form UO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedra are not tilted. Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one U(1)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 22-28°. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 2-coordinate geometry to one K(1), one U(1), and one Si(1) atom. In the second O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the third O site, O(5) is bonded in a linear geometry to one K(1) and two equivalent Si(1) atoms. In the fourth O site, O(1) is bonded in a linear geometry to one Ca(1) and one U(1) atom. In the fifth O site, O(2) is bonded in a 1-coordinate geometry to one K(1), one K(2), one Ca(1), and one Si(1) atom. is represented by the CIF card [CIF]
data_K4CaU(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.391
_cell_length_b   9.391
_cell_length_c   8.346
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   736.113
_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
  K  K0  1  0.344  0.156  0.250  1.0
  K  K1  1  0.156  0.656  0.750  1.0
  K  K2  1  0.656  0.844  0.250  1.0
  K  K3  1  0.844  0.344  0.750  1.0
  K  K4  1  0.210  0.710  0.250  1.0
  K  K5  1  0.290  0.210  0.750  1.0
  K  K6  1  0.710  0.790  0.750  1.0
  K  K7  1  0.790  0.290  0.250  1.0
  Ca  Ca8  1  0.500  0.500  0.000  1.0
  Ca  Ca9  1  0.000  0.000  0.500  1.0
  U  U10  1  0.500  0.500  0.500  1.0
  U  U11  1  0.000  0.000  0.000  1.0
  Si  Si12  1  0.881  0.617  0.447  1.0
  Si  Si13  1  0.619  0.117  0.947  1.0
  Si  Si14  1  0.617  0.119  0.553  1.0
  Si  Si15  1  0.883  0.619  0.053  1.0
  Si  Si16  1  0.119  0.383  0.447  1.0
  Si  Si17  1  0.381  0.883  0.947  1.0
  Si  Si18  1  0.383  0.881  0.553  1.0
  Si  Si19  1  0.117  0.381  0.053  1.0
  O  O20  1  0.500  0.500  0.277  1.0
  O  O21  1  0.000  0.000  0.777  1.0
  O  O22  1  0.500  0.500  0.723  1.0
  O  O23  1  0.000  0.000  0.223  1.0
  O  O24  1  0.912  0.769  0.519  1.0
  O  O25  1  0.588  0.269  0.019  1.0
  O  O26  1  0.769  0.088  0.481  1.0
  O  O27  1  0.731  0.588  0.981  1.0
  O  O28  1  0.088  0.231  0.519  1.0
  O  O29  1  0.412  0.731  0.019  1.0
  O  O30  1  0.231  0.912  0.481  1.0
  O  O31  1  0.269  0.412  0.981  1.0
  O  O32  1  0.729  0.551  0.506  1.0
  O  O33  1  0.771  0.051  0.006  1.0
  O  O34  1  0.551  0.271  0.494  1.0
  O  O35  1  0.949  0.771  0.994  1.0
  O  O36  1  0.271  0.449  0.506  1.0
  O  O37  1  0.229  0.949  0.006  1.0
  O  O38  1  0.449  0.729  0.494  1.0
  O  O39  1  0.051  0.229  0.994  1.0
  O  O40  1  0.000  0.500  0.508  1.0
  O  O41  1  0.500  0.000  0.008  1.0
  O  O42  1  0.500  0.000  0.492  1.0
  O  O43  1  0.000  0.500  0.992  1.0
  O  O44  1  0.885  0.615  0.250  1.0
  O  O45  1  0.615  0.115  0.750  1.0
  O  O46  1  0.115  0.385  0.250  1.0
  O  O47  1  0.385  0.885  0.750  1.0
[/CIF]
.
The material structure described by K4CaUSi4O14 crystallizes in the tetragonal P-4n2 space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 7-coordinate geometry to one O(5), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second K site, K(2) is bonded in a 2-coordinate geometry to two equivalent O(2) atoms. Ca(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form CaO6 octahedra that share corners with two equivalent U(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedra are not tilted. U(1) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form UO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra and corners with four equivalent Si(1)O4 tetrahedra. The corner-sharing octahedra are not tilted. Si(1) is bonded to one O(2), one O(3), one O(4), and one O(5) atom to form SiO4 tetrahedra that share  a cornercorner with one Ca(1)O6 octahedra,  a cornercorner with one U(1)O6 octahedra, and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 22-28°. There are five inequivalent O sites. In the first O site, O(3) is bonded in a 2-coordinate geometry to one K(1), one U(1), and one Si(1) atom. In the second O site, O(4) is bonded in a distorted bent 150 degrees geometry to two equivalent K(1) and two equivalent Si(1) atoms. In the third O site, O(5) is bonded in a linear geometry to one K(1) and two equivalent Si(1) atoms. In the fourth O site, O(1) is bonded in a linear geometry to one Ca(1) and one U(1) atom. In the fifth O site, O(2) is bonded in a 1-coordinate geometry to one K(1), one K(2), one Ca(1), and one Si(1) atom. is represented by the CIF card [CIF]
data_K4CaU(Si2O7)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.391
_cell_length_b   9.391
_cell_length_c   8.346
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   736.113
_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
  K  K0  1  0.344  0.156  0.250  1.0
  K  K1  1  0.156  0.656  0.750  1.0
  K  K2  1  0.656  0.844  0.250  1.0
  K  K3  1  0.844  0.344  0.750  1.0
  K  K4  1  0.210  0.710  0.250  1.0
  K  K5  1  0.290  0.210  0.750  1.0
  K  K6  1  0.710  0.790  0.750  1.0
  K  K7  1  0.790  0.290  0.250  1.0
  Ca  Ca8  1  0.500  0.500  0.000  1.0
  Ca  Ca9  1  0.000  0.000  0.500  1.0
  U  U10  1  0.500  0.500  0.500  1.0
  U  U11  1  0.000  0.000  0.000  1.0
  Si  Si12  1  0.881  0.617  0.447  1.0
  Si  Si13  1  0.619  0.117  0.947  1.0
  Si  Si14  1  0.617  0.119  0.553  1.0
  Si  Si15  1  0.883  0.619  0.053  1.0
  Si  Si16  1  0.119  0.383  0.447  1.0
  Si  Si17  1  0.381  0.883  0.947  1.0
  Si  Si18  1  0.383  0.881  0.553  1.0
  Si  Si19  1  0.117  0.381  0.053  1.0
  O  O20  1  0.500  0.500  0.277  1.0
  O  O21  1  0.000  0.000  0.777  1.0
  O  O22  1  0.500  0.500  0.723  1.0
  O  O23  1  0.000  0.000  0.223  1.0
  O  O24  1  0.912  0.769  0.519  1.0
  O  O25  1  0.588  0.269  0.019  1.0
  O  O26  1  0.769  0.088  0.481  1.0
  O  O27  1  0.731  0.588  0.981  1.0
  O  O28  1  0.088  0.231  0.519  1.0
  O  O29  1  0.412  0.731  0.019  1.0
  O  O30  1  0.231  0.912  0.481  1.0
  O  O31  1  0.269  0.412  0.981  1.0
  O  O32  1  0.729  0.551  0.506  1.0
  O  O33  1  0.771  0.051  0.006  1.0
  O  O34  1  0.551  0.271  0.494  1.0
  O  O35  1  0.949  0.771  0.994  1.0
  O  O36  1  0.271  0.449  0.506  1.0
  O  O37  1  0.229  0.949  0.006  1.0
  O  O38  1  0.449  0.729  0.494  1.0
  O  O39  1  0.051  0.229  0.994  1.0
  O  O40  1  0.000  0.500  0.508  1.0
  O  O41  1  0.500  0.000  0.008  1.0
  O  O42  1  0.500  0.000  0.492  1.0
  O  O43  1  0.000  0.500  0.992  1.0
  O  O44  1  0.885  0.615  0.250  1.0
  O  O45  1  0.615  0.115  0.750  1.0
  O  O46  1  0.115  0.385  0.250  1.0
  O  O47  1  0.385  0.885  0.750  1.0
[/CIF]
.