The material described by K2Ca4U(SiO4)4 is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. K(1) is bonded in a 6-coordinate geometry to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(4), one O(5), one O(7), one O(8), two equivalent O(1), and two equivalent O(2) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(5), and two equivalent O(7) atoms. U(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms to form UO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, 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  a cornercorner with one U(1)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. In the second Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ca(2), two equivalent Ca(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one U(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1), one Ca(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one U(1), and one Si(2) atom. In the seventh O site, O(7) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one K(1), one Ca(1), and one U(1) atom. is represented by the CIF card [CIF]
data_K2Ca4U(SiO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.722
_cell_length_b   6.766
_cell_length_c   9.811
_cell_angle_alpha   98.674
_cell_angle_beta   93.174
_cell_angle_gamma   112.435
_symmetry_Int_Tables_number   1
_cell_volume   404.583
_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
  K  K0  1  0.672  0.322  0.545  1.0
  K  K1  1  0.328  0.678  0.455  1.0
  Ca  Ca2  1  0.226  0.968  0.887  1.0
  Ca  Ca3  1  0.774  0.032  0.113  1.0
  Ca  Ca4  1  0.742  0.484  0.928  1.0
  Ca  Ca5  1  0.258  0.516  0.072  1.0
  U  U6  1  0.000  0.000  0.500  1.0
  Si  Si7  1  0.674  0.915  0.788  1.0
  Si  Si8  1  0.326  0.085  0.212  1.0
  Si  Si9  1  0.246  0.477  0.766  1.0
  Si  Si10  1  0.754  0.523  0.234  1.0
  O  O11  1  0.626  0.105  0.886  1.0
  O  O12  1  0.374  0.895  0.114  1.0
  O  O13  1  0.837  0.843  0.878  1.0
  O  O14  1  0.163  0.157  0.122  1.0
  O  O15  1  0.744  0.974  0.636  1.0
  O  O16  1  0.256  0.026  0.364  1.0
  O  O17  1  0.439  0.704  0.738  1.0
  O  O18  1  0.561  0.296  0.262  1.0
  O  O19  1  0.080  0.553  0.855  1.0
  O  O20  1  0.920  0.447  0.145  1.0
  O  O21  1  0.147  0.346  0.606  1.0
  O  O22  1  0.853  0.654  0.394  1.0
  O  O23  1  0.354  0.358  0.861  1.0
  O  O24  1  0.646  0.642  0.139  1.0
  O  O25  1  0.841  0.074  0.366  1.0
  O  O26  1  0.159  0.926  0.634  1.0
[/CIF]
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The material described by K2Ca4U(SiO4)4 is Esseneite-derived structured and crystallizes in the triclinic P-1 space group. K(1) is bonded in a 6-coordinate geometry to one O(4), one O(8), two equivalent O(3), and two equivalent O(6) atoms. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded in a 8-coordinate geometry to one O(4), one O(5), one O(7), one O(8), two equivalent O(1), and two equivalent O(2) atoms. In the second Ca site, Ca(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(5), and two equivalent O(7) atoms. U(1) is bonded to two equivalent O(3), two equivalent O(6), and two equivalent O(8) atoms to form UO6 octahedra that share corners with two equivalent Si(1)O4 tetrahedra and corners with two equivalent Si(2)O4 tetrahedra. There are two inequivalent Si sites. In the first Si site, 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  a cornercorner with one U(1)O6 octahedra and  a cornercorner with one Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. In the second Si site, Si(2) is bonded to one O(4), one O(5), one O(6), and one O(7) atom to form SiO4 tetrahedra that share  a cornercorner with one U(1)O6 octahedra and  a cornercorner with one Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 44°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to one Ca(2), two equivalent Ca(1), and one Si(1) atom to form a mixture of distorted corner and edge-sharing OCa3Si tetrahedra. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Ca(2), two equivalent Ca(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent K(1), one U(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted bent 150 degrees geometry to one K(1), one Ca(1), one Si(1), and one Si(2) atom. In the fifth O site, O(5) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the sixth O site, O(6) is bonded in a 4-coordinate geometry to two equivalent K(1), one U(1), and one Si(2) atom. In the seventh O site, O(7) is bonded to one Ca(1), two equivalent Ca(2), and one Si(2) atom to form a mixture of distorted corner and edge-sharing OCa3Si trigonal pyramids. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one K(1), one Ca(1), and one U(1) atom. is represented by the CIF card [CIF]
data_K2Ca4U(SiO4)4
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.722
_cell_length_b   6.766
_cell_length_c   9.811
_cell_angle_alpha   98.674
_cell_angle_beta   93.174
_cell_angle_gamma   112.435
_symmetry_Int_Tables_number   1
_cell_volume   404.583
_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
  K  K0  1  0.672  0.322  0.545  1.0
  K  K1  1  0.328  0.678  0.455  1.0
  Ca  Ca2  1  0.226  0.968  0.887  1.0
  Ca  Ca3  1  0.774  0.032  0.113  1.0
  Ca  Ca4  1  0.742  0.484  0.928  1.0
  Ca  Ca5  1  0.258  0.516  0.072  1.0
  U  U6  1  0.000  0.000  0.500  1.0
  Si  Si7  1  0.674  0.915  0.788  1.0
  Si  Si8  1  0.326  0.085  0.212  1.0
  Si  Si9  1  0.246  0.477  0.766  1.0
  Si  Si10  1  0.754  0.523  0.234  1.0
  O  O11  1  0.626  0.105  0.886  1.0
  O  O12  1  0.374  0.895  0.114  1.0
  O  O13  1  0.837  0.843  0.878  1.0
  O  O14  1  0.163  0.157  0.122  1.0
  O  O15  1  0.744  0.974  0.636  1.0
  O  O16  1  0.256  0.026  0.364  1.0
  O  O17  1  0.439  0.704  0.738  1.0
  O  O18  1  0.561  0.296  0.262  1.0
  O  O19  1  0.080  0.553  0.855  1.0
  O  O20  1  0.920  0.447  0.145  1.0
  O  O21  1  0.147  0.346  0.606  1.0
  O  O22  1  0.853  0.654  0.394  1.0
  O  O23  1  0.354  0.358  0.861  1.0
  O  O24  1  0.646  0.642  0.139  1.0
  O  O25  1  0.841  0.074  0.366  1.0
  O  O26  1  0.159  0.926  0.634  1.0
[/CIF]
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