The material structure described by U11Ni16 is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the trigonal R-3 space group. There are five inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to one U(1), one U(2), one U(4), one Ni(1), two equivalent Ni(2), two equivalent Ni(5), three equivalent Ni(3), and three equivalent Ni(4) atoms. In the second U site, U(2) is bonded in a 16-coordinate geometry to one U(2), three equivalent U(1), three equivalent Ni(3), three equivalent Ni(4), and six equivalent Ni(5) atoms. In the third U site, U(3) is bonded in a 13-coordinate geometry to one U(3), one U(4), one U(5), one Ni(3), one Ni(4), two equivalent Ni(5), three equivalent Ni(1), and three equivalent Ni(2) atoms. In the fourth U site, U(4) is bonded in a 13-coordinate geometry to one U(1), one U(3), two equivalent U(4), one Ni(2), one Ni(4), two equivalent Ni(3), two equivalent Ni(6), and three equivalent Ni(1) atoms. In the fifth U site, U(5) is bonded in a 13-coordinate geometry to three equivalent U(3), one Ni(6), three equivalent Ni(1), three equivalent Ni(2), and three equivalent Ni(4) atoms. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to one U(1), one U(5), three equivalent U(3), three equivalent U(4), one Ni(2), one Ni(3), one Ni(5), and one Ni(6) atom. In the second Ni site, Ni(2) is bonded to one U(4), one U(5), two equivalent U(1), three equivalent U(3), one Ni(1), one Ni(3), one Ni(5), and two equivalent Ni(4) atoms to form distorted NiU7Ni5 cuboctahedra that share corners with two equivalent Ni(2)U7Ni5 cuboctahedra, corners with two equivalent Ni(3)U7Ni5 cuboctahedra, corners with two equivalent Ni(4)U7Ni5 cuboctahedra, corners with four equivalent Ni(5)U6Ni6 cuboctahedra, edges with two equivalent Ni(2)U7Ni5 cuboctahedra, faces with two equivalent Ni(2)U7Ni5 cuboctahedra, faces with three equivalent Ni(5)U6Ni6 cuboctahedra, faces with four equivalent Ni(3)U7Ni5 cuboctahedra, and faces with four equivalent Ni(4)U7Ni5 cuboctahedra. In the third Ni site, Ni(3) is bonded to one U(2), one U(3), two equivalent U(4), three equivalent U(1), one Ni(1), one Ni(2), one Ni(4), and two equivalent Ni(5) atoms to form distorted NiU7Ni5 cuboctahedra that share corners with two equivalent Ni(2)U7Ni5 cuboctahedra, corners with two equivalent Ni(3)U7Ni5 cuboctahedra, corners with two equivalent Ni(4)U7Ni5 cuboctahedra, corners with four equivalent Ni(5)U6Ni6 cuboctahedra, edges with five equivalent Ni(3)U7Ni5 cuboctahedra, faces with four equivalent Ni(5)U6Ni6 cuboctahedra, faces with four equivalent Ni(2)U7Ni5 cuboctahedra, and faces with five equivalent Ni(4)U7Ni5 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to one U(2), one U(3), one U(4), one U(5), three equivalent U(1), one Ni(3), two equivalent Ni(2), and two equivalent Ni(4) atoms to form distorted NiU7Ni5 cuboctahedra that share corners with two equivalent Ni(2)U7Ni5 cuboctahedra, corners with two equivalent Ni(3)U7Ni5 cuboctahedra, corners with two equivalent Ni(4)U7Ni5 cuboctahedra, corners with three equivalent Ni(5)U6Ni6 cuboctahedra,  an edgeedge with one Ni(4)U7Ni5 cuboctahedra, edges with three equivalent Ni(5)U6Ni6 cuboctahedra, faces with two equivalent Ni(4)U7Ni5 cuboctahedra, faces with three equivalent Ni(5)U6Ni6 cuboctahedra, faces with four equivalent Ni(2)U7Ni5 cuboctahedra, and faces with five equivalent Ni(3)U7Ni5 cuboctahedra. In the fifth Ni site, Ni(5) is bonded to two equivalent U(1), two equivalent U(2), two equivalent U(3), one Ni(1), one Ni(2), two equivalent Ni(3), and two equivalent Ni(5) atoms to form NiU6Ni6 cuboctahedra that share corners with three equivalent Ni(4)U7Ni5 cuboctahedra, corners with four equivalent Ni(2)U7Ni5 cuboctahedra, corners with four equivalent Ni(3)U7Ni5 cuboctahedra,  an edgeedge with one Ni(5)U6Ni6 cuboctahedra, edges with three equivalent Ni(4)U7Ni5 cuboctahedra, faces with three equivalent Ni(2)U7Ni5 cuboctahedra, faces with three equivalent Ni(4)U7Ni5 cuboctahedra, faces with four equivalent Ni(5)U6Ni6 cuboctahedra, and faces with four equivalent Ni(3)U7Ni5 cuboctahedra. In the sixth Ni site, Ni(6) is bonded in a 8-coordinate geometry to one U(5), six equivalent U(4), one Ni(6), and three equivalent Ni(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_U11Ni16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.618
_cell_length_b   9.618
_cell_length_c   9.618
_cell_angle_alpha   74.972
_cell_angle_beta   74.972
_cell_angle_gamma   74.972
_symmetry_Int_Tables_number   1
_cell_volume   812.173
_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
  U  U0  1  0.885  0.414  0.577  1.0
  U  U1  1  0.586  0.423  0.115  1.0
  U  U2  1  0.428  0.428  0.428  1.0
  U  U3  1  0.413  0.948  0.126  1.0
  U  U4  1  0.572  0.572  0.572  1.0
  U  U5  1  0.587  0.052  0.874  1.0
  U  U6  1  0.721  0.146  0.057  1.0
  U  U7  1  0.423  0.115  0.586  1.0
  U  U8  1  0.948  0.126  0.413  1.0
  U  U9  1  0.874  0.587  0.052  1.0
  U  U10  1  0.194  0.194  0.194  1.0
  U  U11  1  0.414  0.577  0.885  1.0
  U  U12  1  0.126  0.413  0.948  1.0
  U  U13  1  0.146  0.057  0.721  1.0
  U  U14  1  0.115  0.586  0.423  1.0
  U  U15  1  0.052  0.874  0.587  1.0
  U  U16  1  0.577  0.885  0.414  1.0
  U  U17  1  0.806  0.806  0.806  1.0
  U  U18  1  0.854  0.943  0.279  1.0
  U  U19  1  0.057  0.721  0.146  1.0
  U  U20  1  0.279  0.854  0.943  1.0
  U  U21  1  0.943  0.279  0.854  1.0
  Ni  Ni22  1  0.845  0.112  0.721  1.0
  Ni  Ni23  1  0.992  0.574  0.727  1.0
  Ni  Ni24  1  0.649  0.334  0.814  1.0
  Ni  Ni25  1  0.186  0.351  0.666  1.0
  Ni  Ni26  1  0.559  0.817  0.725  1.0
  Ni  Ni27  1  0.888  0.279  0.155  1.0
  Ni  Ni28  1  0.725  0.559  0.817  1.0
  Ni  Ni29  1  0.814  0.649  0.334  1.0
  Ni  Ni30  1  0.743  0.415  0.348  1.0
  Ni  Ni31  1  0.666  0.186  0.351  1.0
  Ni  Ni32  1  0.415  0.348  0.743  1.0
  Ni  Ni33  1  0.426  0.273  0.008  1.0
  Ni  Ni34  1  0.721  0.845  0.112  1.0
  Ni  Ni35  1  0.062  0.062  0.062  1.0
  Ni  Ni36  1  0.727  0.992  0.574  1.0
  Ni  Ni37  1  0.273  0.008  0.426  1.0
  Ni  Ni38  1  0.008  0.426  0.273  1.0
  Ni  Ni39  1  0.938  0.938  0.938  1.0
  Ni  Ni40  1  0.574  0.727  0.992  1.0
  Ni  Ni41  1  0.334  0.814  0.649  1.0
  Ni  Ni42  1  0.817  0.725  0.559  1.0
  Ni  Ni43  1  0.441  0.183  0.275  1.0
  Ni  Ni44  1  0.351  0.666  0.186  1.0
  Ni  Ni45  1  0.183  0.275  0.441  1.0
  Ni  Ni46  1  0.348  0.743  0.415  1.0
  Ni  Ni47  1  0.585  0.652  0.257  1.0
  Ni  Ni48  1  0.275  0.441  0.183  1.0
  Ni  Ni49  1  0.257  0.585  0.652  1.0
  Ni  Ni50  1  0.112  0.721  0.845  1.0
  Ni  Ni51  1  0.155  0.888  0.279  1.0
  Ni  Ni52  1  0.652  0.257  0.585  1.0
  Ni  Ni53  1  0.279  0.155  0.888  1.0
[/CIF]
.
The material structure described by U11Ni16 is Frank-Kasper $\mu$ Phase-like structured and crystallizes in the trigonal R-3 space group. There are five inequivalent U sites. In the first U site, U(1) is bonded in a 14-coordinate geometry to one U(1), one U(2), one U(4), one Ni(1), two equivalent Ni(2), two equivalent Ni(5), three equivalent Ni(3), and three equivalent Ni(4) atoms. In the second U site, U(2) is bonded in a 16-coordinate geometry to one U(2), three equivalent U(1), three equivalent Ni(3), three equivalent Ni(4), and six equivalent Ni(5) atoms. In the third U site, U(3) is bonded in a 13-coordinate geometry to one U(3), one U(4), one U(5), one Ni(3), one Ni(4), two equivalent Ni(5), three equivalent Ni(1), and three equivalent Ni(2) atoms. In the fourth U site, U(4) is bonded in a 13-coordinate geometry to one U(1), one U(3), two equivalent U(4), one Ni(2), one Ni(4), two equivalent Ni(3), two equivalent Ni(6), and three equivalent Ni(1) atoms. In the fifth U site, U(5) is bonded in a 13-coordinate geometry to three equivalent U(3), one Ni(6), three equivalent Ni(1), three equivalent Ni(2), and three equivalent Ni(4) atoms. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a 12-coordinate geometry to one U(1), one U(5), three equivalent U(3), three equivalent U(4), one Ni(2), one Ni(3), one Ni(5), and one Ni(6) atom. In the second Ni site, Ni(2) is bonded to one U(4), one U(5), two equivalent U(1), three equivalent U(3), one Ni(1), one Ni(3), one Ni(5), and two equivalent Ni(4) atoms to form distorted NiU7Ni5 cuboctahedra that share corners with two equivalent Ni(2)U7Ni5 cuboctahedra, corners with two equivalent Ni(3)U7Ni5 cuboctahedra, corners with two equivalent Ni(4)U7Ni5 cuboctahedra, corners with four equivalent Ni(5)U6Ni6 cuboctahedra, edges with two equivalent Ni(2)U7Ni5 cuboctahedra, faces with two equivalent Ni(2)U7Ni5 cuboctahedra, faces with three equivalent Ni(5)U6Ni6 cuboctahedra, faces with four equivalent Ni(3)U7Ni5 cuboctahedra, and faces with four equivalent Ni(4)U7Ni5 cuboctahedra. In the third Ni site, Ni(3) is bonded to one U(2), one U(3), two equivalent U(4), three equivalent U(1), one Ni(1), one Ni(2), one Ni(4), and two equivalent Ni(5) atoms to form distorted NiU7Ni5 cuboctahedra that share corners with two equivalent Ni(2)U7Ni5 cuboctahedra, corners with two equivalent Ni(3)U7Ni5 cuboctahedra, corners with two equivalent Ni(4)U7Ni5 cuboctahedra, corners with four equivalent Ni(5)U6Ni6 cuboctahedra, edges with five equivalent Ni(3)U7Ni5 cuboctahedra, faces with four equivalent Ni(5)U6Ni6 cuboctahedra, faces with four equivalent Ni(2)U7Ni5 cuboctahedra, and faces with five equivalent Ni(4)U7Ni5 cuboctahedra. In the fourth Ni site, Ni(4) is bonded to one U(2), one U(3), one U(4), one U(5), three equivalent U(1), one Ni(3), two equivalent Ni(2), and two equivalent Ni(4) atoms to form distorted NiU7Ni5 cuboctahedra that share corners with two equivalent Ni(2)U7Ni5 cuboctahedra, corners with two equivalent Ni(3)U7Ni5 cuboctahedra, corners with two equivalent Ni(4)U7Ni5 cuboctahedra, corners with three equivalent Ni(5)U6Ni6 cuboctahedra,  an edgeedge with one Ni(4)U7Ni5 cuboctahedra, edges with three equivalent Ni(5)U6Ni6 cuboctahedra, faces with two equivalent Ni(4)U7Ni5 cuboctahedra, faces with three equivalent Ni(5)U6Ni6 cuboctahedra, faces with four equivalent Ni(2)U7Ni5 cuboctahedra, and faces with five equivalent Ni(3)U7Ni5 cuboctahedra. In the fifth Ni site, Ni(5) is bonded to two equivalent U(1), two equivalent U(2), two equivalent U(3), one Ni(1), one Ni(2), two equivalent Ni(3), and two equivalent Ni(5) atoms to form NiU6Ni6 cuboctahedra that share corners with three equivalent Ni(4)U7Ni5 cuboctahedra, corners with four equivalent Ni(2)U7Ni5 cuboctahedra, corners with four equivalent Ni(3)U7Ni5 cuboctahedra,  an edgeedge with one Ni(5)U6Ni6 cuboctahedra, edges with three equivalent Ni(4)U7Ni5 cuboctahedra, faces with three equivalent Ni(2)U7Ni5 cuboctahedra, faces with three equivalent Ni(4)U7Ni5 cuboctahedra, faces with four equivalent Ni(5)U6Ni6 cuboctahedra, and faces with four equivalent Ni(3)U7Ni5 cuboctahedra. In the sixth Ni site, Ni(6) is bonded in a 8-coordinate geometry to one U(5), six equivalent U(4), one Ni(6), and three equivalent Ni(1) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_U11Ni16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.618
_cell_length_b   9.618
_cell_length_c   9.618
_cell_angle_alpha   74.972
_cell_angle_beta   74.972
_cell_angle_gamma   74.972
_symmetry_Int_Tables_number   1
_cell_volume   812.173
_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
  U  U0  1  0.885  0.414  0.577  1.0
  U  U1  1  0.586  0.423  0.115  1.0
  U  U2  1  0.428  0.428  0.428  1.0
  U  U3  1  0.413  0.948  0.126  1.0
  U  U4  1  0.572  0.572  0.572  1.0
  U  U5  1  0.587  0.052  0.874  1.0
  U  U6  1  0.721  0.146  0.057  1.0
  U  U7  1  0.423  0.115  0.586  1.0
  U  U8  1  0.948  0.126  0.413  1.0
  U  U9  1  0.874  0.587  0.052  1.0
  U  U10  1  0.194  0.194  0.194  1.0
  U  U11  1  0.414  0.577  0.885  1.0
  U  U12  1  0.126  0.413  0.948  1.0
  U  U13  1  0.146  0.057  0.721  1.0
  U  U14  1  0.115  0.586  0.423  1.0
  U  U15  1  0.052  0.874  0.587  1.0
  U  U16  1  0.577  0.885  0.414  1.0
  U  U17  1  0.806  0.806  0.806  1.0
  U  U18  1  0.854  0.943  0.279  1.0
  U  U19  1  0.057  0.721  0.146  1.0
  U  U20  1  0.279  0.854  0.943  1.0
  U  U21  1  0.943  0.279  0.854  1.0
  Ni  Ni22  1  0.845  0.112  0.721  1.0
  Ni  Ni23  1  0.992  0.574  0.727  1.0
  Ni  Ni24  1  0.649  0.334  0.814  1.0
  Ni  Ni25  1  0.186  0.351  0.666  1.0
  Ni  Ni26  1  0.559  0.817  0.725  1.0
  Ni  Ni27  1  0.888  0.279  0.155  1.0
  Ni  Ni28  1  0.725  0.559  0.817  1.0
  Ni  Ni29  1  0.814  0.649  0.334  1.0
  Ni  Ni30  1  0.743  0.415  0.348  1.0
  Ni  Ni31  1  0.666  0.186  0.351  1.0
  Ni  Ni32  1  0.415  0.348  0.743  1.0
  Ni  Ni33  1  0.426  0.273  0.008  1.0
  Ni  Ni34  1  0.721  0.845  0.112  1.0
  Ni  Ni35  1  0.062  0.062  0.062  1.0
  Ni  Ni36  1  0.727  0.992  0.574  1.0
  Ni  Ni37  1  0.273  0.008  0.426  1.0
  Ni  Ni38  1  0.008  0.426  0.273  1.0
  Ni  Ni39  1  0.938  0.938  0.938  1.0
  Ni  Ni40  1  0.574  0.727  0.992  1.0
  Ni  Ni41  1  0.334  0.814  0.649  1.0
  Ni  Ni42  1  0.817  0.725  0.559  1.0
  Ni  Ni43  1  0.441  0.183  0.275  1.0
  Ni  Ni44  1  0.351  0.666  0.186  1.0
  Ni  Ni45  1  0.183  0.275  0.441  1.0
  Ni  Ni46  1  0.348  0.743  0.415  1.0
  Ni  Ni47  1  0.585  0.652  0.257  1.0
  Ni  Ni48  1  0.275  0.441  0.183  1.0
  Ni  Ni49  1  0.257  0.585  0.652  1.0
  Ni  Ni50  1  0.112  0.721  0.845  1.0
  Ni  Ni51  1  0.155  0.888  0.279  1.0
  Ni  Ni52  1  0.652  0.257  0.585  1.0
  Ni  Ni53  1  0.279  0.155  0.888  1.0
[/CIF]
.