The material described by YZr2Co9 is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the trigonal R3m space group. Y(1) is bonded in a 16-coordinate geometry to one Zr(2), three equivalent Zr(1), three equivalent Co(2), three equivalent Co(5), and six equivalent Co(1) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a 15-coordinate geometry to three equivalent Y(1), three equivalent Co(1), three equivalent Co(5), and six equivalent Co(2) atoms. In the second Zr site, Zr(2) is bonded in a distorted hexagonal planar geometry to one Y(1), three equivalent Co(3), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(2) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent Y(1), one Zr(1), two equivalent Zr(2), one Co(3), one Co(4), one Co(5), and four equivalent Co(1) atoms to form distorted CoY2Zr3Co7 cuboctahedra that share corners with two equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with two equivalent Co(3)Zr3Co6 cuboctahedra, corners with two equivalent Co(4)Zr3Co6 cuboctahedra, corners with four equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with eleven equivalent Co(2)YZr4Co7 cuboctahedra, edges with two equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with two equivalent Co(3)Zr3Co6 cuboctahedra, edges with two equivalent Co(4)Zr3Co6 cuboctahedra, edges with six equivalent Co(2)YZr4Co7 cuboctahedra,  a faceface with one Co(3)Zr3Co6 cuboctahedra,  a faceface with one Co(4)Zr3Co6 cuboctahedra, faces with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, faces with three equivalent Co(2)YZr4Co7 cuboctahedra, and faces with eight equivalent Co(1)Y2Zr3Co7 cuboctahedra. In the second Co site, Co(2) is bonded to one Y(1), two equivalent Zr(1), two equivalent Zr(2), one Co(3), one Co(4), one Co(5), and four equivalent Co(2) atoms to form distorted CoYZr4Co7 cuboctahedra that share corners with two equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with two equivalent Co(3)Zr3Co6 cuboctahedra, corners with two equivalent Co(4)Zr3Co6 cuboctahedra, corners with four equivalent Co(2)YZr4Co7 cuboctahedra, corners with eleven equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with two equivalent Co(2)YZr4Co7 cuboctahedra, edges with two equivalent Co(3)Zr3Co6 cuboctahedra, edges with two equivalent Co(4)Zr3Co6 cuboctahedra, edges with six equivalent Co(1)Y2Zr3Co7 cuboctahedra,  a faceface with one Co(3)Zr3Co6 cuboctahedra,  a faceface with one Co(4)Zr3Co6 cuboctahedra, faces with three equivalent Co(1)Y2Zr3Co7 cuboctahedra, faces with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, and faces with eight equivalent Co(2)YZr4Co7 cuboctahedra. In the third Co site, Co(3) is bonded to three equivalent Zr(2), three equivalent Co(1), and three equivalent Co(2) atoms to form distorted CoZr3Co6 cuboctahedra that share corners with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with three equivalent Co(4)Zr3Co6 cuboctahedra, corners with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with six equivalent Co(2)YZr4Co7 cuboctahedra, corners with six equivalent Co(3)Zr3Co6 cuboctahedra, edges with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with six equivalent Co(2)YZr4Co7 cuboctahedra,  a faceface with one Co(5)Y3Zr3Co6 cuboctahedra, faces with three equivalent Co(1)Y2Zr3Co7 cuboctahedra, faces with three equivalent Co(2)YZr4Co7 cuboctahedra, and faces with three equivalent Co(4)Zr3Co6 cuboctahedra. In the fourth Co site, Co(4) is bonded to three equivalent Zr(2), three equivalent Co(1), and three equivalent Co(2) atoms to form distorted CoZr3Co6 cuboctahedra that share corners with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with three equivalent Co(3)Zr3Co6 cuboctahedra, corners with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with six equivalent Co(2)YZr4Co7 cuboctahedra, corners with six equivalent Co(4)Zr3Co6 cuboctahedra, edges with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with six equivalent Co(2)YZr4Co7 cuboctahedra,  a faceface with one Co(5)Y3Zr3Co6 cuboctahedra, faces with three equivalent Co(1)Y2Zr3Co7 cuboctahedra, faces with three equivalent Co(2)YZr4Co7 cuboctahedra, and faces with three equivalent Co(3)Zr3Co6 cuboctahedra. In the fifth Co site, Co(5) is bonded to three equivalent Y(1), three equivalent Zr(1), three equivalent Co(1), and three equivalent Co(2) atoms to form CoY3Zr3Co6 cuboctahedra that share corners with three equivalent Co(3)Zr3Co6 cuboctahedra, corners with three equivalent Co(4)Zr3Co6 cuboctahedra, corners with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with six equivalent Co(2)YZr4Co7 cuboctahedra, edges with six equivalent Co(5)Y3Zr3Co6 cuboctahedra,  a faceface with one Co(3)Zr3Co6 cuboctahedra,  a faceface with one Co(4)Zr3Co6 cuboctahedra, faces with nine equivalent Co(1)Y2Zr3Co7 cuboctahedra, and faces with nine equivalent Co(2)YZr4Co7 cuboctahedra. is represented by the CIF file [CIF]
data_YZr2Co9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.848
_cell_length_b   4.848
_cell_length_c   8.474
_cell_angle_alpha   90.000
_cell_angle_beta   73.379
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   162.803
_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
  Y  Y0  1  0.279  0.140  0.581  1.0
  Zr  Zr1  1  0.726  0.863  0.411  1.0
  Zr  Zr2  1  1.000  1.000  0.001  1.0
  Co  Co3  1  0.661  0.580  0.758  1.0
  Co  Co4  1  0.160  0.580  0.758  1.0
  Co  Co5  1  0.661  0.081  0.758  1.0
  Co  Co6  1  0.337  0.420  0.244  1.0
  Co  Co7  1  0.839  0.420  0.244  1.0
  Co  Co8  1  0.337  0.917  0.244  1.0
  Co  Co9  1  0.666  0.333  0.000  1.0
  Co  Co10  1  0.333  0.666  0.001  1.0
  Co  Co11  1  0.001  0.500  0.499  1.0
[/CIF]
.
The material described by YZr2Co9 is Frank-Kasper $\mu$ Phase-derived structured and crystallizes in the trigonal R3m space group. Y(1) is bonded in a 16-coordinate geometry to one Zr(2), three equivalent Zr(1), three equivalent Co(2), three equivalent Co(5), and six equivalent Co(1) atoms. There are two inequivalent Zr sites. In the first Zr site, Zr(1) is bonded in a 15-coordinate geometry to three equivalent Y(1), three equivalent Co(1), three equivalent Co(5), and six equivalent Co(2) atoms. In the second Zr site, Zr(2) is bonded in a distorted hexagonal planar geometry to one Y(1), three equivalent Co(3), three equivalent Co(4), six equivalent Co(1), and six equivalent Co(2) atoms. There are five inequivalent Co sites. In the first Co site, Co(1) is bonded to two equivalent Y(1), one Zr(1), two equivalent Zr(2), one Co(3), one Co(4), one Co(5), and four equivalent Co(1) atoms to form distorted CoY2Zr3Co7 cuboctahedra that share corners with two equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with two equivalent Co(3)Zr3Co6 cuboctahedra, corners with two equivalent Co(4)Zr3Co6 cuboctahedra, corners with four equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with eleven equivalent Co(2)YZr4Co7 cuboctahedra, edges with two equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with two equivalent Co(3)Zr3Co6 cuboctahedra, edges with two equivalent Co(4)Zr3Co6 cuboctahedra, edges with six equivalent Co(2)YZr4Co7 cuboctahedra,  a faceface with one Co(3)Zr3Co6 cuboctahedra,  a faceface with one Co(4)Zr3Co6 cuboctahedra, faces with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, faces with three equivalent Co(2)YZr4Co7 cuboctahedra, and faces with eight equivalent Co(1)Y2Zr3Co7 cuboctahedra. In the second Co site, Co(2) is bonded to one Y(1), two equivalent Zr(1), two equivalent Zr(2), one Co(3), one Co(4), one Co(5), and four equivalent Co(2) atoms to form distorted CoYZr4Co7 cuboctahedra that share corners with two equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with two equivalent Co(3)Zr3Co6 cuboctahedra, corners with two equivalent Co(4)Zr3Co6 cuboctahedra, corners with four equivalent Co(2)YZr4Co7 cuboctahedra, corners with eleven equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with two equivalent Co(2)YZr4Co7 cuboctahedra, edges with two equivalent Co(3)Zr3Co6 cuboctahedra, edges with two equivalent Co(4)Zr3Co6 cuboctahedra, edges with six equivalent Co(1)Y2Zr3Co7 cuboctahedra,  a faceface with one Co(3)Zr3Co6 cuboctahedra,  a faceface with one Co(4)Zr3Co6 cuboctahedra, faces with three equivalent Co(1)Y2Zr3Co7 cuboctahedra, faces with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, and faces with eight equivalent Co(2)YZr4Co7 cuboctahedra. In the third Co site, Co(3) is bonded to three equivalent Zr(2), three equivalent Co(1), and three equivalent Co(2) atoms to form distorted CoZr3Co6 cuboctahedra that share corners with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with three equivalent Co(4)Zr3Co6 cuboctahedra, corners with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with six equivalent Co(2)YZr4Co7 cuboctahedra, corners with six equivalent Co(3)Zr3Co6 cuboctahedra, edges with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with six equivalent Co(2)YZr4Co7 cuboctahedra,  a faceface with one Co(5)Y3Zr3Co6 cuboctahedra, faces with three equivalent Co(1)Y2Zr3Co7 cuboctahedra, faces with three equivalent Co(2)YZr4Co7 cuboctahedra, and faces with three equivalent Co(4)Zr3Co6 cuboctahedra. In the fourth Co site, Co(4) is bonded to three equivalent Zr(2), three equivalent Co(1), and three equivalent Co(2) atoms to form distorted CoZr3Co6 cuboctahedra that share corners with three equivalent Co(5)Y3Zr3Co6 cuboctahedra, corners with three equivalent Co(3)Zr3Co6 cuboctahedra, corners with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with six equivalent Co(2)YZr4Co7 cuboctahedra, corners with six equivalent Co(4)Zr3Co6 cuboctahedra, edges with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, edges with six equivalent Co(2)YZr4Co7 cuboctahedra,  a faceface with one Co(5)Y3Zr3Co6 cuboctahedra, faces with three equivalent Co(1)Y2Zr3Co7 cuboctahedra, faces with three equivalent Co(2)YZr4Co7 cuboctahedra, and faces with three equivalent Co(3)Zr3Co6 cuboctahedra. In the fifth Co site, Co(5) is bonded to three equivalent Y(1), three equivalent Zr(1), three equivalent Co(1), and three equivalent Co(2) atoms to form CoY3Zr3Co6 cuboctahedra that share corners with three equivalent Co(3)Zr3Co6 cuboctahedra, corners with three equivalent Co(4)Zr3Co6 cuboctahedra, corners with six equivalent Co(1)Y2Zr3Co7 cuboctahedra, corners with six equivalent Co(2)YZr4Co7 cuboctahedra, edges with six equivalent Co(5)Y3Zr3Co6 cuboctahedra,  a faceface with one Co(3)Zr3Co6 cuboctahedra,  a faceface with one Co(4)Zr3Co6 cuboctahedra, faces with nine equivalent Co(1)Y2Zr3Co7 cuboctahedra, and faces with nine equivalent Co(2)YZr4Co7 cuboctahedra. is represented by the CIF file [CIF]
data_YZr2Co9
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.848
_cell_length_b   4.848
_cell_length_c   8.474
_cell_angle_alpha   90.000
_cell_angle_beta   73.379
_cell_angle_gamma   120.000
_symmetry_Int_Tables_number   1
_cell_volume   162.803
_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
  Y  Y0  1  0.279  0.140  0.581  1.0
  Zr  Zr1  1  0.726  0.863  0.411  1.0
  Zr  Zr2  1  1.000  1.000  0.001  1.0
  Co  Co3  1  0.661  0.580  0.758  1.0
  Co  Co4  1  0.160  0.580  0.758  1.0
  Co  Co5  1  0.661  0.081  0.758  1.0
  Co  Co6  1  0.337  0.420  0.244  1.0
  Co  Co7  1  0.839  0.420  0.244  1.0
  Co  Co8  1  0.337  0.917  0.244  1.0
  Co  Co9  1  0.666  0.333  0.000  1.0
  Co  Co10  1  0.333  0.666  0.001  1.0
  Co  Co11  1  0.001  0.500  0.499  1.0
[/CIF]
.