The material structure described by Fe5SiAs crystallizes in the monoclinic Cm space group. There are twenty inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted tetrahedral geometry to one Fe(19), one As(2), one As(3), and two equivalent As(4) atoms. In the second Fe site, Fe(2) is bonded in a 4-coordinate geometry to one Fe(13), two equivalent Fe(14), two equivalent Fe(18), two equivalent Si(1), one As(1), and one As(5) atom. In the third Fe site, Fe(3) is bonded in a 13-coordinate geometry to one Fe(11), one Fe(17), one Fe(7), two equivalent Fe(12), two equivalent Fe(15), two equivalent Fe(8), two equivalent Si(2), one As(1), and one As(3) atom. In the fourth Fe site, Fe(4) is bonded in a 13-coordinate geometry to one Fe(11), one Fe(18), one Fe(7), two equivalent Fe(12), two equivalent Fe(15), two equivalent Fe(8), two equivalent Si(2), one As(1), and one As(4) atom. In the fifth Fe site, Fe(5) is bonded in a 4-coordinate geometry to one Fe(13), one Fe(19), two equivalent Fe(14), two equivalent Fe(16), two equivalent Si(3), one As(2), and one As(5) atom. In the sixth Fe site, Fe(6) is bonded in a 13-coordinate geometry to one Fe(13), one Fe(20), one Fe(9), two equivalent Fe(10), two equivalent Fe(14), two equivalent Fe(16), one Si(1), two equivalent Si(3), and one As(2) atom. In the seventh Fe site, Fe(7) is bonded in a 4-coordinate geometry to one Fe(3), two equivalent Fe(18), two equivalent Fe(4), two equivalent Si(2), one As(1), and one As(5) atom. In the eighth Fe site, Fe(8) is bonded in a 4-coordinate geometry to one Fe(3), two equivalent Fe(18), two equivalent Fe(4), one Si(1), two equivalent Si(2), and one As(1) atom. In the ninth Fe site, Fe(9) is bonded in a 4-coordinate geometry to one Fe(13), one Fe(19), two equivalent Fe(6), two equivalent Si(3), one As(2), and one As(3) atom. In the tenth Fe site, Fe(10) is bonded in a 4-coordinate geometry to one Fe(14), one Fe(19), two equivalent Fe(6), two equivalent Si(3), one As(2), and one As(4) atom. In the eleventh Fe site, Fe(11) is bonded in a 3-coordinate geometry to one Fe(19), one Fe(3), two equivalent Fe(15), two equivalent Fe(4), one As(1), one As(3), and two equivalent As(4) atoms. In the twelfth Fe site, Fe(12) is bonded in a 3-coordinate geometry to one Fe(3), two equivalent Fe(15), two equivalent Fe(4), one As(1), one As(3), and two equivalent As(4) atoms. In the thirteenth Fe site, Fe(13) is bonded in a 12-coordinate geometry to one Fe(17), one Fe(2), one Fe(5), one Fe(9), two equivalent Fe(16), two equivalent Fe(6), two equivalent Si(1), one As(2), and one As(5) atom. In the fourteenth Fe site, Fe(14) is bonded in a 12-coordinate geometry to one Fe(10), one Fe(18), one Fe(2), one Fe(5), two equivalent Fe(16), two equivalent Fe(6), two equivalent Si(1), one As(2), and one As(5) atom. In the fifteenth Fe site, Fe(15) is bonded in a 10-coordinate geometry to one Fe(11), one Fe(3), two equivalent Fe(12), two equivalent Fe(4), one Si(2), one As(3), and two equivalent As(4) atoms. In the sixteenth Fe site, Fe(16) is bonded in a 10-coordinate geometry to one Fe(13), one Fe(5), two equivalent Fe(14), two equivalent Fe(6), one Si(3), two equivalent Si(1), and one As(5) atom. In the seventeenth Fe site, Fe(17) is bonded in a distorted single-bond geometry to one Fe(13), one Fe(3), two equivalent Si(1), two equivalent Si(2), and one As(5) atom. In the eighteenth Fe site, Fe(18) is bonded in a 11-coordinate geometry to one Fe(14), one Fe(2), one Fe(4), one Fe(7), two equivalent Fe(8), two equivalent Si(1), two equivalent Si(2), and one As(5) atom. In the nineteenth Fe site, Fe(19) is bonded in a 11-coordinate geometry to one Fe(1), one Fe(11), one Fe(5), one Fe(9), two equivalent Fe(10), two equivalent Si(3), one As(3), and two equivalent As(4) atoms. In the twentieth Fe site, Fe(20) is bonded in a 1-coordinate geometry to one Fe(6), two equivalent Si(3), one As(3), and two equivalent As(4) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to one Fe(13), one Fe(17), one Fe(2), one Fe(6), one Fe(8), two equivalent Fe(14), two equivalent Fe(16), and two equivalent Fe(18) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Fe(15), one Fe(17), one Fe(3), one Fe(7), two equivalent Fe(18), two equivalent Fe(4), and two equivalent Fe(8) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Fe(16), one Fe(19), one Fe(5), one Fe(9), two equivalent Fe(10), two equivalent Fe(20), and two equivalent Fe(6) atoms. There are five inequivalent As sites. In the first As site, As(1) is bonded in a 10-coordinate geometry to one Fe(11), one Fe(2), one Fe(3), one Fe(7), two equivalent Fe(12), two equivalent Fe(4), and two equivalent Fe(8) atoms. In the second As site, As(2) is bonded in a 10-coordinate geometry to one Fe(1), one Fe(13), one Fe(5), one Fe(9), two equivalent Fe(10), two equivalent Fe(14), and two equivalent Fe(6) atoms. In the third As site, As(3) is bonded in a 11-coordinate geometry to one Fe(1), one Fe(11), one Fe(19), one Fe(3), one Fe(9), two equivalent Fe(12), two equivalent Fe(15), and two equivalent Fe(20) atoms. In the fourth As site, As(4) is bonded in a 11-coordinate geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(19), one Fe(4), two equivalent Fe(12), two equivalent Fe(15), and two equivalent Fe(20) atoms. In the fifth As site, As(5) is bonded in a 10-coordinate geometry to one Fe(13), one Fe(17), one Fe(2), one Fe(5), one Fe(7), two equivalent Fe(14), two equivalent Fe(16), and two equivalent Fe(18) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe5SiAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.840
_cell_length_b   6.840
_cell_length_c   12.466
_cell_angle_alpha   89.777
_cell_angle_beta   89.777
_cell_angle_gamma   120.030
_symmetry_Int_Tables_number   1
_cell_volume   504.965
_cell_formula_units_Z   6
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
  Fe  Fe0  1  1.000  1.000  0.448  1.0
  Fe  Fe1  1  0.997  0.997  0.952  1.0
  Fe  Fe2  1  0.628  0.628  0.716  1.0
  Fe  Fe3  1  0.999  0.369  0.715  1.0
  Fe  Fe4  1  0.369  0.999  0.715  1.0
  Fe  Fe5  1  0.372  0.372  0.211  1.0
  Fe  Fe6  1  0.001  0.635  0.209  1.0
  Fe  Fe7  1  0.635  0.001  0.209  1.0
  Fe  Fe8  1  0.315  0.315  0.824  1.0
  Fe  Fe9  1  0.996  0.681  0.826  1.0
  Fe  Fe10  1  0.681  0.996  0.826  1.0
  Fe  Fe11  1  0.685  0.685  0.322  1.0
  Fe  Fe12  1  0.000  0.317  0.322  1.0
  Fe  Fe13  1  0.317  0.000  0.322  1.0
  Fe  Fe14  1  0.279  0.279  0.619  1.0
  Fe  Fe15  1  0.999  0.721  0.619  1.0
  Fe  Fe16  1  0.721  0.999  0.619  1.0
  Fe  Fe17  1  0.727  0.727  0.116  1.0
  Fe  Fe18  1  0.995  0.290  0.116  1.0
  Fe  Fe19  1  0.290  0.995  0.116  1.0
  Fe  Fe20  1  0.668  0.333  0.599  1.0
  Fe  Fe21  1  0.333  0.668  0.599  1.0
  Fe  Fe22  1  0.337  0.669  0.089  1.0
  Fe  Fe23  1  0.669  0.337  0.089  1.0
  Fe  Fe24  1  0.644  0.644  0.917  1.0
  Fe  Fe25  1  0.988  0.356  0.916  1.0
  Fe  Fe26  1  0.356  0.988  0.916  1.0
  Fe  Fe27  1  0.362  0.362  0.409  1.0
  Fe  Fe28  1  0.999  0.638  0.409  1.0
  Fe  Fe29  1  0.638  0.999  0.409  1.0
  Si  Si30  1  0.001  0.667  0.015  1.0
  Si  Si31  1  0.667  0.001  0.015  1.0
  Si  Si32  1  0.665  0.331  0.797  1.0
  Si  Si33  1  0.331  0.665  0.797  1.0
  Si  Si34  1  0.334  0.668  0.287  1.0
  Si  Si35  1  0.668  0.334  0.287  1.0
  As  As36  1  1.000  1.000  0.753  1.0
  As  As37  1  0.003  0.003  0.249  1.0
  As  As38  1  0.665  0.665  0.516  1.0
  As  As39  1  0.000  0.335  0.515  1.0
  As  As40  1  0.335  0.000  0.515  1.0
  As  As41  1  0.331  0.331  0.015  1.0
[/CIF]
.
The material structure described by Fe5SiAs crystallizes in the monoclinic Cm space group. There are twenty inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in a distorted tetrahedral geometry to one Fe(19), one As(2), one As(3), and two equivalent As(4) atoms. In the second Fe site, Fe(2) is bonded in a 4-coordinate geometry to one Fe(13), two equivalent Fe(14), two equivalent Fe(18), two equivalent Si(1), one As(1), and one As(5) atom. In the third Fe site, Fe(3) is bonded in a 13-coordinate geometry to one Fe(11), one Fe(17), one Fe(7), two equivalent Fe(12), two equivalent Fe(15), two equivalent Fe(8), two equivalent Si(2), one As(1), and one As(3) atom. In the fourth Fe site, Fe(4) is bonded in a 13-coordinate geometry to one Fe(11), one Fe(18), one Fe(7), two equivalent Fe(12), two equivalent Fe(15), two equivalent Fe(8), two equivalent Si(2), one As(1), and one As(4) atom. In the fifth Fe site, Fe(5) is bonded in a 4-coordinate geometry to one Fe(13), one Fe(19), two equivalent Fe(14), two equivalent Fe(16), two equivalent Si(3), one As(2), and one As(5) atom. In the sixth Fe site, Fe(6) is bonded in a 13-coordinate geometry to one Fe(13), one Fe(20), one Fe(9), two equivalent Fe(10), two equivalent Fe(14), two equivalent Fe(16), one Si(1), two equivalent Si(3), and one As(2) atom. In the seventh Fe site, Fe(7) is bonded in a 4-coordinate geometry to one Fe(3), two equivalent Fe(18), two equivalent Fe(4), two equivalent Si(2), one As(1), and one As(5) atom. In the eighth Fe site, Fe(8) is bonded in a 4-coordinate geometry to one Fe(3), two equivalent Fe(18), two equivalent Fe(4), one Si(1), two equivalent Si(2), and one As(1) atom. In the ninth Fe site, Fe(9) is bonded in a 4-coordinate geometry to one Fe(13), one Fe(19), two equivalent Fe(6), two equivalent Si(3), one As(2), and one As(3) atom. In the tenth Fe site, Fe(10) is bonded in a 4-coordinate geometry to one Fe(14), one Fe(19), two equivalent Fe(6), two equivalent Si(3), one As(2), and one As(4) atom. In the eleventh Fe site, Fe(11) is bonded in a 3-coordinate geometry to one Fe(19), one Fe(3), two equivalent Fe(15), two equivalent Fe(4), one As(1), one As(3), and two equivalent As(4) atoms. In the twelfth Fe site, Fe(12) is bonded in a 3-coordinate geometry to one Fe(3), two equivalent Fe(15), two equivalent Fe(4), one As(1), one As(3), and two equivalent As(4) atoms. In the thirteenth Fe site, Fe(13) is bonded in a 12-coordinate geometry to one Fe(17), one Fe(2), one Fe(5), one Fe(9), two equivalent Fe(16), two equivalent Fe(6), two equivalent Si(1), one As(2), and one As(5) atom. In the fourteenth Fe site, Fe(14) is bonded in a 12-coordinate geometry to one Fe(10), one Fe(18), one Fe(2), one Fe(5), two equivalent Fe(16), two equivalent Fe(6), two equivalent Si(1), one As(2), and one As(5) atom. In the fifteenth Fe site, Fe(15) is bonded in a 10-coordinate geometry to one Fe(11), one Fe(3), two equivalent Fe(12), two equivalent Fe(4), one Si(2), one As(3), and two equivalent As(4) atoms. In the sixteenth Fe site, Fe(16) is bonded in a 10-coordinate geometry to one Fe(13), one Fe(5), two equivalent Fe(14), two equivalent Fe(6), one Si(3), two equivalent Si(1), and one As(5) atom. In the seventeenth Fe site, Fe(17) is bonded in a distorted single-bond geometry to one Fe(13), one Fe(3), two equivalent Si(1), two equivalent Si(2), and one As(5) atom. In the eighteenth Fe site, Fe(18) is bonded in a 11-coordinate geometry to one Fe(14), one Fe(2), one Fe(4), one Fe(7), two equivalent Fe(8), two equivalent Si(1), two equivalent Si(2), and one As(5) atom. In the nineteenth Fe site, Fe(19) is bonded in a 11-coordinate geometry to one Fe(1), one Fe(11), one Fe(5), one Fe(9), two equivalent Fe(10), two equivalent Si(3), one As(3), and two equivalent As(4) atoms. In the twentieth Fe site, Fe(20) is bonded in a 1-coordinate geometry to one Fe(6), two equivalent Si(3), one As(3), and two equivalent As(4) atoms. There are three inequivalent Si sites. In the first Si site, Si(1) is bonded in a 11-coordinate geometry to one Fe(13), one Fe(17), one Fe(2), one Fe(6), one Fe(8), two equivalent Fe(14), two equivalent Fe(16), and two equivalent Fe(18) atoms. In the second Si site, Si(2) is bonded in a 10-coordinate geometry to one Fe(15), one Fe(17), one Fe(3), one Fe(7), two equivalent Fe(18), two equivalent Fe(4), and two equivalent Fe(8) atoms. In the third Si site, Si(3) is bonded in a 10-coordinate geometry to one Fe(16), one Fe(19), one Fe(5), one Fe(9), two equivalent Fe(10), two equivalent Fe(20), and two equivalent Fe(6) atoms. There are five inequivalent As sites. In the first As site, As(1) is bonded in a 10-coordinate geometry to one Fe(11), one Fe(2), one Fe(3), one Fe(7), two equivalent Fe(12), two equivalent Fe(4), and two equivalent Fe(8) atoms. In the second As site, As(2) is bonded in a 10-coordinate geometry to one Fe(1), one Fe(13), one Fe(5), one Fe(9), two equivalent Fe(10), two equivalent Fe(14), and two equivalent Fe(6) atoms. In the third As site, As(3) is bonded in a 11-coordinate geometry to one Fe(1), one Fe(11), one Fe(19), one Fe(3), one Fe(9), two equivalent Fe(12), two equivalent Fe(15), and two equivalent Fe(20) atoms. In the fourth As site, As(4) is bonded in a 11-coordinate geometry to one Fe(1), one Fe(10), one Fe(11), one Fe(19), one Fe(4), two equivalent Fe(12), two equivalent Fe(15), and two equivalent Fe(20) atoms. In the fifth As site, As(5) is bonded in a 10-coordinate geometry to one Fe(13), one Fe(17), one Fe(2), one Fe(5), one Fe(7), two equivalent Fe(14), two equivalent Fe(16), and two equivalent Fe(18) atoms. is represented by the Crystallographic Information File (CIF) [CIF]
data_Fe5SiAs
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   6.840
_cell_length_b   6.840
_cell_length_c   12.466
_cell_angle_alpha   89.777
_cell_angle_beta   89.777
_cell_angle_gamma   120.030
_symmetry_Int_Tables_number   1
_cell_volume   504.965
_cell_formula_units_Z   6
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
  Fe  Fe0  1  1.000  1.000  0.448  1.0
  Fe  Fe1  1  0.997  0.997  0.952  1.0
  Fe  Fe2  1  0.628  0.628  0.716  1.0
  Fe  Fe3  1  0.999  0.369  0.715  1.0
  Fe  Fe4  1  0.369  0.999  0.715  1.0
  Fe  Fe5  1  0.372  0.372  0.211  1.0
  Fe  Fe6  1  0.001  0.635  0.209  1.0
  Fe  Fe7  1  0.635  0.001  0.209  1.0
  Fe  Fe8  1  0.315  0.315  0.824  1.0
  Fe  Fe9  1  0.996  0.681  0.826  1.0
  Fe  Fe10  1  0.681  0.996  0.826  1.0
  Fe  Fe11  1  0.685  0.685  0.322  1.0
  Fe  Fe12  1  0.000  0.317  0.322  1.0
  Fe  Fe13  1  0.317  0.000  0.322  1.0
  Fe  Fe14  1  0.279  0.279  0.619  1.0
  Fe  Fe15  1  0.999  0.721  0.619  1.0
  Fe  Fe16  1  0.721  0.999  0.619  1.0
  Fe  Fe17  1  0.727  0.727  0.116  1.0
  Fe  Fe18  1  0.995  0.290  0.116  1.0
  Fe  Fe19  1  0.290  0.995  0.116  1.0
  Fe  Fe20  1  0.668  0.333  0.599  1.0
  Fe  Fe21  1  0.333  0.668  0.599  1.0
  Fe  Fe22  1  0.337  0.669  0.089  1.0
  Fe  Fe23  1  0.669  0.337  0.089  1.0
  Fe  Fe24  1  0.644  0.644  0.917  1.0
  Fe  Fe25  1  0.988  0.356  0.916  1.0
  Fe  Fe26  1  0.356  0.988  0.916  1.0
  Fe  Fe27  1  0.362  0.362  0.409  1.0
  Fe  Fe28  1  0.999  0.638  0.409  1.0
  Fe  Fe29  1  0.638  0.999  0.409  1.0
  Si  Si30  1  0.001  0.667  0.015  1.0
  Si  Si31  1  0.667  0.001  0.015  1.0
  Si  Si32  1  0.665  0.331  0.797  1.0
  Si  Si33  1  0.331  0.665  0.797  1.0
  Si  Si34  1  0.334  0.668  0.287  1.0
  Si  Si35  1  0.668  0.334  0.287  1.0
  As  As36  1  1.000  1.000  0.753  1.0
  As  As37  1  0.003  0.003  0.249  1.0
  As  As38  1  0.665  0.665  0.516  1.0
  As  As39  1  0.000  0.335  0.515  1.0
  As  As40  1  0.335  0.000  0.515  1.0
  As  As41  1  0.331  0.331  0.015  1.0
[/CIF]
.