The crystal structure described by SrNd7Fe8(AsO)8 crystallizes in the tetragonal I4mm space group. Sr(1) is bonded in a 4-coordinate geometry to four equivalent As(1) and four equivalent O(2) atoms. There are three inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 4-coordinate geometry to one As(2), one As(4), two equivalent As(3), two equivalent O(1), and two equivalent O(2) atoms. In the second Nd site, Nd(2) is bonded in a 4-coordinate geometry to four equivalent As(1), two equivalent O(1), and two equivalent O(2) atoms. In the third Nd site, Nd(3) is bonded in a 4-coordinate geometry to four equivalent As(1) and four equivalent O(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one As(2), one As(3), and two equivalent As(1) atoms to form a mixture of distorted edge and corner-sharing FeAs4 tetrahedra. In the second Fe site, Fe(2) is bonded to one As(3), one As(4), and two equivalent As(1) atoms to form a mixture of distorted edge and corner-sharing FeAs4 tetrahedra. There are four inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to one Sr(1), one Nd(3), two equivalent Nd(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to four equivalent Nd(1) and four equivalent Fe(1) atoms. In the third As site, As(3) is bonded in a 8-coordinate geometry to four equivalent Nd(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to four equivalent Nd(1) and four equivalent Fe(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Nd(2), one Nd(3), and two equivalent Nd(1) atoms to form ONd4 tetrahedra that share corners with two equivalent O(1)Nd4 tetrahedra, corners with two equivalent O(2)SrNd3 tetrahedra, edges with two equivalent O(1)Nd4 tetrahedra, and edges with two equivalent O(2)SrNd3 tetrahedra. In the second O site, O(2) is bonded to one Sr(1), one Nd(2), and two equivalent Nd(1) atoms to form OSrNd3 tetrahedra that share corners with two equivalent O(1)Nd4 tetrahedra, corners with two equivalent O(2)SrNd3 tetrahedra, edges with two equivalent O(1)Nd4 tetrahedra, and edges with two equivalent O(2)SrNd3 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_SrNd7Fe8(AsO)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.017
_cell_length_b   11.017
_cell_length_c   11.017
_cell_angle_alpha   136.337
_cell_angle_beta   136.337
_cell_angle_gamma   63.459
_symmetry_Int_Tables_number   1
_cell_volume   629.184
_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
  Sr  Sr0  1  0.309  0.309  0.000  1.0
  Nd  Nd1  1  0.187  0.187  0.502  1.0
  Nd  Nd2  1  0.685  0.187  0.000  1.0
  Nd  Nd3  1  0.314  0.814  0.500  1.0
  Nd  Nd4  1  0.813  0.813  0.000  1.0
  Nd  Nd5  1  0.187  0.685  0.000  1.0
  Nd  Nd6  1  0.685  0.685  0.498  1.0
  Nd  Nd7  1  0.814  0.314  0.500  1.0
  Fe  Fe8  1  0.624  0.375  0.750  1.0
  Fe  Fe9  1  0.125  0.375  0.250  1.0
  Fe  Fe10  1  0.874  0.624  0.250  1.0
  Fe  Fe11  1  0.375  0.624  0.750  1.0
  Fe  Fe12  1  0.624  0.874  0.250  1.0
  Fe  Fe13  1  0.125  0.875  0.750  1.0
  Fe  Fe14  1  0.875  0.125  0.750  1.0
  Fe  Fe15  1  0.375  0.125  0.250  1.0
  As  As16  1  0.962  0.463  0.000  1.0
  As  As17  1  0.463  0.463  0.501  1.0
  As  As18  1  0.536  0.536  0.000  1.0
  As  As19  1  0.038  0.538  0.500  1.0
  As  As20  1  0.962  0.962  0.499  1.0
  As  As21  1  0.463  0.962  0.000  1.0
  As  As22  1  0.538  0.038  0.500  1.0
  As  As23  1  0.037  0.037  0.000  1.0
  O  O24  1  0.122  0.874  0.248  1.0
  O  O25  1  0.627  0.874  0.752  1.0
  O  O26  1  0.378  0.119  0.741  1.0
  O  O27  1  0.874  0.122  0.248  1.0
  O  O28  1  0.119  0.378  0.741  1.0
  O  O29  1  0.637  0.378  0.259  1.0
  O  O30  1  0.378  0.637  0.259  1.0
  O  O31  1  0.874  0.627  0.752  1.0
[/CIF]
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The crystal structure described by SrNd7Fe8(AsO)8 crystallizes in the tetragonal I4mm space group. Sr(1) is bonded in a 4-coordinate geometry to four equivalent As(1) and four equivalent O(2) atoms. There are three inequivalent Nd sites. In the first Nd site, Nd(1) is bonded in a 4-coordinate geometry to one As(2), one As(4), two equivalent As(3), two equivalent O(1), and two equivalent O(2) atoms. In the second Nd site, Nd(2) is bonded in a 4-coordinate geometry to four equivalent As(1), two equivalent O(1), and two equivalent O(2) atoms. In the third Nd site, Nd(3) is bonded in a 4-coordinate geometry to four equivalent As(1) and four equivalent O(1) atoms. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one As(2), one As(3), and two equivalent As(1) atoms to form a mixture of distorted edge and corner-sharing FeAs4 tetrahedra. In the second Fe site, Fe(2) is bonded to one As(3), one As(4), and two equivalent As(1) atoms to form a mixture of distorted edge and corner-sharing FeAs4 tetrahedra. There are four inequivalent As sites. In the first As site, As(1) is bonded in a 8-coordinate geometry to one Sr(1), one Nd(3), two equivalent Nd(2), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the second As site, As(2) is bonded in a 8-coordinate geometry to four equivalent Nd(1) and four equivalent Fe(1) atoms. In the third As site, As(3) is bonded in a 8-coordinate geometry to four equivalent Nd(1), two equivalent Fe(1), and two equivalent Fe(2) atoms. In the fourth As site, As(4) is bonded in a 8-coordinate geometry to four equivalent Nd(1) and four equivalent Fe(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Nd(2), one Nd(3), and two equivalent Nd(1) atoms to form ONd4 tetrahedra that share corners with two equivalent O(1)Nd4 tetrahedra, corners with two equivalent O(2)SrNd3 tetrahedra, edges with two equivalent O(1)Nd4 tetrahedra, and edges with two equivalent O(2)SrNd3 tetrahedra. In the second O site, O(2) is bonded to one Sr(1), one Nd(2), and two equivalent Nd(1) atoms to form OSrNd3 tetrahedra that share corners with two equivalent O(1)Nd4 tetrahedra, corners with two equivalent O(2)SrNd3 tetrahedra, edges with two equivalent O(1)Nd4 tetrahedra, and edges with two equivalent O(2)SrNd3 tetrahedra. is represented by the Crystallographic Information File (CIF) [CIF]
data_SrNd7Fe8(AsO)8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   11.017
_cell_length_b   11.017
_cell_length_c   11.017
_cell_angle_alpha   136.337
_cell_angle_beta   136.337
_cell_angle_gamma   63.459
_symmetry_Int_Tables_number   1
_cell_volume   629.184
_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
  Sr  Sr0  1  0.309  0.309  0.000  1.0
  Nd  Nd1  1  0.187  0.187  0.502  1.0
  Nd  Nd2  1  0.685  0.187  0.000  1.0
  Nd  Nd3  1  0.314  0.814  0.500  1.0
  Nd  Nd4  1  0.813  0.813  0.000  1.0
  Nd  Nd5  1  0.187  0.685  0.000  1.0
  Nd  Nd6  1  0.685  0.685  0.498  1.0
  Nd  Nd7  1  0.814  0.314  0.500  1.0
  Fe  Fe8  1  0.624  0.375  0.750  1.0
  Fe  Fe9  1  0.125  0.375  0.250  1.0
  Fe  Fe10  1  0.874  0.624  0.250  1.0
  Fe  Fe11  1  0.375  0.624  0.750  1.0
  Fe  Fe12  1  0.624  0.874  0.250  1.0
  Fe  Fe13  1  0.125  0.875  0.750  1.0
  Fe  Fe14  1  0.875  0.125  0.750  1.0
  Fe  Fe15  1  0.375  0.125  0.250  1.0
  As  As16  1  0.962  0.463  0.000  1.0
  As  As17  1  0.463  0.463  0.501  1.0
  As  As18  1  0.536  0.536  0.000  1.0
  As  As19  1  0.038  0.538  0.500  1.0
  As  As20  1  0.962  0.962  0.499  1.0
  As  As21  1  0.463  0.962  0.000  1.0
  As  As22  1  0.538  0.038  0.500  1.0
  As  As23  1  0.037  0.037  0.000  1.0
  O  O24  1  0.122  0.874  0.248  1.0
  O  O25  1  0.627  0.874  0.752  1.0
  O  O26  1  0.378  0.119  0.741  1.0
  O  O27  1  0.874  0.122  0.248  1.0
  O  O28  1  0.119  0.378  0.741  1.0
  O  O29  1  0.637  0.378  0.259  1.0
  O  O30  1  0.378  0.637  0.259  1.0
  O  O31  1  0.874  0.627  0.752  1.0
[/CIF]
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