The compound described by Sr5Nb5O16 crystallizes in the orthorhombic Pmn2_1 space group. There are five inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to three equivalent O(10) and three equivalent O(12) atoms. In the second Sr site, Sr(2) is bonded to one O(13), one O(14), two equivalent O(15), two equivalent O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms to form SrO12 cuboctahedra that share corners with two equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with two equivalent Nb(5)O6 octahedra, and faces with four equivalent Nb(3)O6 octahedra. In the third Sr site, Sr(3) is bonded in a 11-coordinate geometry to one O(15), two equivalent O(11), two equivalent O(13), two equivalent O(6), two equivalent O(8), and two equivalent O(9) atoms. In the fourth Sr site, Sr(4) is bonded in a 12-coordinate geometry to one O(15), one O(16), two equivalent O(14), two equivalent O(2), two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms. In the fifth Sr site, Sr(5) is bonded in a 7-coordinate geometry to one O(16), three equivalent O(1), and three equivalent O(3) atoms. There are five inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(16) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 6-32°. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), one O(5), one O(7), and two equivalent O(14) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-32°. In the third Nb site, Nb(3) is bonded to one O(5), one O(6), one O(7), one O(9), and two equivalent O(15) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra, and faces with four equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-18°. In the fourth Nb site, Nb(4) is bonded in a rectangular see-saw-like geometry to one O(10), one O(11), one O(12), and one O(8) atom. In the fifth Nb site, Nb(5) is bonded to one O(11), one O(6), one O(8), one O(9), and two equivalent O(13) atoms to form NbO6 octahedra that share corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra, and faces with two equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-15°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to three equivalent Sr(5) and one Nb(1) atom. In the second O site, O(2) is bonded to two equivalent Sr(4), one Nb(1), and one Nb(2) atom to form distorted OSr2Nb2 tetrahedra that share corners with two equivalent O(14)Sr3Nb2 square pyramids,  a cornercorner with one O(3)Sr3Nb tetrahedra, corners with two equivalent O(2)Sr2Nb2 tetrahedra, and edges with two equivalent O(14)Sr3Nb2 square pyramids. In the third O site, O(3) is bonded to three equivalent Sr(5) and one Nb(1) atom to form OSr3Nb tetrahedra that share  a cornercorner with one O(2)Sr2Nb2 tetrahedra and corners with six equivalent O(3)Sr3Nb tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Sr(4), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), one Nb(2), and one Nb(3) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), one Nb(3), and one Nb(5) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), one Nb(2), and one Nb(3) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(3), one Nb(4), and one Nb(5) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), one Nb(3), and one Nb(5) atom. In the tenth O site, O(10) is bonded to three equivalent Sr(1) and one Nb(4) atom to form OSr3Nb tetrahedra that share corners with six equivalent O(10)Sr3Nb tetrahedra,  a cornercorner with one O(11)Sr2Nb2 trigonal pyramid, corners with two equivalent O(12)Sr3Nb trigonal pyramids, and edges with four equivalent O(12)Sr3Nb trigonal pyramids. In the eleventh O site, O(11) is bonded to two equivalent Sr(3), one Nb(4), and one Nb(5) atom to form distorted OSr2Nb2 trigonal pyramids that share  a cornercorner with one O(10)Sr3Nb tetrahedra,  a cornercorner with one O(12)Sr3Nb trigonal pyramid, and corners with two equivalent O(11)Sr2Nb2 trigonal pyramids. In the twelfth O site, O(12) is bonded to three equivalent Sr(1) and one Nb(4) atom to form distorted OSr3Nb trigonal pyramids that share corners with two equivalent O(10)Sr3Nb tetrahedra,  a cornercorner with one O(11)Sr2Nb2 trigonal pyramid, corners with six equivalent O(12)Sr3Nb trigonal pyramids, and edges with four equivalent O(10)Sr3Nb tetrahedra. In the thirteenth O site, O(13) is bonded in a distorted linear geometry to one Sr(2), two equivalent Sr(3), and two equivalent Nb(5) atoms. In the fourteenth O site, O(14) is bonded to one Sr(2), two equivalent Sr(4), and two equivalent Nb(2) atoms to form distorted OSr3Nb2 square pyramids that share corners with four equivalent O(14)Sr3Nb2 square pyramids, corners with two equivalent O(2)Sr2Nb2 tetrahedra, and edges with two equivalent O(2)Sr2Nb2 tetrahedra. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Sr(3), one Sr(4), two equivalent Sr(2), and two equivalent Nb(3) atoms. In the sixteenth O site, O(16) is bonded in a 4-coordinate geometry to one Sr(4), one Sr(5), and two equivalent Nb(1) atoms. is represented by the CIF card [CIF]
data_Sr5Nb5O16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.029
_cell_length_b   5.714
_cell_length_c   32.948
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   758.545
_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
  Sr  Sr0  1  0.000  0.047  0.530  1.0
  Sr  Sr1  1  0.000  0.068  0.751  1.0
  Sr  Sr2  1  0.000  0.575  0.663  1.0
  Sr  Sr3  1  0.000  0.560  0.841  1.0
  Sr  Sr4  1  0.000  0.130  0.967  1.0
  Sr  Sr5  1  0.500  0.630  0.033  1.0
  Sr  Sr6  1  0.500  0.060  0.159  1.0
  Sr  Sr7  1  0.500  0.568  0.249  1.0
  Sr  Sr8  1  0.500  0.075  0.337  1.0
  Sr  Sr9  1  0.500  0.547  0.470  1.0
  Nb  Nb10  1  0.000  0.099  0.073  1.0
  Nb  Nb11  1  0.000  0.571  0.160  1.0
  Nb  Nb12  1  0.000  0.069  0.249  1.0
  Nb  Nb13  1  0.000  0.059  0.425  1.0
  Nb  Nb14  1  0.000  0.567  0.339  1.0
  Nb  Nb15  1  0.500  0.559  0.575  1.0
  Nb  Nb16  1  0.500  0.067  0.661  1.0
  Nb  Nb17  1  0.500  0.569  0.751  1.0
  Nb  Nb18  1  0.500  0.071  0.840  1.0
  Nb  Nb19  1  0.500  0.599  0.927  1.0
  O  O20  1  0.000  0.363  0.040  1.0
  O  O21  1  0.000  0.273  0.129  1.0
  O  O22  1  0.000  0.881  0.030  1.0
  O  O23  1  0.000  0.796  0.118  1.0
  O  O24  1  0.000  0.353  0.213  1.0
  O  O25  1  0.000  0.295  0.297  1.0
  O  O26  1  0.000  0.844  0.202  1.0
  O  O27  1  0.000  0.322  0.380  1.0
  O  O28  1  0.000  0.789  0.287  1.0
  O  O29  1  0.000  0.287  0.466  1.0
  O  O30  1  0.000  0.858  0.372  1.0
  O  O31  1  0.000  0.806  0.461  1.0
  O  O32  1  0.000  0.070  0.665  1.0
  O  O33  1  0.000  0.060  0.834  1.0
  O  O34  1  0.000  0.568  0.751  1.0
  O  O35  1  0.000  0.570  0.919  1.0
  O  O36  1  0.500  0.070  0.081  1.0
  O  O37  1  0.500  0.560  0.166  1.0
  O  O38  1  0.500  0.068  0.249  1.0
  O  O39  1  0.500  0.570  0.335  1.0
  O  O40  1  0.500  0.306  0.539  1.0
  O  O41  1  0.500  0.787  0.534  1.0
  O  O42  1  0.500  0.289  0.713  1.0
  O  O43  1  0.500  0.822  0.620  1.0
  O  O44  1  0.500  0.358  0.628  1.0
  O  O45  1  0.500  0.795  0.703  1.0
  O  O46  1  0.500  0.853  0.787  1.0
  O  O47  1  0.500  0.344  0.798  1.0
  O  O48  1  0.500  0.296  0.882  1.0
  O  O49  1  0.500  0.773  0.871  1.0
  O  O50  1  0.500  0.381  0.970  1.0
  O  O51  1  0.500  0.863  0.960  1.0
[/CIF]
.
The compound described by Sr5Nb5O16 crystallizes in the orthorhombic Pmn2_1 space group. There are five inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 6-coordinate geometry to three equivalent O(10) and three equivalent O(12) atoms. In the second Sr site, Sr(2) is bonded to one O(13), one O(14), two equivalent O(15), two equivalent O(5), two equivalent O(6), two equivalent O(7), and two equivalent O(9) atoms to form SrO12 cuboctahedra that share corners with two equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Sr(2)O12 cuboctahedra, faces with two equivalent Nb(2)O6 octahedra, faces with two equivalent Nb(5)O6 octahedra, and faces with four equivalent Nb(3)O6 octahedra. In the third Sr site, Sr(3) is bonded in a 11-coordinate geometry to one O(15), two equivalent O(11), two equivalent O(13), two equivalent O(6), two equivalent O(8), and two equivalent O(9) atoms. In the fourth Sr site, Sr(4) is bonded in a 12-coordinate geometry to one O(15), one O(16), two equivalent O(14), two equivalent O(2), two equivalent O(4), two equivalent O(5), and two equivalent O(7) atoms. In the fifth Sr site, Sr(5) is bonded in a 7-coordinate geometry to one O(16), three equivalent O(1), and three equivalent O(3) atoms. There are five inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(4), and two equivalent O(16) atoms to form distorted corner-sharing NbO6 octahedra. The corner-sharing octahedral tilt angles range from 6-32°. In the second Nb site, Nb(2) is bonded to one O(2), one O(4), one O(5), one O(7), and two equivalent O(14) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, and faces with two equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-32°. In the third Nb site, Nb(3) is bonded to one O(5), one O(6), one O(7), one O(9), and two equivalent O(15) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra, corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra, and faces with four equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 1-18°. In the fourth Nb site, Nb(4) is bonded in a rectangular see-saw-like geometry to one O(10), one O(11), one O(12), and one O(8) atom. In the fifth Nb site, Nb(5) is bonded to one O(11), one O(6), one O(8), one O(9), and two equivalent O(13) atoms to form NbO6 octahedra that share corners with two equivalent Nb(3)O6 octahedra, corners with two equivalent Nb(5)O6 octahedra, and faces with two equivalent Sr(2)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 8-15°. There are sixteen inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to three equivalent Sr(5) and one Nb(1) atom. In the second O site, O(2) is bonded to two equivalent Sr(4), one Nb(1), and one Nb(2) atom to form distorted OSr2Nb2 tetrahedra that share corners with two equivalent O(14)Sr3Nb2 square pyramids,  a cornercorner with one O(3)Sr3Nb tetrahedra, corners with two equivalent O(2)Sr2Nb2 tetrahedra, and edges with two equivalent O(14)Sr3Nb2 square pyramids. In the third O site, O(3) is bonded to three equivalent Sr(5) and one Nb(1) atom to form OSr3Nb tetrahedra that share  a cornercorner with one O(2)Sr2Nb2 tetrahedra and corners with six equivalent O(3)Sr3Nb tetrahedra. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to two equivalent Sr(4), one Nb(1), and one Nb(2) atom. In the fifth O site, O(5) is bonded in a 4-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), one Nb(2), and one Nb(3) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), one Nb(3), and one Nb(5) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Sr(4), one Nb(2), and one Nb(3) atom. In the eighth O site, O(8) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Sr(3), one Nb(4), and one Nb(5) atom. In the ninth O site, O(9) is bonded in a 2-coordinate geometry to two equivalent Sr(2), two equivalent Sr(3), one Nb(3), and one Nb(5) atom. In the tenth O site, O(10) is bonded to three equivalent Sr(1) and one Nb(4) atom to form OSr3Nb tetrahedra that share corners with six equivalent O(10)Sr3Nb tetrahedra,  a cornercorner with one O(11)Sr2Nb2 trigonal pyramid, corners with two equivalent O(12)Sr3Nb trigonal pyramids, and edges with four equivalent O(12)Sr3Nb trigonal pyramids. In the eleventh O site, O(11) is bonded to two equivalent Sr(3), one Nb(4), and one Nb(5) atom to form distorted OSr2Nb2 trigonal pyramids that share  a cornercorner with one O(10)Sr3Nb tetrahedra,  a cornercorner with one O(12)Sr3Nb trigonal pyramid, and corners with two equivalent O(11)Sr2Nb2 trigonal pyramids. In the twelfth O site, O(12) is bonded to three equivalent Sr(1) and one Nb(4) atom to form distorted OSr3Nb trigonal pyramids that share corners with two equivalent O(10)Sr3Nb tetrahedra,  a cornercorner with one O(11)Sr2Nb2 trigonal pyramid, corners with six equivalent O(12)Sr3Nb trigonal pyramids, and edges with four equivalent O(10)Sr3Nb tetrahedra. In the thirteenth O site, O(13) is bonded in a distorted linear geometry to one Sr(2), two equivalent Sr(3), and two equivalent Nb(5) atoms. In the fourteenth O site, O(14) is bonded to one Sr(2), two equivalent Sr(4), and two equivalent Nb(2) atoms to form distorted OSr3Nb2 square pyramids that share corners with four equivalent O(14)Sr3Nb2 square pyramids, corners with two equivalent O(2)Sr2Nb2 tetrahedra, and edges with two equivalent O(2)Sr2Nb2 tetrahedra. In the fifteenth O site, O(15) is bonded in a distorted linear geometry to one Sr(3), one Sr(4), two equivalent Sr(2), and two equivalent Nb(3) atoms. In the sixteenth O site, O(16) is bonded in a 4-coordinate geometry to one Sr(4), one Sr(5), and two equivalent Nb(1) atoms. is represented by the CIF card [CIF]
data_Sr5Nb5O16
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   4.029
_cell_length_b   5.714
_cell_length_c   32.948
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   758.545
_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
  Sr  Sr0  1  0.000  0.047  0.530  1.0
  Sr  Sr1  1  0.000  0.068  0.751  1.0
  Sr  Sr2  1  0.000  0.575  0.663  1.0
  Sr  Sr3  1  0.000  0.560  0.841  1.0
  Sr  Sr4  1  0.000  0.130  0.967  1.0
  Sr  Sr5  1  0.500  0.630  0.033  1.0
  Sr  Sr6  1  0.500  0.060  0.159  1.0
  Sr  Sr7  1  0.500  0.568  0.249  1.0
  Sr  Sr8  1  0.500  0.075  0.337  1.0
  Sr  Sr9  1  0.500  0.547  0.470  1.0
  Nb  Nb10  1  0.000  0.099  0.073  1.0
  Nb  Nb11  1  0.000  0.571  0.160  1.0
  Nb  Nb12  1  0.000  0.069  0.249  1.0
  Nb  Nb13  1  0.000  0.059  0.425  1.0
  Nb  Nb14  1  0.000  0.567  0.339  1.0
  Nb  Nb15  1  0.500  0.559  0.575  1.0
  Nb  Nb16  1  0.500  0.067  0.661  1.0
  Nb  Nb17  1  0.500  0.569  0.751  1.0
  Nb  Nb18  1  0.500  0.071  0.840  1.0
  Nb  Nb19  1  0.500  0.599  0.927  1.0
  O  O20  1  0.000  0.363  0.040  1.0
  O  O21  1  0.000  0.273  0.129  1.0
  O  O22  1  0.000  0.881  0.030  1.0
  O  O23  1  0.000  0.796  0.118  1.0
  O  O24  1  0.000  0.353  0.213  1.0
  O  O25  1  0.000  0.295  0.297  1.0
  O  O26  1  0.000  0.844  0.202  1.0
  O  O27  1  0.000  0.322  0.380  1.0
  O  O28  1  0.000  0.789  0.287  1.0
  O  O29  1  0.000  0.287  0.466  1.0
  O  O30  1  0.000  0.858  0.372  1.0
  O  O31  1  0.000  0.806  0.461  1.0
  O  O32  1  0.000  0.070  0.665  1.0
  O  O33  1  0.000  0.060  0.834  1.0
  O  O34  1  0.000  0.568  0.751  1.0
  O  O35  1  0.000  0.570  0.919  1.0
  O  O36  1  0.500  0.070  0.081  1.0
  O  O37  1  0.500  0.560  0.166  1.0
  O  O38  1  0.500  0.068  0.249  1.0
  O  O39  1  0.500  0.570  0.335  1.0
  O  O40  1  0.500  0.306  0.539  1.0
  O  O41  1  0.500  0.787  0.534  1.0
  O  O42  1  0.500  0.289  0.713  1.0
  O  O43  1  0.500  0.822  0.620  1.0
  O  O44  1  0.500  0.358  0.628  1.0
  O  O45  1  0.500  0.795  0.703  1.0
  O  O46  1  0.500  0.853  0.787  1.0
  O  O47  1  0.500  0.344  0.798  1.0
  O  O48  1  0.500  0.296  0.882  1.0
  O  O49  1  0.500  0.773  0.871  1.0
  O  O50  1  0.500  0.381  0.970  1.0
  O  O51  1  0.500  0.863  0.960  1.0
[/CIF]
.