The crystal structure described by Sr2CaNbO6 crystallizes in the tetragonal P-4 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Sr site, Sr(2) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and corners with two equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-34°. In the second Ca site, Ca(2) is bonded to two equivalent O(6) and four equivalent O(8) atoms to form CaO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra and corners with four equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. In the third Ca site, Ca(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form CaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Ca(3)O6 octahedra and corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-34°. In the second Nb site, Nb(2) is bonded to two equivalent O(6) and four equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Ca(2)O6 octahedra and corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. In the third Nb site, Nb(3) is bonded to one O(2), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra, and corners with two equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. There are eight inequivalent O sites. In the first O site, O(6) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(2), and one Nb(2) atom to form distorted OSr4CaNb octahedra that share corners with two equivalent O(6)Sr4CaNb octahedra, corners with four equivalent O(3)Sr4CaNb octahedra, corners with four equivalent O(1)Sr2CaNb tetrahedra, corners with four equivalent O(5)Sr2CaNb tetrahedra, edges with two equivalent O(2)Sr4CaNb octahedra, edges with two equivalent O(7)Sr4CaNb octahedra, edges with four equivalent O(4)Sr2CaNb tetrahedra, and edges with four equivalent O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the second O site, O(7) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(1), and one Nb(3) atom to form distorted OSr4CaNb octahedra that share corners with six equivalent O(2)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, edges with two equivalent O(3)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, edges with two equivalent O(1)Sr2CaNb tetrahedra, edges with two equivalent O(4)Sr2CaNb tetrahedra, edges with two equivalent O(5)Sr2CaNb tetrahedra, and edges with two equivalent O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(8) is bonded to one Sr(1), one Sr(2), one Ca(2), and one Nb(3) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(3)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with four equivalent O(8)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, and  an edgeedge with one O(1)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 67-68°. In the fourth O site, O(1) is bonded to one Sr(1), one Sr(2), one Ca(3), and one Nb(3) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(6)Sr4CaNb octahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, corners with four equivalent O(1)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(3)Sr4CaNb octahedra, and  an edgeedge with one O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 67-68°. In the fifth O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(1), and one Nb(3) atom to form distorted OSr4CaNb octahedra that share corners with six equivalent O(7)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, edges with two equivalent O(3)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, edges with two equivalent O(1)Sr2CaNb tetrahedra, edges with two equivalent O(4)Sr2CaNb tetrahedra, edges with two equivalent O(5)Sr2CaNb tetrahedra, and edges with two equivalent O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the sixth O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(3), and one Nb(1) atom to form distorted OSr4CaNb octahedra that share corners with two equivalent O(3)Sr4CaNb octahedra, corners with four equivalent O(6)Sr4CaNb octahedra, corners with four equivalent O(4)Sr2CaNb tetrahedra, corners with four equivalent O(8)Sr2CaNb tetrahedra, edges with two equivalent O(2)Sr4CaNb octahedra, edges with two equivalent O(7)Sr4CaNb octahedra, edges with four equivalent O(1)Sr2CaNb tetrahedra, and edges with four equivalent O(5)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the seventh O site, O(4) is bonded to one Sr(1), one Sr(2), one Ca(1), and one Nb(2) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(3)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, corners with four equivalent O(4)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, and  an edgeedge with one O(5)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°. In the eighth O site, O(5) is bonded to one Sr(1), one Sr(2), one Ca(1), and one Nb(1) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(6)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, corners with four equivalent O(5)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(3)Sr4CaNb octahedra, and  an edgeedge with one O(4)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sr2CaNbO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.853
_cell_length_b   5.853
_cell_length_c   8.644
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   296.156
_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
  Ca  Ca0  1  0.500  0.500  1.000  1.0
  Ca  Ca1  1  0.000  0.000  0.500  1.0
  Nb  Nb2  1  0.000  0.000  0.000  1.0
  Nb  Nb3  1  0.500  0.500  0.500  1.0
  O  O4  1  0.652  0.810  0.501  1.0
  O  O5  1  0.348  0.190  0.501  1.0
  O  O6  1  0.190  0.652  0.499  1.0
  O  O7  1  0.810  0.348  0.499  1.0
  O  O8  1  0.500  0.500  0.266  1.0
  O  O9  1  0.500  0.500  0.734  1.0
  O  O10  1  0.000  0.000  0.766  1.0
  O  O11  1  0.000  0.000  0.234  1.0
  O  O12  1  0.306  0.157  0.001  1.0
  O  O13  1  0.694  0.843  0.001  1.0
  O  O14  1  0.843  0.306  0.999  1.0
  O  O15  1  0.157  0.694  0.999  1.0
  Sr  Sr16  1  0.500  0.000  0.752  1.0
  Sr  Sr17  1  1.000  0.500  0.248  1.0
  Sr  Sr18  1  1.000  0.500  0.752  1.0
  Sr  Sr19  1  0.500  0.000  0.248  1.0
[/CIF]
.
The crystal structure described by Sr2CaNbO6 crystallizes in the tetragonal P-4 space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. In the second Sr site, Sr(2) is bonded in a distorted body-centered cubic geometry to one O(1), one O(2), one O(3), one O(4), one O(5), one O(6), one O(7), and one O(8) atom. There are three inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to one O(2), one O(7), two equivalent O(4), and two equivalent O(5) atoms to form CaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and corners with two equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-34°. In the second Ca site, Ca(2) is bonded to two equivalent O(6) and four equivalent O(8) atoms to form CaO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra and corners with four equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. In the third Ca site, Ca(3) is bonded to two equivalent O(3) and four equivalent O(1) atoms to form CaO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Nb(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. There are three inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(3) and four equivalent O(5) atoms to form NbO6 octahedra that share corners with two equivalent Ca(3)O6 octahedra and corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-34°. In the second Nb site, Nb(2) is bonded to two equivalent O(6) and four equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Ca(2)O6 octahedra and corners with four equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-33°. In the third Nb site, Nb(3) is bonded to one O(2), one O(7), two equivalent O(1), and two equivalent O(8) atoms to form NbO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent Ca(2)O6 octahedra, and corners with two equivalent Ca(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 0-35°. There are eight inequivalent O sites. In the first O site, O(6) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(2), and one Nb(2) atom to form distorted OSr4CaNb octahedra that share corners with two equivalent O(6)Sr4CaNb octahedra, corners with four equivalent O(3)Sr4CaNb octahedra, corners with four equivalent O(1)Sr2CaNb tetrahedra, corners with four equivalent O(5)Sr2CaNb tetrahedra, edges with two equivalent O(2)Sr4CaNb octahedra, edges with two equivalent O(7)Sr4CaNb octahedra, edges with four equivalent O(4)Sr2CaNb tetrahedra, and edges with four equivalent O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the second O site, O(7) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(1), and one Nb(3) atom to form distorted OSr4CaNb octahedra that share corners with six equivalent O(2)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, edges with two equivalent O(3)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, edges with two equivalent O(1)Sr2CaNb tetrahedra, edges with two equivalent O(4)Sr2CaNb tetrahedra, edges with two equivalent O(5)Sr2CaNb tetrahedra, and edges with two equivalent O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(8) is bonded to one Sr(1), one Sr(2), one Ca(2), and one Nb(3) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(3)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with four equivalent O(8)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, and  an edgeedge with one O(1)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 67-68°. In the fourth O site, O(1) is bonded to one Sr(1), one Sr(2), one Ca(3), and one Nb(3) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(6)Sr4CaNb octahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, corners with four equivalent O(1)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(3)Sr4CaNb octahedra, and  an edgeedge with one O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 67-68°. In the fifth O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(1), and one Nb(3) atom to form distorted OSr4CaNb octahedra that share corners with six equivalent O(7)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, edges with two equivalent O(3)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, edges with two equivalent O(1)Sr2CaNb tetrahedra, edges with two equivalent O(4)Sr2CaNb tetrahedra, edges with two equivalent O(5)Sr2CaNb tetrahedra, and edges with two equivalent O(8)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the sixth O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sr(2), one Ca(3), and one Nb(1) atom to form distorted OSr4CaNb octahedra that share corners with two equivalent O(3)Sr4CaNb octahedra, corners with four equivalent O(6)Sr4CaNb octahedra, corners with four equivalent O(4)Sr2CaNb tetrahedra, corners with four equivalent O(8)Sr2CaNb tetrahedra, edges with two equivalent O(2)Sr4CaNb octahedra, edges with two equivalent O(7)Sr4CaNb octahedra, edges with four equivalent O(1)Sr2CaNb tetrahedra, and edges with four equivalent O(5)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 0-5°. In the seventh O site, O(4) is bonded to one Sr(1), one Sr(2), one Ca(1), and one Nb(2) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(3)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(5)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, corners with four equivalent O(4)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(6)Sr4CaNb octahedra, and  an edgeedge with one O(5)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°. In the eighth O site, O(5) is bonded to one Sr(1), one Sr(2), one Ca(1), and one Nb(1) atom to form distorted OSr2CaNb tetrahedra that share  a cornercorner with one O(2)Sr4CaNb octahedra,  a cornercorner with one O(7)Sr4CaNb octahedra, corners with two equivalent O(6)Sr4CaNb octahedra, corners with two equivalent O(1)Sr2CaNb tetrahedra, corners with two equivalent O(4)Sr2CaNb tetrahedra, corners with two equivalent O(8)Sr2CaNb tetrahedra, corners with four equivalent O(5)Sr2CaNb tetrahedra,  an edgeedge with one O(2)Sr4CaNb octahedra,  an edgeedge with one O(7)Sr4CaNb octahedra, edges with two equivalent O(3)Sr4CaNb octahedra, and  an edgeedge with one O(4)Sr2CaNb tetrahedra. The corner-sharing octahedral tilt angles range from 66-67°. is represented by the Crystallographic Information File (CIF) [CIF]
data_Sr2CaNbO6
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   5.853
_cell_length_b   5.853
_cell_length_c   8.644
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   90.000
_symmetry_Int_Tables_number   1
_cell_volume   296.156
_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
  Ca  Ca0  1  0.500  0.500  1.000  1.0
  Ca  Ca1  1  0.000  0.000  0.500  1.0
  Nb  Nb2  1  0.000  0.000  0.000  1.0
  Nb  Nb3  1  0.500  0.500  0.500  1.0
  O  O4  1  0.652  0.810  0.501  1.0
  O  O5  1  0.348  0.190  0.501  1.0
  O  O6  1  0.190  0.652  0.499  1.0
  O  O7  1  0.810  0.348  0.499  1.0
  O  O8  1  0.500  0.500  0.266  1.0
  O  O9  1  0.500  0.500  0.734  1.0
  O  O10  1  0.000  0.000  0.766  1.0
  O  O11  1  0.000  0.000  0.234  1.0
  O  O12  1  0.306  0.157  0.001  1.0
  O  O13  1  0.694  0.843  0.001  1.0
  O  O14  1  0.843  0.306  0.999  1.0
  O  O15  1  0.157  0.694  0.999  1.0
  Sr  Sr16  1  0.500  0.000  0.752  1.0
  Sr  Sr17  1  1.000  0.500  0.248  1.0
  Sr  Sr18  1  1.000  0.500  0.752  1.0
  Sr  Sr19  1  0.500  0.000  0.248  1.0
[/CIF]
.