The material described by Rb2CaNb2(TeO6)2 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. Ca(1) is bonded in a distorted hexagonal planar geometry to two equivalent O(1) and four equivalent O(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra and corners with four equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-49°. In the second Nb site, Nb(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-40°. Te(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TeO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and corners with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-49°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(1), one Ca(1), and two equivalent Te(1) atoms. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Rb(1), one Nb(2), and one Te(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(1), one Ca(1), one Nb(1), and one Te(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Rb2CaNb2(TeO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.642
_cell_length_b   7.656
_cell_length_c   7.478
_cell_angle_alpha   90.000
_cell_angle_beta   60.705
_cell_angle_gamma   121.581
_symmetry_Int_Tables_number   1
_cell_volume   305.134
_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
  Rb  Rb0  1  0.858  0.325  0.321  1.0
  Rb  Rb1  1  0.142  0.675  0.679  1.0
  Ca  Ca2  1  0.500  0.500  0.500  1.0
  Nb  Nb3  1  0.500  0.500  0.000  1.0
  Nb  Nb4  1  0.500  0.000  0.000  1.0
  Te  Te5  1  0.000  0.000  0.500  1.0
  Te  Te6  1  0.000  0.000  0.000  1.0
  O  O7  1  0.842  0.918  0.329  1.0
  O  O8  1  0.612  0.312  0.944  1.0
  O  O9  1  0.248  0.934  0.936  1.0
  O  O10  1  0.257  0.330  0.328  1.0
  O  O11  1  0.257  0.330  0.915  1.0
  O  O12  1  0.248  0.934  0.317  1.0
  O  O13  1  0.158  0.082  0.671  1.0
  O  O14  1  0.388  0.688  0.056  1.0
  O  O15  1  0.752  0.066  0.064  1.0
  O  O16  1  0.743  0.670  0.672  1.0
  O  O17  1  0.743  0.670  0.085  1.0
  O  O18  1  0.752  0.066  0.683  1.0
[/CIF]
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The material described by Rb2CaNb2(TeO6)2 crystallizes in the monoclinic C2/m space group. Rb(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms. Ca(1) is bonded in a distorted hexagonal planar geometry to two equivalent O(1) and four equivalent O(4) atoms. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NbO6 octahedra that share corners with two equivalent Nb(2)O6 octahedra and corners with four equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-49°. In the second Nb site, Nb(2) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form NbO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with four equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 35-40°. Te(1) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form TeO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra, corners with two equivalent Nb(2)O6 octahedra, and corners with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 40-49°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Rb(1), one Ca(1), and two equivalent Te(1) atoms. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Rb(1), one Nb(2), and one Te(1) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Rb(1), one Ca(1), one Nb(1), and one Te(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Rb2CaNb2(TeO6)2
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.642
_cell_length_b   7.656
_cell_length_c   7.478
_cell_angle_alpha   90.000
_cell_angle_beta   60.705
_cell_angle_gamma   121.581
_symmetry_Int_Tables_number   1
_cell_volume   305.134
_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
  Rb  Rb0  1  0.858  0.325  0.321  1.0
  Rb  Rb1  1  0.142  0.675  0.679  1.0
  Ca  Ca2  1  0.500  0.500  0.500  1.0
  Nb  Nb3  1  0.500  0.500  0.000  1.0
  Nb  Nb4  1  0.500  0.000  0.000  1.0
  Te  Te5  1  0.000  0.000  0.500  1.0
  Te  Te6  1  0.000  0.000  0.000  1.0
  O  O7  1  0.842  0.918  0.329  1.0
  O  O8  1  0.612  0.312  0.944  1.0
  O  O9  1  0.248  0.934  0.936  1.0
  O  O10  1  0.257  0.330  0.328  1.0
  O  O11  1  0.257  0.330  0.915  1.0
  O  O12  1  0.248  0.934  0.317  1.0
  O  O13  1  0.158  0.082  0.671  1.0
  O  O14  1  0.388  0.688  0.056  1.0
  O  O15  1  0.752  0.066  0.064  1.0
  O  O16  1  0.743  0.670  0.672  1.0
  O  O17  1  0.743  0.670  0.085  1.0
  O  O18  1  0.752  0.066  0.683  1.0
[/CIF]
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