The material structure described by Ca3Ta2O8 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CaO6 octahedra that share corners with six equivalent Ta(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent Ca(2)O6 octahedra. In the second Ca site, Ca(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CaO6 octahedra that share corners with six equivalent Ta(1)O4 tetrahedra and edges with four equivalent Ca(1)O6 octahedra. Ta(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form TaO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with six equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-56°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Ta(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Ca(2), two equivalent Ca(1), and one Ta(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one Ta(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3Ta2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.229
_cell_length_b   7.229
_cell_length_c   9.307
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   123.336
_symmetry_Int_Tables_number   1
_cell_volume   406.357
_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  0.391  0.109  0.750  1.0
  Ca  Ca1  1  0.000  0.000  0.000  1.0
  Ca  Ca2  1  0.109  0.391  0.250  1.0
  Ca  Ca3  1  0.891  0.609  0.750  1.0
  Ca  Ca4  1  0.500  0.500  0.500  1.0
  Ca  Ca5  1  0.609  0.891  0.250  1.0
  Ta  Ta6  1  0.616  0.384  0.118  1.0
  Ta  Ta7  1  0.884  0.116  0.618  1.0
  Ta  Ta8  1  0.384  0.616  0.882  1.0
  Ta  Ta9  1  0.116  0.884  0.382  1.0
  O  O10  1  0.336  0.106  0.498  1.0
  O  O11  1  0.394  0.164  0.002  1.0
  O  O12  1  0.501  0.499  0.752  1.0
  O  O13  1  0.999  0.001  0.252  1.0
  O  O14  1  0.743  0.257  0.221  1.0
  O  O15  1  0.757  0.243  0.721  1.0
  O  O16  1  0.106  0.336  0.502  1.0
  O  O17  1  0.836  0.606  0.002  1.0
  O  O18  1  0.164  0.394  0.998  1.0
  O  O19  1  0.894  0.664  0.498  1.0
  O  O20  1  0.499  0.501  0.248  1.0
  O  O21  1  0.257  0.743  0.779  1.0
  O  O22  1  0.243  0.757  0.279  1.0
  O  O23  1  0.001  0.999  0.748  1.0
  O  O24  1  0.606  0.836  0.998  1.0
  O  O25  1  0.664  0.894  0.502  1.0
[/CIF]
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The material structure described by Ca3Ta2O8 crystallizes in the orthorhombic Cmce space group. There are two inequivalent Ca sites. In the first Ca site, Ca(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms to form CaO6 octahedra that share corners with six equivalent Ta(1)O4 tetrahedra, edges with two equivalent Ca(1)O6 octahedra, and edges with two equivalent Ca(2)O6 octahedra. In the second Ca site, Ca(2) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form CaO6 octahedra that share corners with six equivalent Ta(1)O4 tetrahedra and edges with four equivalent Ca(1)O6 octahedra. Ta(1) is bonded to one O(2), one O(3), and two equivalent O(1) atoms to form TaO4 tetrahedra that share corners with three equivalent Ca(2)O6 octahedra and corners with six equivalent Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-56°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Ca(1), one Ca(2), and one Ta(1) atom. In the second O site, O(2) is bonded in a rectangular see-saw-like geometry to one Ca(2), two equivalent Ca(1), and one Ta(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one Ta(1) atom. is represented by the Crystallographic Information File (CIF) [CIF]
data_Ca3Ta2O8
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   7.229
_cell_length_b   7.229
_cell_length_c   9.307
_cell_angle_alpha   90.000
_cell_angle_beta   90.000
_cell_angle_gamma   123.336
_symmetry_Int_Tables_number   1
_cell_volume   406.357
_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  0.391  0.109  0.750  1.0
  Ca  Ca1  1  0.000  0.000  0.000  1.0
  Ca  Ca2  1  0.109  0.391  0.250  1.0
  Ca  Ca3  1  0.891  0.609  0.750  1.0
  Ca  Ca4  1  0.500  0.500  0.500  1.0
  Ca  Ca5  1  0.609  0.891  0.250  1.0
  Ta  Ta6  1  0.616  0.384  0.118  1.0
  Ta  Ta7  1  0.884  0.116  0.618  1.0
  Ta  Ta8  1  0.384  0.616  0.882  1.0
  Ta  Ta9  1  0.116  0.884  0.382  1.0
  O  O10  1  0.336  0.106  0.498  1.0
  O  O11  1  0.394  0.164  0.002  1.0
  O  O12  1  0.501  0.499  0.752  1.0
  O  O13  1  0.999  0.001  0.252  1.0
  O  O14  1  0.743  0.257  0.221  1.0
  O  O15  1  0.757  0.243  0.721  1.0
  O  O16  1  0.106  0.336  0.502  1.0
  O  O17  1  0.836  0.606  0.002  1.0
  O  O18  1  0.164  0.394  0.998  1.0
  O  O19  1  0.894  0.664  0.498  1.0
  O  O20  1  0.499  0.501  0.248  1.0
  O  O21  1  0.257  0.743  0.779  1.0
  O  O22  1  0.243  0.757  0.279  1.0
  O  O23  1  0.001  0.999  0.748  1.0
  O  O24  1  0.606  0.836  0.998  1.0
  O  O25  1  0.664  0.894  0.502  1.0
[/CIF]
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