The compound described by Li2CaTa2O7 crystallizes in the tetragonal I4/mmm space group. Li(1) is bonded to four equivalent O(2) atoms to form distorted LiO4 trigonal pyramids that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Li(1)O4 trigonal pyramids, and edges with four equivalent Li(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles are 71°. Ca(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ca(1)O12 cuboctahedra, and faces with eight equivalent Ta(1)O6 octahedra. Ta(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form TaO6 octahedra that share corners with five equivalent Ta(1)O6 octahedra, corners with four equivalent Li(1)O4 trigonal pyramids, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to four equivalent Li(1) and one Ta(1) atom to form distorted OLi4Ta trigonal bipyramids that share  a cornercorner with one O(3)Ca4Ta2 octahedra, corners with four equivalent O(2)Li4Ta trigonal bipyramids, and edges with four equivalent O(2)Li4Ta trigonal bipyramids. The corner-sharing octahedra are not tilted. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Ta(1) atoms to form distorted OCa4Ta2 octahedra that share corners with four equivalent O(3)Ca4Ta2 octahedra, corners with two equivalent O(2)Li4Ta trigonal bipyramids, and edges with four equivalent O(3)Ca4Ta2 octahedra. The corner-sharing octahedra are not tilted. is represented by the CIF card [CIF]
data_Li2CaTa2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.720
_cell_length_b   9.720
_cell_length_c   9.720
_cell_angle_alpha   156.523
_cell_angle_beta   156.523
_cell_angle_gamma   33.442
_symmetry_Int_Tables_number   1
_cell_volume   145.625
_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
  Li  Li0  1  0.750  0.250  0.500  1.0
  Li  Li1  1  0.250  0.750  0.500  1.0
  Ca  Ca2  1  0.000  0.000  0.000  1.0
  Ta  Ta3  1  0.611  0.611  0.000  1.0
  Ta  Ta4  1  0.389  0.389  0.000  1.0
  O  O5  1  0.600  0.100  0.500  1.0
  O  O6  1  0.286  0.286  0.000  1.0
  O  O7  1  0.900  0.400  0.500  1.0
  O  O8  1  0.400  0.900  0.500  1.0
  O  O9  1  0.714  0.714  0.000  1.0
  O  O10  1  0.100  0.600  0.500  1.0
  O  O11  1  0.500  0.500  0.000  1.0
[/CIF]
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The compound described by Li2CaTa2O7 crystallizes in the tetragonal I4/mmm space group. Li(1) is bonded to four equivalent O(2) atoms to form distorted LiO4 trigonal pyramids that share corners with four equivalent Ta(1)O6 octahedra, corners with four equivalent Li(1)O4 trigonal pyramids, and edges with four equivalent Li(1)O4 trigonal pyramids. The corner-sharing octahedral tilt angles are 71°. Ca(1) is bonded to four equivalent O(3) and eight equivalent O(1) atoms to form CaO12 cuboctahedra that share corners with four equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ca(1)O12 cuboctahedra, and faces with eight equivalent Ta(1)O6 octahedra. Ta(1) is bonded to one O(2), one O(3), and four equivalent O(1) atoms to form TaO6 octahedra that share corners with five equivalent Ta(1)O6 octahedra, corners with four equivalent Li(1)O4 trigonal pyramids, and faces with four equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 0-13°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a 2-coordinate geometry to two equivalent Ca(1) and two equivalent Ta(1) atoms. In the second O site, O(2) is bonded to four equivalent Li(1) and one Ta(1) atom to form distorted OLi4Ta trigonal bipyramids that share  a cornercorner with one O(3)Ca4Ta2 octahedra, corners with four equivalent O(2)Li4Ta trigonal bipyramids, and edges with four equivalent O(2)Li4Ta trigonal bipyramids. The corner-sharing octahedra are not tilted. In the third O site, O(3) is bonded to four equivalent Ca(1) and two equivalent Ta(1) atoms to form distorted OCa4Ta2 octahedra that share corners with four equivalent O(3)Ca4Ta2 octahedra, corners with two equivalent O(2)Li4Ta trigonal bipyramids, and edges with four equivalent O(3)Ca4Ta2 octahedra. The corner-sharing octahedra are not tilted. is represented by the CIF card [CIF]
data_Li2CaTa2O7
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   9.720
_cell_length_b   9.720
_cell_length_c   9.720
_cell_angle_alpha   156.523
_cell_angle_beta   156.523
_cell_angle_gamma   33.442
_symmetry_Int_Tables_number   1
_cell_volume   145.625
_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
  Li  Li0  1  0.750  0.250  0.500  1.0
  Li  Li1  1  0.250  0.750  0.500  1.0
  Ca  Ca2  1  0.000  0.000  0.000  1.0
  Ta  Ta3  1  0.611  0.611  0.000  1.0
  Ta  Ta4  1  0.389  0.389  0.000  1.0
  O  O5  1  0.600  0.100  0.500  1.0
  O  O6  1  0.286  0.286  0.000  1.0
  O  O7  1  0.900  0.400  0.500  1.0
  O  O8  1  0.400  0.900  0.500  1.0
  O  O9  1  0.714  0.714  0.000  1.0
  O  O10  1  0.100  0.600  0.500  1.0
  O  O11  1  0.500  0.500  0.000  1.0
[/CIF]
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