The material described by Li2Ca2Ta3O10 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 72°. Ca(1) is bonded to four equivalent O(1), four equivalent O(3), and four equivalent O(4) atoms to form distorted CaO12 cuboctahedra that share corners with eight equivalent Ca(1)O12 cuboctahedra, faces with five equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ta(1)O6 octahedra, and faces with four equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(2), one O(4), and four equivalent O(1) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(2)O6 octahedra, corners with four 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 0-15°. In the second Ta site, Ta(2) is bonded to two equivalent O(4) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ta(2)O6 octahedra, and faces with eight equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like 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 a mixture of distorted edge and corner-sharing OLi4Ta trigonal bipyramids. In the third O site, O(3) is bonded in a linear geometry to four equivalent Ca(1) and two equivalent Ta(2) atoms. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent Ca(1), one Ta(1), and one Ta(2) atom. is represented by the CIF file [CIF]
data_Li2Ca2Ta3O10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.562
_cell_length_b   13.562
_cell_length_c   13.562
_cell_angle_alpha   163.094
_cell_angle_beta   163.094
_cell_angle_gamma   23.997
_symmetry_Int_Tables_number   1
_cell_volume   210.902
_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  0.250  0.750  0.500  1.0
  Li  Li1  1  0.750  0.250  0.500  1.0
  Ca  Ca2  1  0.415  0.415  0.000  1.0
  Ca  Ca3  1  0.585  0.585  0.000  1.0
  Ta  Ta4  1  0.846  0.846  0.000  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Ta  Ta6  1  0.154  0.154  0.000  1.0
  O  O7  1  0.356  0.856  0.500  1.0
  O  O8  1  0.774  0.774  0.000  1.0
  O  O9  1  0.226  0.226  0.000  1.0
  O  O10  1  0.500  0.000  0.500  1.0
  O  O11  1  0.856  0.356  0.500  1.0
  O  O12  1  0.000  0.500  0.500  1.0
  O  O13  1  0.925  0.925  0.000  1.0
  O  O14  1  0.075  0.075  0.000  1.0
  O  O15  1  0.144  0.644  0.500  1.0
  O  O16  1  0.644  0.144  0.500  1.0
[/CIF]
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The material described by Li2Ca2Ta3O10 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 72°. Ca(1) is bonded to four equivalent O(1), four equivalent O(3), and four equivalent O(4) atoms to form distorted CaO12 cuboctahedra that share corners with eight equivalent Ca(1)O12 cuboctahedra, faces with five equivalent Ca(1)O12 cuboctahedra, faces with four equivalent Ta(1)O6 octahedra, and faces with four equivalent Ta(2)O6 octahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(2), one O(4), and four equivalent O(1) atoms to form TaO6 octahedra that share  a cornercorner with one Ta(2)O6 octahedra, corners with four 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 0-15°. In the second Ta site, Ta(2) is bonded to two equivalent O(4) and four equivalent O(3) atoms to form TaO6 octahedra that share corners with two equivalent Ta(1)O6 octahedra, corners with four equivalent Ta(2)O6 octahedra, and faces with eight equivalent Ca(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted see-saw-like 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 a mixture of distorted edge and corner-sharing OLi4Ta trigonal bipyramids. In the third O site, O(3) is bonded in a linear geometry to four equivalent Ca(1) and two equivalent Ta(2) atoms. In the fourth O site, O(4) is bonded in a distorted linear geometry to four equivalent Ca(1), one Ta(1), and one Ta(2) atom. is represented by the CIF file [CIF]
data_Li2Ca2Ta3O10
_symmetry_space_group_name_H-M   'P 1'
_cell_length_a   13.562
_cell_length_b   13.562
_cell_length_c   13.562
_cell_angle_alpha   163.094
_cell_angle_beta   163.094
_cell_angle_gamma   23.997
_symmetry_Int_Tables_number   1
_cell_volume   210.902
_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  0.250  0.750  0.500  1.0
  Li  Li1  1  0.750  0.250  0.500  1.0
  Ca  Ca2  1  0.415  0.415  0.000  1.0
  Ca  Ca3  1  0.585  0.585  0.000  1.0
  Ta  Ta4  1  0.846  0.846  0.000  1.0
  Ta  Ta5  1  0.000  0.000  0.000  1.0
  Ta  Ta6  1  0.154  0.154  0.000  1.0
  O  O7  1  0.356  0.856  0.500  1.0
  O  O8  1  0.774  0.774  0.000  1.0
  O  O9  1  0.226  0.226  0.000  1.0
  O  O10  1  0.500  0.000  0.500  1.0
  O  O11  1  0.856  0.356  0.500  1.0
  O  O12  1  0.000  0.500  0.500  1.0
  O  O13  1  0.925  0.925  0.000  1.0
  O  O14  1  0.075  0.075  0.000  1.0
  O  O15  1  0.144  0.644  0.500  1.0
  O  O16  1  0.644  0.144  0.500  1.0
[/CIF]
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