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.
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°. All Li(1)-O(2) bond lengths are 2.09 Å. 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. All Ca(1)-O(1) bond lengths are 2.54 Å. All Ca(1)-O(3) bond lengths are 3.01 Å. All Ca(1)-O(4) bond lengths are 2.83 Å. 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°. The Ta(1)-O(2) bond length is 1.90 Å. The Ta(1)-O(4) bond length is 2.11 Å. All Ta(1)-O(1) bond lengths are 2.01 Å. 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. Both Ta(2)-O(4) bond lengths are 1.99 Å. All Ta(2)-O(3) bond lengths are 1.99 Å. 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.