NaTaO3Ta2O5 crystallizes in the orthorhombic Ibam space group. Na(1) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form distorted NaO8 hexagonal bipyramids that share edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Ta(2)O8 hexagonal bipyramids, and edges with eight equivalent Ta(1)O7 pentagonal bipyramids. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(3), two equivalent O(2), and four equivalent O(1) atoms to form distorted TaO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O8 hexagonal bipyramids, corners with two equivalent Ta(1)O7 pentagonal bipyramids, edges with two equivalent Ta(2)O8 hexagonal bipyramids, edges with four equivalent Na(1)O8 hexagonal bipyramids, and edges with two equivalent Ta(1)O7 pentagonal bipyramids. In the second Ta site, Ta(2) is bonded to four equivalent O(1) and four equivalent O(3) atoms to form distorted TaO8 hexagonal bipyramids that share corners with four equivalent Ta(1)O7 pentagonal bipyramids, edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Ta(2)O8 hexagonal bipyramids, and edges with four equivalent Ta(1)O7 pentagonal bipyramids. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Ta(2), and two equivalent Ta(1) atoms to form distorted ONaTa3 trigonal pyramids that share corners with four equivalent O(2)Na2Ta2 tetrahedra, corners with eight equivalent O(1)NaTa3 trigonal pyramids, edges with two equivalent O(2)Na2Ta2 tetrahedra, and edges with two equivalent O(1)NaTa3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Na(1) and two equivalent Ta(1) atoms to form distorted ONa2Ta2 tetrahedra that share corners with six equivalent O(2)Na2Ta2 tetrahedra, corners with eight equivalent O(1)NaTa3 trigonal pyramids,  an edgeedge with one O(2)Na2Ta2 tetrahedra, and edges with four equivalent O(1)NaTa3 trigonal pyramids. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ta(1) and two equivalent Ta(2) atoms.
NaTaO3Ta2O5 crystallizes in the orthorhombic Ibam space group. Na(1) is bonded to four equivalent O(1) and four equivalent O(2) atoms to form distorted NaO8 hexagonal bipyramids that share edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Ta(2)O8 hexagonal bipyramids, and edges with eight equivalent Ta(1)O7 pentagonal bipyramids. All Na(1)-O(1) bond lengths are 2.71 Å. All Na(1)-O(2) bond lengths are 2.55 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded to one O(3), two equivalent O(2), and four equivalent O(1) atoms to form distorted TaO7 pentagonal bipyramids that share corners with two equivalent Ta(2)O8 hexagonal bipyramids, corners with two equivalent Ta(1)O7 pentagonal bipyramids, edges with two equivalent Ta(2)O8 hexagonal bipyramids, edges with four equivalent Na(1)O8 hexagonal bipyramids, and edges with two equivalent Ta(1)O7 pentagonal bipyramids. The Ta(1)-O(3) bond length is 1.98 Å. There is one shorter (1.95 Å) and one longer (2.05 Å) Ta(1)-O(2) bond length. There are two shorter (1.98 Å) and two longer (2.35 Å) Ta(1)-O(1) bond lengths. In the second Ta site, Ta(2) is bonded to four equivalent O(1) and four equivalent O(3) atoms to form distorted TaO8 hexagonal bipyramids that share corners with four equivalent Ta(1)O7 pentagonal bipyramids, edges with two equivalent Na(1)O8 hexagonal bipyramids, edges with two equivalent Ta(2)O8 hexagonal bipyramids, and edges with four equivalent Ta(1)O7 pentagonal bipyramids. All Ta(2)-O(1) bond lengths are 2.09 Å. All Ta(2)-O(3) bond lengths are 2.10 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to one Na(1), one Ta(2), and two equivalent Ta(1) atoms to form distorted ONaTa3 trigonal pyramids that share corners with four equivalent O(2)Na2Ta2 tetrahedra, corners with eight equivalent O(1)NaTa3 trigonal pyramids, edges with two equivalent O(2)Na2Ta2 tetrahedra, and edges with two equivalent O(1)NaTa3 trigonal pyramids. In the second O site, O(2) is bonded to two equivalent Na(1) and two equivalent Ta(1) atoms to form distorted ONa2Ta2 tetrahedra that share corners with six equivalent O(2)Na2Ta2 tetrahedra, corners with eight equivalent O(1)NaTa3 trigonal pyramids,  an edgeedge with one O(2)Na2Ta2 tetrahedra, and edges with four equivalent O(1)NaTa3 trigonal pyramids. In the third O site, O(3) is bonded in a trigonal planar geometry to one Ta(1) and two equivalent Ta(2) atoms.