Be2Ta2O5 crystallizes in the tetragonal P4/mmm space group. Be(1) is bonded to one O(2) and four equivalent O(1) atoms to form distorted BeO5 square pyramids that share corners with five equivalent Be(1)O5 square pyramids and faces with four equivalent Ta(2)O12 cuboctahedra. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. In the second Ta site, Ta(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form TaO12 cuboctahedra that share corners with four equivalent Ta(2)O12 cuboctahedra, faces with four equivalent Ta(2)O12 cuboctahedra, and faces with eight equivalent Be(1)O5 square pyramids. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Be(1), two equivalent Ta(1), and two equivalent Ta(2) atoms. In the second O site, O(2) is bonded in a linear geometry to two equivalent Be(1) and four equivalent Ta(2) atoms.
Be2Ta2O5 crystallizes in the tetragonal P4/mmm space group. Be(1) is bonded to one O(2) and four equivalent O(1) atoms to form distorted BeO5 square pyramids that share corners with five equivalent Be(1)O5 square pyramids and faces with four equivalent Ta(2)O12 cuboctahedra. The Be(1)-O(2) bond length is 1.58 Å. All Be(1)-O(1) bond lengths are 1.80 Å. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a body-centered cubic geometry to eight equivalent O(1) atoms. All Ta(1)-O(1) bond lengths are 2.19 Å. In the second Ta site, Ta(2) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form TaO12 cuboctahedra that share corners with four equivalent Ta(2)O12 cuboctahedra, faces with four equivalent Ta(2)O12 cuboctahedra, and faces with eight equivalent Be(1)O5 square pyramids. All Ta(2)-O(2) bond lengths are 2.50 Å. All Ta(2)-O(1) bond lengths are 2.61 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 6-coordinate geometry to two equivalent Be(1), two equivalent Ta(1), and two equivalent Ta(2) atoms. In the second O site, O(2) is bonded in a linear geometry to two equivalent Be(1) and four equivalent Ta(2) atoms.