ErTaO4 crystallizes in the monoclinic C2/c space group. Er(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. Ta(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Ta(1) atoms to form a mixture of distorted edge and corner-sharing OEr2Ta2 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Er(1) and one Ta(1) atom.
ErTaO4 crystallizes in the monoclinic C2/c space group. Er(1) is bonded in a 8-coordinate geometry to four equivalent O(1) and four equivalent O(2) atoms. There are two shorter (2.30 Å) and two longer (2.43 Å) Er(1)-O(1) bond lengths. There are two shorter (2.26 Å) and two longer (2.33 Å) Er(1)-O(2) bond lengths. Ta(1) is bonded in a 6-coordinate geometry to two equivalent O(2) and four equivalent O(1) atoms. Both Ta(1)-O(2) bond lengths are 1.87 Å. There are two shorter (1.95 Å) and two longer (2.33 Å) Ta(1)-O(1) bond lengths. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Er(1) and two equivalent Ta(1) atoms to form a mixture of distorted edge and corner-sharing OEr2Ta2 tetrahedra. In the second O site, O(2) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Er(1) and one Ta(1) atom.