BiErO3 is Ilmenite-like structured and crystallizes in the trigonal R3c space group. Er(1) is bonded to six equivalent O(1) atoms to form distorted ErO6 octahedra that share corners with three equivalent Bi(1)O6 octahedra, corners with six equivalent Er(1)O6 octahedra, edges with three equivalent Bi(1)O6 octahedra, and  a faceface with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-69°. Bi(1) is bonded to six equivalent O(1) atoms to form distorted BiO6 octahedra that share corners with three equivalent Er(1)O6 octahedra, corners with six equivalent Bi(1)O6 octahedra, edges with three equivalent Er(1)O6 octahedra, and  a faceface with one Er(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-69°. O(1) is bonded in a distorted see-saw-like geometry to two equivalent Er(1) and two equivalent Bi(1) atoms.
BiErO3 is Ilmenite-like structured and crystallizes in the trigonal R3c space group. Er(1) is bonded to six equivalent O(1) atoms to form distorted ErO6 octahedra that share corners with three equivalent Bi(1)O6 octahedra, corners with six equivalent Er(1)O6 octahedra, edges with three equivalent Bi(1)O6 octahedra, and  a faceface with one Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 39-69°. There are three shorter (2.22 Å) and three longer (2.34 Å) Er(1)-O(1) bond lengths. Bi(1) is bonded to six equivalent O(1) atoms to form distorted BiO6 octahedra that share corners with three equivalent Er(1)O6 octahedra, corners with six equivalent Bi(1)O6 octahedra, edges with three equivalent Er(1)O6 octahedra, and  a faceface with one Er(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 56-69°. There are three shorter (2.33 Å) and three longer (2.53 Å) Bi(1)-O(1) bond lengths. O(1) is bonded in a distorted see-saw-like geometry to two equivalent Er(1) and two equivalent Bi(1) atoms.