ErNd3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Er(1) is bonded to twelve equivalent Nd(1) atoms to form ErNd12 cuboctahedra that share corners with six equivalent Er(1)Nd12 cuboctahedra, corners with twelve equivalent Nd(1)Nd8Er4 cuboctahedra, edges with eighteen equivalent Nd(1)Nd8Er4 cuboctahedra, faces with eight equivalent Er(1)Nd12 cuboctahedra, and faces with twelve equivalent Nd(1)Nd8Er4 cuboctahedra. Nd(1) is bonded to four equivalent Er(1) and eight equivalent Nd(1) atoms to form NdNd8Er4 cuboctahedra that share corners with four equivalent Er(1)Nd12 cuboctahedra, corners with fourteen equivalent Nd(1)Nd8Er4 cuboctahedra, edges with six equivalent Er(1)Nd12 cuboctahedra, edges with twelve equivalent Nd(1)Nd8Er4 cuboctahedra, faces with four equivalent Er(1)Nd12 cuboctahedra, and faces with sixteen equivalent Nd(1)Nd8Er4 cuboctahedra.
ErNd3 is beta Cu3Ti-like structured and crystallizes in the hexagonal P6_3/mmc space group. Er(1) is bonded to twelve equivalent Nd(1) atoms to form ErNd12 cuboctahedra that share corners with six equivalent Er(1)Nd12 cuboctahedra, corners with twelve equivalent Nd(1)Nd8Er4 cuboctahedra, edges with eighteen equivalent Nd(1)Nd8Er4 cuboctahedra, faces with eight equivalent Er(1)Nd12 cuboctahedra, and faces with twelve equivalent Nd(1)Nd8Er4 cuboctahedra. There are six shorter (3.62 Å) and six longer (3.71 Å) Er(1)-Nd(1) bond lengths. Nd(1) is bonded to four equivalent Er(1) and eight equivalent Nd(1) atoms to form NdNd8Er4 cuboctahedra that share corners with four equivalent Er(1)Nd12 cuboctahedra, corners with fourteen equivalent Nd(1)Nd8Er4 cuboctahedra, edges with six equivalent Er(1)Nd12 cuboctahedra, edges with twelve equivalent Nd(1)Nd8Er4 cuboctahedra, faces with four equivalent Er(1)Nd12 cuboctahedra, and faces with sixteen equivalent Nd(1)Nd8Er4 cuboctahedra. There are a spread of Nd(1)-Nd(1) bond distances ranging from 3.64-3.75 Å.