Np3Er is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. Np(1) is bonded to eight equivalent Np(1) and four equivalent Er(1) atoms to form NpEr4Np8 cuboctahedra that share corners with twelve equivalent Np(1)Er4Np8 cuboctahedra, edges with eight equivalent Er(1)Np12 cuboctahedra, edges with sixteen equivalent Np(1)Er4Np8 cuboctahedra, faces with four equivalent Er(1)Np12 cuboctahedra, and faces with fourteen equivalent Np(1)Er4Np8 cuboctahedra. Er(1) is bonded to twelve equivalent Np(1) atoms to form ErNp12 cuboctahedra that share corners with twelve equivalent Er(1)Np12 cuboctahedra, edges with twenty-four equivalent Np(1)Er4Np8 cuboctahedra, faces with six equivalent Er(1)Np12 cuboctahedra, and faces with twelve equivalent Np(1)Er4Np8 cuboctahedra.
Np3Er is Uranium Silicide structured and crystallizes in the cubic Pm-3m space group. Np(1) is bonded to eight equivalent Np(1) and four equivalent Er(1) atoms to form NpEr4Np8 cuboctahedra that share corners with twelve equivalent Np(1)Er4Np8 cuboctahedra, edges with eight equivalent Er(1)Np12 cuboctahedra, edges with sixteen equivalent Np(1)Er4Np8 cuboctahedra, faces with four equivalent Er(1)Np12 cuboctahedra, and faces with fourteen equivalent Np(1)Er4Np8 cuboctahedra. All Np(1)-Np(1) bond lengths are 3.32 Å. All Np(1)-Er(1) bond lengths are 3.32 Å. Er(1) is bonded to twelve equivalent Np(1) atoms to form ErNp12 cuboctahedra that share corners with twelve equivalent Er(1)Np12 cuboctahedra, edges with twenty-four equivalent Np(1)Er4Np8 cuboctahedra, faces with six equivalent Er(1)Np12 cuboctahedra, and faces with twelve equivalent Np(1)Er4Np8 cuboctahedra.