U3Gd is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to four equivalent U(1), four equivalent U(2), and four equivalent Gd(1) atoms to form UGd4U8 cuboctahedra that share corners with twelve equivalent U(1)Gd4U8 cuboctahedra, edges with eight equivalent U(1)Gd4U8 cuboctahedra, edges with eight equivalent U(2)Gd4U8 cuboctahedra, edges with eight equivalent Gd(1)U12 cuboctahedra, faces with four equivalent U(2)Gd4U8 cuboctahedra, faces with four equivalent Gd(1)U12 cuboctahedra, and faces with ten equivalent U(1)Gd4U8 cuboctahedra. In the second U site, U(2) is bonded to eight equivalent U(1) and four equivalent Gd(1) atoms to form distorted UGd4U8 cuboctahedra that share corners with four equivalent U(2)Gd4U8 cuboctahedra, corners with eight equivalent Gd(1)U12 cuboctahedra, edges with eight equivalent U(2)Gd4U8 cuboctahedra, edges with sixteen equivalent U(1)Gd4U8 cuboctahedra, faces with four equivalent U(2)Gd4U8 cuboctahedra, faces with six equivalent Gd(1)U12 cuboctahedra, and faces with eight equivalent U(1)Gd4U8 cuboctahedra. Gd(1) is bonded to four equivalent U(2) and eight equivalent U(1) atoms to form GdU12 cuboctahedra that share corners with four equivalent Gd(1)U12 cuboctahedra, corners with eight equivalent U(2)Gd4U8 cuboctahedra, edges with eight equivalent Gd(1)U12 cuboctahedra, edges with sixteen equivalent U(1)Gd4U8 cuboctahedra, faces with four equivalent Gd(1)U12 cuboctahedra, faces with six equivalent U(2)Gd4U8 cuboctahedra, and faces with eight equivalent U(1)Gd4U8 cuboctahedra.
U3Gd is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent U sites. In the first U site, U(1) is bonded to four equivalent U(1), four equivalent U(2), and four equivalent Gd(1) atoms to form UGd4U8 cuboctahedra that share corners with twelve equivalent U(1)Gd4U8 cuboctahedra, edges with eight equivalent U(1)Gd4U8 cuboctahedra, edges with eight equivalent U(2)Gd4U8 cuboctahedra, edges with eight equivalent Gd(1)U12 cuboctahedra, faces with four equivalent U(2)Gd4U8 cuboctahedra, faces with four equivalent Gd(1)U12 cuboctahedra, and faces with ten equivalent U(1)Gd4U8 cuboctahedra. All U(1)-U(1) bond lengths are 3.09 Å. All U(1)-U(2) bond lengths are 3.25 Å. All U(1)-Gd(1) bond lengths are 3.25 Å. In the second U site, U(2) is bonded to eight equivalent U(1) and four equivalent Gd(1) atoms to form distorted UGd4U8 cuboctahedra that share corners with four equivalent U(2)Gd4U8 cuboctahedra, corners with eight equivalent Gd(1)U12 cuboctahedra, edges with eight equivalent U(2)Gd4U8 cuboctahedra, edges with sixteen equivalent U(1)Gd4U8 cuboctahedra, faces with four equivalent U(2)Gd4U8 cuboctahedra, faces with six equivalent Gd(1)U12 cuboctahedra, and faces with eight equivalent U(1)Gd4U8 cuboctahedra. All U(2)-Gd(1) bond lengths are 3.09 Å. Gd(1) is bonded to four equivalent U(2) and eight equivalent U(1) atoms to form GdU12 cuboctahedra that share corners with four equivalent Gd(1)U12 cuboctahedra, corners with eight equivalent U(2)Gd4U8 cuboctahedra, edges with eight equivalent Gd(1)U12 cuboctahedra, edges with sixteen equivalent U(1)Gd4U8 cuboctahedra, faces with four equivalent Gd(1)U12 cuboctahedra, faces with six equivalent U(2)Gd4U8 cuboctahedra, and faces with eight equivalent U(1)Gd4U8 cuboctahedra.