La3Ta is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to four equivalent La(1), four equivalent La(2), and four equivalent Ta(1) atoms to form distorted LaLa8Ta4 cuboctahedra that share corners with twelve equivalent La(1)La8Ta4 cuboctahedra, edges with eight equivalent La(1)La8Ta4 cuboctahedra, edges with eight equivalent La(2)La8Ta4 cuboctahedra, edges with eight equivalent Ta(1)La12 cuboctahedra, faces with four equivalent La(2)La8Ta4 cuboctahedra, faces with four equivalent Ta(1)La12 cuboctahedra, and faces with ten equivalent La(1)La8Ta4 cuboctahedra. In the second La site, La(2) is bonded to eight equivalent La(1) and four equivalent Ta(1) atoms to form distorted LaLa8Ta4 cuboctahedra that share corners with four equivalent La(2)La8Ta4 cuboctahedra, corners with eight equivalent Ta(1)La12 cuboctahedra, edges with eight equivalent La(2)La8Ta4 cuboctahedra, edges with sixteen equivalent La(1)La8Ta4 cuboctahedra, faces with four equivalent La(2)La8Ta4 cuboctahedra, faces with six equivalent Ta(1)La12 cuboctahedra, and faces with eight equivalent La(1)La8Ta4 cuboctahedra. Ta(1) is bonded to four equivalent La(2) and eight equivalent La(1) atoms to form TaLa12 cuboctahedra that share corners with four equivalent Ta(1)La12 cuboctahedra, corners with eight equivalent La(2)La8Ta4 cuboctahedra, edges with eight equivalent Ta(1)La12 cuboctahedra, edges with sixteen equivalent La(1)La8Ta4 cuboctahedra, faces with four equivalent Ta(1)La12 cuboctahedra, faces with six equivalent La(2)La8Ta4 cuboctahedra, and faces with eight equivalent La(1)La8Ta4 cuboctahedra.
La3Ta is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. There are two inequivalent La sites. In the first La site, La(1) is bonded to four equivalent La(1), four equivalent La(2), and four equivalent Ta(1) atoms to form distorted LaLa8Ta4 cuboctahedra that share corners with twelve equivalent La(1)La8Ta4 cuboctahedra, edges with eight equivalent La(1)La8Ta4 cuboctahedra, edges with eight equivalent La(2)La8Ta4 cuboctahedra, edges with eight equivalent Ta(1)La12 cuboctahedra, faces with four equivalent La(2)La8Ta4 cuboctahedra, faces with four equivalent Ta(1)La12 cuboctahedra, and faces with ten equivalent La(1)La8Ta4 cuboctahedra. All La(1)-La(1) bond lengths are 3.47 Å. All La(1)-La(2) bond lengths are 3.47 Å. All La(1)-Ta(1) bond lengths are 3.47 Å. In the second La site, La(2) is bonded to eight equivalent La(1) and four equivalent Ta(1) atoms to form distorted LaLa8Ta4 cuboctahedra that share corners with four equivalent La(2)La8Ta4 cuboctahedra, corners with eight equivalent Ta(1)La12 cuboctahedra, edges with eight equivalent La(2)La8Ta4 cuboctahedra, edges with sixteen equivalent La(1)La8Ta4 cuboctahedra, faces with four equivalent La(2)La8Ta4 cuboctahedra, faces with six equivalent Ta(1)La12 cuboctahedra, and faces with eight equivalent La(1)La8Ta4 cuboctahedra. All La(2)-Ta(1) bond lengths are 3.47 Å. Ta(1) is bonded to four equivalent La(2) and eight equivalent La(1) atoms to form TaLa12 cuboctahedra that share corners with four equivalent Ta(1)La12 cuboctahedra, corners with eight equivalent La(2)La8Ta4 cuboctahedra, edges with eight equivalent Ta(1)La12 cuboctahedra, edges with sixteen equivalent La(1)La8Ta4 cuboctahedra, faces with four equivalent Ta(1)La12 cuboctahedra, faces with six equivalent La(2)La8Ta4 cuboctahedra, and faces with eight equivalent La(1)La8Ta4 cuboctahedra.