Li 20 Mg 6 Cu 13 Al 42 : a new ordered quaternary superstructure to the icosahedral T ‐Mg 32 (Zn,Al) 49 phase with fullerene‐like Al 60 cluster

The new quaternary aluminide Li 20 Mg 6 Cu 13 Al 42 was synthesized from the elements in a sealed tantalum crucible. The crystal structure was studied by single crystal and confirmed by X‐ray powder diffraction. Li 20 Mg 6 Cu 13 Al 42 { cI 162, , a = 13.8451 (2), R [ F 2 > 2σ( F 2 )] = 0.023} crystallizes as an ordered version of Mg 32 (Al,Zn) 49 and Li—Cu— X ( X = Al, Ga, Si) periodic crystals containing icosahedral clusters. The Li 20 Mg 6 Cu 13 Al 42 structure can also be described as three‐shell icosahedral clusters of [CuAl 12 @Li 20 Cu 12 @Al 60 ], enclosed inside a distorted triacontahedron. The electronic structure calculations were performed by means of the TB‐LMTO‐ASA program and confirm the core–shell packing of these clusters. The isostructural compound of Li 20 Mg 6 Cu 13 Ga 42 was found in a Li–Mg–Cu–Ga quaternary system.