Evidence for a new class of solids. First-principles study of K(Al-13)

The stability of the crystalline phase of a cluster-assembled solid K(Al-13) has been investigated using first-principles total energy calculations. We find that K(Al-13) may form in the CsCl structure with a lattice constant of 6.52 Angstrom. Unlike the gas phase, in which the ground state of the Al-13 cluster is icosahedral, the Al,, becomes cuboctahedral in the solid phase due to crystal field effects. The system is metallic and is stable against lattice distortions. The calculations suggest that a new metastable solid could be made from two immiscible elements through specially designed synthesis processes.