Electronic Structure of Approximant Phase to Icosahedral Ti-Transition-Metal Quasi-Crystals

We report ab initio calculations of the electronic structure of large-unit-cell approximant phases to icosahedral Ti-transition-metal quasi-crystals and of disordered alloys of the same composition. Our results demonstrate that the approximant phase is stabilized relative to the body-centred solid solution by the formation of a broad pseudogap at the Fermi level. The conditions for the formation of the pseudogap are discussed in relation to the atomic structure.