Simple metal binary phases based on the body centered cubic structure: Electronic origin of distortions and superlattices

Binary alloy phases of the noble metals with the main group elements are analyzed in relation to the body centered cubic structure with distortions, vacancies and superlattices. The stability of these distorted phases is studied in terms of the Fermi sphere–Brillouin–Jones zone interaction within the nearly free-electron model in order to understand the importance of the band structure energy contribution to the overall crystal energy. Examination of Brillouin–Jones zone configurations with respect to the Fermi sphere for several representative phases has shown how significant the electron energy contribution is in forming the distorted structures with superlattices and ordered vacancies. This approach may be useful for understanding the complex structures recently found in compressed simple alkali metals.

► We consider complex binary phases of simple metals related to the body centered structures.
► Crystal structure of these phases is shown to be stabilized due to electron band structure energy.
► We analyze Fermi sphere–Brillouin zone configurations within the Hume-Rothery mechanism.
► This approach may be useful in understanding complex phases found in compressed alkali metals.