Atomic distributions of Ag and In in the γ-brass type Ag9In4

The γ-brass type phase Ag9In4 in the binary Ag–In system has been synthesized by high-temperature method and, the crystal structure has been determined by the means of X-ray diffraction techniques and energy dispersive X-ray spectroscopy. The structure crystallizes in the primitive cubic space group P4‾3m (cP52) with a cell parameter of ∼ 9.89 Å. The unit cell contains 52 atoms distributed over 8 crystallographically independent positions. Due to weak X-ray scattering contrast between Ag and In, first principle DFT calculations have been carried out to determine the accurate site occupancy pattern of Ag and In in the structure of Ag9In4. The structure can be viewed in terms of two symmetrically inequivalent 26-atom γ-clusters (Ag22In4 and Ag14In12). The density of state (DOS) curve shows a pseudogap near the Fermi level, which endorses the phase stability by Hume-Rothery mechanism due to interaction between the Fermi surface and the Brillouin zone (FS-BZ). Bonding analysis shows that Ag–In contact has the highest contribution in stabilizing the titled phase.