Mechanical, vibration, and optical properties of IrAl intermetallic compound via DFT calculations: high-pressure effect

Abstract

In this study, the effect of pressure on the structural, elastic, anisotropy, electronic, phonon, and optical properties of the IrAl compound in B2 structure was investigated by the first-principles method. The lattice constant, volume, density, and bulk modulus parameters were compared with theoretical and experimental data at zero pressure, and their variations with pressure effect were also examined. The IrAl compound fullfills the Born criteria at all pressure values, indicating structural stability, as no instability is observed even with increasing pressure. The compound exhibits ductile properties according to Paugh ratio (B/G), Cauchy pressure (C12–C44, C’), and Poisson ratio (λ) criteria. Electronically metallic in nature, it has maintained this nature with pressure variation. The absence of negative frequencies in the phonon dispersion curve explains that the compound is dynamically stable. Mulliken Atom Populations analysis was used to understand the bond properties between Ir-Al atoms, focusing on charge transfer and ionicity. The complex dielectric function was employed to determine the optical properties and evaluate their variations under pressure. Finally, the effect of pressure on the physical and electronic properties of the IrAl compound useful for coating applications were evaluated.