Structural, electronic, mechanical, thermal, and optical properties of UIr3 under pressure: A comprehensive DFT study

Abstract

First-principles density functional theory calculations were performed to assess the pressure effect on structural, electronic, mechanical, thermal, and optical properties of cubic intermetallic UIr3. The calculated lattice parameter deviates from the experimental value by 0.40%, indicating the reliability of the present study. The obtained lattice constant decreases at a constant rate with pressure over the entire pressure range. The band structure and Fermi surface disclose the metallic nature of UIr3. The external pressure suppresses the overlapping between the valence and conduction bands and reduces the total density of state at the Fermi level. The pseudogap moves to the left from the Fermi level with increasing pressure, which indicates a decrease in the structural stability of UIr3. Peaks in the valence band move toward deeper energy positions when the external pressure is increased from 0 to 25 GPa, indicating the increase in the covalency of UIr3. Contour maps of charge density and Mulliken population analysis imply that UIr3 has also partial ionic and covalent nature in chemical bonding. In the considered pressure range, UIr3 maintains its mechanical and dynamical stability as well as ductility and machinability. The elastic anisotropic level of UIr3 increases slightly with fluctuations above the pressure of 5 GPa. Shape change in UIr3 will be more difficult due to the increase in shear modulus and microhardness under the external pressure. Thermal properties of UIr3 are favorable for being a promising thermal barrier coating material, and optical reflectivity makes it a potential candidate material for coating to diminish solar heating.