Elastic, electronic, optical, and thermodynamic properties of M2SeC (M = Hf, Zr) under high pressure

Abstract

The physical properties of the synthesized MAX phases M2SeC (M = Hf, Zr) have been investigated for the first time using the DFT method in the pressure range 0–25 GPa. The computed lattice parameters are consistent with the earlier findings at ambient pressure. The electronic band structure and energy dependent density of states reveal the metallic nature of the titled compounds. The metallic behavior of M2SeC (M = Hf, Zr) remains unchanged within the studied pressure range. Possible changes in the mechanical properties between Hf2SeC and Zr2SeC are revealed by analyzing the peaks in the density of states (DOS) for both compounds. Partial DOS is also considered under different pressures. The studied compounds remain mechanically stable up to 25 GPa. Both Hf2SeC and Zr2SeC are elastically anisotropic and brittle, but as the pressure increases up to 25 GPa, the brittleness of the materials decreases. At 5 and 10 GPa, however, both compounds exhibit a ductile behavior. The optical properties of Hf2SeC have been computed for the first time and compared with those of Zr2SeC. The investigated compounds are promising as solar heat reflectors due to their higher reflectivity in the low energy state. Different thermal properties, such as Debye temperature, melting temperature, and minimum thermal conductivity, have been explored within the studied pressure range to recognize their suitability for high-temperature applications. Both Hf2SeC and Zr2SeC have the potential to be used as coating materials for thermal barriers, although Hf2SeC is a better option.