DFT insights into the new Hf-based chalcogenide MAX phase Hf2SeC

Abstract

The physical characteristics of the novel chalcogenide MAX phase Hf2SeC have been investigated using the DFT method. The obtained lattice constants and elastic constants (Cij) are compared with previous results to check the consistency of our setting parameters during calculations. Moreover, the elastic properties such as elastic constants, moduli, anisotropy, and hardness are also compared with preexisting MAX phases of its kind. The checking of the dynamical and mechanical stability have been done based on the phonon dispersions and elastic constants. The reason for the higher hardness of Hf2SeC compared to Hf2SC is explained using the density of states (DOS). The brittleness of Hf2SeC has been revealed using the Pugh ratio, Poisson's ratio, and Cauchy pressure. The electronic properties (band structure and charge density mapping) of Hf2SeC disclosed its metallic nature and bonding behavior. The anisotropy in both electronic conductivity and mechanical properties are investigated. The temperature and pressure dependence of volume, Grüneisen parameter (γ), Debye temperature (ΘD), thermal expansion coefficient (TEC), and specific heat at constant volume (Cv) are explored. In addition, minimum thermal conductivity (Kmin) and melting point (Tm) are studied to investigate its suitability for high-temperature applications.