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

TL;DR

This study uses DFT calculations to analyze the structural, elastic, electronic, and thermal properties of the novel Hf2SeC MAX phase, revealing its stability, metallic nature, and potential for high-temperature applications.

Contribution

It provides the first comprehensive DFT-based investigation of Hf2SeC, comparing its properties with related MAX phases and explaining its high hardness and brittleness.

Findings

Hf2SeC is mechanically stable and metallic.

It exhibits higher hardness than Hf2SC due to DOS effects.

Hf2SeC shows anisotropic electronic and mechanical properties.

Abstract

The physical characteristics of the novel chalcogenide MAX phase Hf2SeC have been investigated using the DFT method. The obtained lattice constant 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 mechanical stability has been done based on Cij in accordance with the previously stated stability criteria. The reason for the higher hardness of Hf2SeC compared to Hf2SC is explained using the density of states (DOS). The brittleness character of Hf2SeC has been revealed using the Pugh ratio, Poisson ratio, and Cauchy pressure. The electronic properties (band structure and charge density mapping) of Hf2SeC are studied to disclose the metallic nature as well as bonding nature within the titled chalcogenide. The anisotropy in both electronic conductivity and mechanical properties is investigated. The temperature and pressure dependence of volume, Gr\"uneisen parameter, Debye temperature, 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 explore its suitability for high-temperature applications.