Unveiling mechanical, electronic, and optical properties of newly synthesized Mo2VAlC2 and Mo2V2AlC3 o-MAX phases via first-principles calculations

Abstract

Mo-based out-of-plane-ordered MAX (o-MAX) phases have drawn considerable attention owing to their unique structural, mechanical, electronic, thermal, and optical properties , making them promising candidates for diverse advanced applications. First-principles calculations were carried out using the DFT approach to investigate the newly synthesized o-MAX phases Mo 2 VAlC 2 and Mo 2 V 2 AlC 3 . The geometrically optimized parameters we calculated matched the experimental findings well, which enhanced their reliability. Calculating elastic constants validates mechanical stability while combining Poisson's and Pugh's ratios characterizes brittleness . The compounds have very high elastic anisotropy due to their layered structures. Electronic structure analysis reveals a mix of bonding characteristics, with a predominant contribution from covalent bonding. A high Debye temperature of 657 K for Mo 2 VAlC 2 and 706 K for Mo 2 V 2 AlC 3 indicates strong atomic bonding and a stable lattice structure. The analysis of melting point and minimum thermal conductivity suggested that these materials are appropriate for use in high-temperature conditions. Both phases exhibit metallic conductivity, but Mo 2 V 2 AlC 3 has a higher electron density at the Fermi level due to its greater vanadium elements. The study of optical properties revealed the potential use of these o-MAX phases as a coating to lessen solar heating. These findings encourage further experimental and theoretical investigations of Mo-based o-MAX phases to exploit their versatile properties and expand their application scope fully.

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