Computational Design of M ₄ GaC ₃ (M = V, Nb, Ta) MAX‐Phases: Stability, Mechanical Strength, and Optical Response Under High Pressure and Temperature

Abstract MAX phases, which combine metallic and ceramic characteristics, are promising candidates for operation in extreme environments owing to their exceptional structural and functional versatility. This study employs first principles density functional theory (DFT) to investigate the stability, mechanical anisotropy, and optical response of the novel M 4 GaC 3 (M = V, Nb, and Ta) MAX‐phases. All three compounds are confirmed to be thermodynamically and mechanically stable. A key finding is their outstanding performance, exhibiting ultra‐high stiffness and strong thermal resilience, which establishes their suitability for extreme thermomechanical conditions. Electronic structure analysis confirms metallic conductivity, while the optical spectra reveal high reflectivity in the visible and infrared ranges. These first‐principles predictions provide critical design insights, identifying the M 4 GaC 3 family as promising multifunctional materials for structural and functional roles in aerospace and high‐performance energy systems.