• Hexagonal MAC (M = Ti, Zr, Hf; A = Be, B) carbides are stable, metallic, and mechanically robust, ideal for extreme environments. • TiBeC has the highest thermal conductivity (207 Wm -1 K −1 ), while TiBC shows the highest melting point (2783 K). • TiBeC is the hardest, while HfBC is ductile, unlike other brittle MAC compounds. • MAC carbides exhibit strong UV optics, making them promising for optoelectronics. • First computational study on MAC thermophysical and optical properties, guiding future experiments. The hexagonal-structured carbides, MAC (M = Ti, Zr, Hf; A = Be, B), were designed for advanced technological applications using density functional theory (DFT) calculations within the generalized gradient approximation (GGA) employing the Perdew–Burke–Ernzerhof (PBE) functional. To explore the potential future implications of these compounds, their structural, electronic, elastic, magnetic, mechanical, thermophysical, phonon, anisotropic, and optical characteristics were systematically analyzed. The calculated structural parameters align well with existing data from the literature. All the studied MAC compounds are metallic in nature (E g = 0 eV) and exhibit non-magnetic behavior, with a magnetic moment of 0 μ B /f.u. They demonstrate comprehensive stability, including optimized crystal structures, dynamical stability evidenced by the absence of imaginary phonon modes, mechanical stability satisfying Born’s criteria, negative formation energies indicating thermodynamic favorability, and favorable thermodynamic properties supporting their overall robustness. For the first time, this study investigated the thermal and optoelectronic properties of MAC (M = Ti, Zr, Hf; A = Be, B) compounds. Among the materials analyzed, TiBeC demonstrated the highest Debye temperature (1117 K) and lattice thermal conductivity (207 Wm −1 K −1 ), while TiBC exhibited the highest melting temperature, reaching 2783 K. All the materials demonstrate elastic anisotropy and exhibit exceptional mechanical hardness. The hardness decreases in the order: TiBeC > ZrBeC > HfBeC > ZrBC > TiBC > HfBC, whereas the machinability index exhibits an inverse trend, increasing in the opposite direction. The HfBC exhibits ductile behavior, as indicated by its Pugh’s ratio (1.83) and Poisson’s ratio (0.269), whereas the remaining MAC compounds possess a brittle nature. The calculated zero-point energies follow the same trend as the free energies. Among the studied compounds, TiBC has the highest zero-point energy (0.5789 eV), while HfBC possesses the lowest (0.4626 eV). These results underscore the suitability of MAC compounds as advanced materials for nuclear reactors in NPPs, presenting significant potential for enhancing reactor safety and performance. In the field of optics, a frequency-dependent analysis indicates that hexagonal MAC exhibits significant potential for optoelectronic applications, especially within the ultraviolet (UV) energy spectrum. This study provides a comprehensive understanding of the key physical properties of MAC (M = Ti, Zr, Hf; A = Be, B) carbides, laying a computational foundation for future experimental research and real-world applications.
Islam et al. (Sun,) studied this question.