Exploring the Multifunctional Properties of MC ₂ B ₂ (M = Lu, La) Structures Using Density Functional Theory

Abstract This study compiles the structural, mechanical, bonding, and dynamical characteristics of the recently synthesized rare earth metallic compounds MC 2 B 2 (M = Lu, La) by means of density functional theory (DFT). Both LuC 2 B 2 and LaC 2 B 2 crystallize in tetragonal symmetry. The negative cohesive energy of LuC 2 B 2 (−7.824 eV atom −1 ) and LaC 2 B 2 (−7.692 eV atom −1 ) ensured the stability of both compounds. The compounds exhibit mechanical stability with significant elastic anisotropy, ductility, and high hardness (22.84 and 21.84 GPa for LuC 2 B 2 and LaC 2 B 2 , respectively). The electronic band structures and density of states (DOS) indicate metallic behavior, predominantly influenced by Lu/La‐5d, B‐2p, and C‐2p states, showing mixed bonding characteristics with ionic and covalent contributions. Both compounds are hard and brittle in nature. Possessing a high melting point (2183.06 K for LuC 2 B 2 and 1873.82 K for LaC 2 B 2 ), the compounds are suitable for applications in thermally harsh conditions. Through Drude‐like low‐energy behavior, optical properties also confirmed metallic nature and showed significant reflection and absorption with a specific directional dependence, especially LuC 2 B 2 shows exceptional reflectivity (≈80%) in the infrared (IR) to lower upper ultraviolet (UV) regions. The findings collectively demonstrate that LuC 2 B 2 and LaC 2 B 2 are viable options for cutting‐edge technological applications that demand superior optoelectronic, thermophysical, and mechanical performance.