Exploring elastic anisotropies, mechanical, thermodynamic, optical properties and structural stability of the new possible 312 MAX phases Hf3GeX2 (X = C, N and B). Ab-initio study

In this study, we used first-principles calculations based on density functional theory to predict the structural, electronic, and thermodynamic properties of novel 312 Hf3GeX2 (X = C, N, and B) MAX phases. Our findings confirm the thermodynamic, mechanical, and dynamical stability of the MAX phases studied. Through detailed analysis, we have confirmed the metallic behavior of all compounds. Our specific insights into the directionaldependent values of Young's modulus and bulk modulus have revealed elastically anisotropic properties. Hf3GeN2 and Hf3GeB2 demonstrate ductile behavior, while Hf3GeC2 exhibits brittleness. Furthermore, we observe that the Hf3GeX2 (X = C, N, and B) MAX phases exhibit high absorption in the ultraviolet region and significant reflectivity values (above 44%) in the infrared, visible, and ultraviolet energy ranges. These materials show promise for use in optical and optoelectronic devices, as they have the potential to be used as coatings to reduce solar heating. Notably, Hf3GeB2 exhibits low thermal conductivity, positioning it as a promising material for thermal barrier coatings (TBC), while Hf3GeC2 may find utility as a thermal conductive material at room temperature.