First-principles calculations of M2SB (M = Hf, Zr and Nb) under high pressure

Abstract

This study systematically investigates the high-pressure behaviour of MAX-phase borides M₂SB (M = Zr, Hf, Nb) through first-principles calculations. The results reveal that applied pressure (0–40 GPa) significantly enhances material conductivity and mechanical strength, while maintaining dynamic stability, as evidenced by phonon dispersion analysis. Among the three compounds, Nb₂SB demonstrates superior mechanical and thermodynamic stability based on evaluations of Young's modulus and Debye temperature. Electronic structure analysis confirms their metallic nature, with pressurisation-induced anisotropy observed in 3D surface structures. Notably, Zr₂SB exhibits exceptional structural robustness under varying pressures, and the correlation between pressure-dependent B/G ratio, Poisson's ratio, and material brittleness provides critical insights for designing high-pressure-resistant boride materials.