A computational screening of Ta–Sb intermetallics at high pressure

Abstract

The binary high-pressure phase diagram of the Ta–Sb system was constructed for the first time in this study, utilizing the evolutionary algorithm USPEX and density functional theory (DFT). Ten pressurized dynamically and mechanically stable or metastable novel phases of Ta–Sb were discovered, including I4/mmm-TaSb2, P4/nmm-TaSb, P-3-Ta2Sb7, I4/mmm-Ta2Sb3, P-4m2-Ta7Sb, Pm-3-Ta7Sb, Pmm2-Ta15Sb, P4/nmm-TaSb3, I4/mmm-Ta3Sb4, and I4/mmm-Ta2Sb5. The compounds P-4m2-Ta7Sb and Pmm2-Ta15Sb exhibit promising characteristics as non-centrosymmetric superconductors (NCSs), with their superconducting critical temperature (TC) being 3.831 and 3.221 K, respectively. The application of pressure tuning is predicted to transform the topological characteristics of P4/nmm-TaSb, causing it to transition from a topological insulator state to a Dirac semimetal state and ultimately reverting back to a topological insulator state. Therefore, the P4/nmm-TaSb compound is considered a promising candidate to investigate topological and superconducting excitations. Moreover, the mechanical and thermal properties of Ta–Sb binary phases were also investigated. The thermal conductivity of I4/mmm-TaSb2, P4/nmm-TaSb, and P4/nmm-TaSb3 all surpasses 20 W m−1 K−1 at 1000 K, showcasing their excellent thermal conductivity properties. The present study addresses the research gap concerning high-pressure structures in the Ta–Sb binary system, thereby offering valuable insights for the design and development of intermetallic compounds within this binary system.