544 / 2019-03-20 11:53:27

Structural stability, electronic structure, and superconductivity of cubic sodium hexaboride NaB6 from first-principle calculations

Structural stability; Electronic structure; Superconductor; First-principle calculations

全体主题 > High Pressure Physics and Materials Science

The metal hexaborides MB6 (M are alkali, alkaline-earth, rare-earth and early transition metals) have attracted considerable interest due to their interesting physical properties. In alkali metal hexaborides system, the structural stability of cubic sodium hexaboride NaB6 is lack of detailed research. By investigating the band structure of NaB6 simple cubic structure, NaB6 was reported to be unstable. In this work, the structural stability, electronic structure, and superconducting transition temperatures of cubic NaB6 were investigated.
The calculations of phonon dispersion spectra, formation energy, and elastic constants indicate that the cubic NaB6 is dynamically, thermodynamically, and mechanically stable, respectively. The cubic NaB6 has lower formation energy compared with the experimentally synthesized KB6 and may be prepared. The calculated band structure and PDOS demonstrate the metallicity of NaB6. The superconducting transition temperatures at the ambient pressure for NaB6 and KB6 are predicted to be 15.7 K with λ = 0.60 and 14.6 K with λ = 0.57, respectively.