Matter and Radiation at Extremes, Volume. 8, Issue 5, 058404(2023)

A fresh class of superconducting and hard pentaborides

Hui Xie1、*, Hong Wang1, Fang Qin1, Wei Han1, Suxin Wang1, Youchun Wang2, Fubo Tian3, and Defang Duan3
Author Affiliations
  • 1College of Physics and Electronic Engineering, Hebei Normal University for Nationalities, Chengde 067000, China
  • 2College of Physics and Electronic Engineering, Linyi University, Linyi 276000, China
  • 3College of Physics, Jilin University, Changchun 130012, China
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    Figures & Tables(5)
    (a) Enthalpies of formation of predicted YB2–12 as functions of B concentration at 1 atm, 50 GPa, and 100 GPa. Open, half-filled, and filled symbols represent unstable, metastable, and stable stoichiometries, respectively, relative to the elementary substance. (b) Crystal structures of P4/mmm–YB5. (c) The B20 unit. Y and B atoms are presented as golden and green spheres. The cutoff distance between B–B bonds is 2.0 Å.
    Calculated electronic projected DOS for P4/mmm-MB5 (M = Li, Na, K, Rb, Ca, Sr, Ba, Sc, and Y) at 1 atm. The black line where the energy is equal to zero is the Fermi level.
    Eliashberg spectral function α2F(ω), EPC parameter λ(ω), and PHDOS of MB5 at 1 atm.
    • Table 1. Calculated EPC parameter λ, logarithmic average phonon frequency ωlog, electronic DOS at the Fermi level N(Ef), and superconducting transition temperature Tc of P4/mmm-MB5, with a Coulomb pseudopotential μ* = 0.1 at 1 atm.

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      Table 1. Calculated EPC parameter λ, logarithmic average phonon frequency ωlog, electronic DOS at the Fermi level N(Ef), and superconducting transition temperature Tc of P4/mmm-MB5, with a Coulomb pseudopotential μ* = 0.1 at 1 atm.

      BorideλωlogN(Ef) (states Ry−1 f.u.−1)Tc (K)
      NaB50.73454.34.9417.5
      KB50.64535.65.0514.7
      RbB50.78420.05.0718.6
      CaB50.49604.75.156.6
      SrB50.50574.95.216.8
      BaB50.73420.46.0716.3
      ScB50.90242.17.5114.2
      YB50.66403.85.6712.3
    • Table 2. Calculated elastic constants Cij (GPa) and derived bulk modulus B (GPa), shear modulus G (GPa), Young’s modulus Y (GPa), Poisson’s ratio ν, and hardness Hv (GPa) at ambient pressure. The elastic constants of all the MB5 compounds satisfy the mechanical stability criterion.52

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      Table 2. Calculated elastic constants Cij (GPa) and derived bulk modulus B (GPa), shear modulus G (GPa), Young’s modulus Y (GPa), Poisson’s ratio ν, and hardness Hv (GPa) at ambient pressure. The elastic constants of all the MB5 compounds satisfy the mechanical stability criterion.52

      BoridesC11C33C44C66C12C13BGYνHv
      NaB5421.2398.674.9113.6112.98.11651172840.2118.7
      KB5424.4331.7125.41815330.31551553840.1335.1
      RbB5340.5323.7119.1177.285.524.31411393140.1332.4
      CaB5541.1415.7107.8158.151.515.81831593700.1630.0
      SrB5504.7347.7116.5193.746.633.91731623700.1433.1
      BaB5399.5330.1133.4207.492.240.21621563550.1433.8
      ScB5530.843353.8100.6107.352.72111082760.2811.1
      YB5564.2375.259.6162.578.749.72021233070.2515.8
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    Hui Xie, Hong Wang, Fang Qin, Wei Han, Suxin Wang, Youchun Wang, Fubo Tian, Defang Duan. A fresh class of superconducting and hard pentaborides[J]. Matter and Radiation at Extremes, 2023, 8(5): 058404

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    Paper Information

    Category: High Pressure Physics and Materials Science

    Received: May. 6, 2023

    Accepted: Aug. 10, 2023

    Published Online: Nov. 21, 2023

    The Author Email: Hui Xie (huixie@hbun.edu.cn)

    DOI:10.1063/5.0157250

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