First-principles pressure dependent investigation of the physical properties of KB2H8: A prospective high-TC superconductor

Abstract

Using the density functional theory (DFT) based first-principles investigation, the structural, mechanical, hardness, elastic anisotropy, optoelectronic, thermophysical and superconducting properties of cubic KB2H8 have been studied within the uniform pressure range of 0–––24 GPa. The calculated structural parameters are in good agreement with the previous theoretical work. The compound KB2H8 is found to be structurally and thermodynamically stable in the pressure range from 8 GPa to 24 GPa. Single crystal elastic constants Cij and bulk elastic moduli (B, G and Y) increase systematically with pressure from 8 GPa to 24 GPa. In the stable phase, KB2H8 is moderately elastically anisotropic and ductile in nature. The compound is highly machinable and possesses high fracture resistance. The Debye temperature, melting temperature and thermal conductivity increase with increasing pressure. The results of electronic band structure calculations and optical parameters at different pressures are consistent with each other and exhibit metallic characteristics. The compound is optically isotropic. It has potential to be used as a very efficient solar energy reflector. The electronic energy density of states at the Fermi level is found to decrease systematically with increasing pressure. The same trend is found for the repulsive Coulomb pseudopotential and the electron–phonon coupling constant. Possible relevance of the studied properties to superconductivity has also been discussed in this paper.