First-principles pressure dependent investigation of the physical properties of KB2H8: A prospective high-TC superconductor
Md Ashraful Alam, F. Parvin, S. H. Naqib
Abstract
• Pressure dependent structural, thermal, optoelectronic, and superconducting state features of KB 2 H 8 are explored. • The stability conditions are explored showing clear signs of structural instability at pressures below 8 GPa. • Study of mechanical properties shows ductility, high machinability, and moderate hardness. • The compound has very high reflectivity for the visible light and high absorbance of UV light. • TDOS at the Fermi level, Coulomb pseudopotential, and T C decrease with increasing pressure. Using the density functional theory (DFT) based first-principles investigation, the structural, mechanical, hardness, elastic anisotropy, optoelectronic, thermophysical and superconducting properties of cubic KB 2 H 8 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 KB 2 H 8 is found to be structurally and thermodynamically stable in the pressure range from 8 GPa to 24 GPa. Single crystal elastic constants C ij and bulk elastic moduli ( B , G and Y ) increase systematically with pressure from 8 GPa to 24 GPa. In the stable phase, KB 2 H 8 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.