Mechanical stability and superconductivity of PbO-type phase of thorium monocarbide at high pressure

Abstract

As a potential nuclear fuel for the next generation of nuclear reactors, the structural and physical properties of thorium monocarbide (ThC) under high pressure have attracted a wide range of research interest. Here, the mechanical, electronic, dynamical, and superconducting properties of PbO-type ThC have been systematically investigated through first-principles calculations, which established the thermodynamic and mechanical stability of this phase within the pressure range of 60–140GPa. Moreover, it is found that pressure significantly affected the electronic states near the Fermi level and superconductivity. The superconducting transition temperature Tc first increases, and then decreases with increasing pressure. The maximal value of Tc reaches 4.64K at 80GPa. This phenomenon is a representation of the reconstruction of the Fermi surface and phonon hardening under compression.