Experimental and theoretical investigations of superconducting dense alkali and alkaline-earth metal carbides*

Dense high symmetry carbon framework structures containing alkali or alkaline earth metals inside the framework are expected to exhibit interesting electronic properties such as superconductivity analogous to those found in superconducting hydrides under pressure. For example, sodalite-like NaC₆ is predicted to stabilize at high-pressure and have superconductivity above 100 K. [1] However, detailed studies of the phases in carbon-based systems are both unexplored experimentally under pressure. Here, we present high-pressure studies on M-C compounds (e.g., M = Li, Na, Mg) using a variety of techniques including x-ray diffraction and Raman spectroscopy. Stability, structure and bonding, and electronic properties are also studied using first-principles density functional theory calculations.

References:

[1] S. Lu et al., Phys. Rev. B 2016, 93 104509.

[2] Z. Liu et al., Physical Review Letters 2021, 127, 157002.

[3] K.  Sano, Y. Masuda, and H. Ito, arXiv (2020).