Understanding and predicting high-T_c superconductivity in metal borocarbides

A delithiated form of the bulk LiBC material comprised of honeycomb BC layers was long predicted to superconduct at 100 K. After two decades, Li_xBC has never been observed to superconduct despite extensive experimental effort. This work investigates a range of disordered Li_xBC morphologies to explain the superconductivity suppression in this compound. We propose that Li_xBC re-intercalation with select alkali and alkaline earth metals could lead to synthesis of otherwise inaccessible metastable Li_xM_yBC superconductors. According to our anisotropic Migdal-Eliashberg calculations, the quaternary compounds could have critical temperatures above 50 K.