Pressure-stabilized superconducting electride Li5C

The search for electrides has recently attracted great interest owing to their unique physical properties, such as superconductivity. Li5C has been proposed as a candidate electride with a high superconducting critical temperature T-c of 48 K originating mainly from the localized electrons. Here, a combination of structure searches and first-principles calculations has been performed to acquire the phase diagrams of a Li-C system at high pressure. The structure searches unraveled four successive structures under pressure for Li5C that are energetically more stable than the previously proposed superconducting one. The dimension of the localized electrons in Li5C decreases under compression due to the reduced interstitial voids. Electron-phonon calculations demonstrated that the four Li5C phases are superconductors with a maximum T-c of 5.7 K, excluding its possibility of high superconductivity. Analysis showed that the host hybridized electrons, instead of interstitial electrons, contribute mainly to the superconductivity in Li5C.

Automated summary

The phase diagrams of the Li-C system under high pressure were obtained through a combination of structure searches and first-principles calculations. The dimension of localized electrons in Li5C decreases under compression, resulting in its superconductivity. Analysis showed that the superconductivity in Li5C mainly originates from the host hybridized electrons instead of interstitial electrons.