Pressure-stabilized superconducting electride <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mrow><mml:mi>Li</mml:mi></mml:mrow><mml:mn>5</mml:mn></mml:msub><mml:mi mathvariant="normal">C</mml:mi></mml:math>
Qinfang Wang, Wenwen Cui, Kun Gao, Ju Chen, Tingting Gu, Meixu Liu, Jian Hao, Jingming Shi, Yinwei Li
Abstract
The search for electrides has recently attracted great interest owing to their unique physical properties, such as superconductivity. ${\mathrm{Li}}_{5}\mathrm{C}$ has been proposed as a candidate electride with a high superconducting critical temperature ${T}_{\text{c}}$ 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 ${\mathrm{Li}}_{5}\mathrm{C}$ that are energetically more stable than the previously proposed superconducting one. The dimension of the localized electrons in ${\mathrm{Li}}_{5}\mathrm{C}$ decreases under compression due to the reduced interstitial voids. Electron-phonon calculations demonstrated that the four ${\mathrm{Li}}_{5}\mathrm{C}$ phases are superconductors with a maximum ${T}_{\text{c}}$ 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 ${\mathrm{Li}}_{5}\mathrm{C}$.