Predicted superconductivity in one-dimensional A3Hf2B3-type electrides.

Abstract

Inorganic electrides are considered potential superconductors due to the unique properties of their anionic electrons. However, most electrides require external high-pressure conditions to exhibit considerable superconducting transition temperatures (Tc). Therefore, searching for superconducting electrides under low or moderate external pressures is of significant research interest and importance. In this work, a series of A3Hf2B3-type compounds (A = Mg, Ca, Sr, Ba; B = Si, Ge, Sn, Pb) were constructed and systematically studied based on density functional theory calculations. According to the analysis of the electronic structures and phonon dispersion spectrums, stable one-dimensional electrides Ca3Hf2Ge3, Ca3Hf2Sn3, and Sr3Hf2Pb3, were screened out. Interestingly, the superconductivity of these electrides were predicted from electron phonon coupling calculations. It is highlighted that Sr3Hf2Pb3 showed the highest Tc, reaching 4.02 K, while the Tc values of Ca3Hf2Ge3 and Ca3Hf2Sn3 were 1.16 K and 1.04 K, respectively. Moreover, the Tc value of Ca3Hf2Ge3 can be increased to 1.96 K under 20 GPa due to the effect of phonon softening. This work enriches the types of superconducting electrides and has important guiding significance for the research on constructing electrides and related superconducting materials.