Predicted superconductivity in one-dimensional A(3)Hf(2)B(3)-type electrides

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 (T(c)). Therefore, searching for superconducting electrides under low or moderate external pressures is of significant research interest and importance. In this work, a series of A(3)Hf(2)B(3)-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 Ca(3)Hf(2)Ge(3), Ca(3)Hf(2)Sn(3), and Sr(3)Hf(2)Pb(3), were screened out. Interestingly, the superconductivity of these electrides were predicted from electron phonon coupling calculations. It is highlighted that Sr(3)Hf(2)Pb(3) showed the highest T(c), reaching 4.02 K, while the T(c) values of Ca(3)Hf(2)Ge(3) and Ca(3)Hf(2)Sn(3) were 1.16 K and 1.04 K, respectively. Moreover, the T(c) value of Ca(3)Hf(2)Ge(3) 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.