Substitution and pressure effect on superconducting properties of Na1-xCaxAlSi

This work reports on the substitution of Na+ with Ca2+ in the ternary alkali-metal silicide superconductor NaAlSi. The superconducting transition of NaAlSi takes place at a critical temperature Tc of 7 K. The superconducting properties of CaAlSi were reported to the distortion of the AlSi-layers. The Si bonding network thus plays an important role for the superconducting characteristics. CaAlSi shows a superconducting transition at a Tc of 8.0 K. Na+ and Ca2+ cations have equal ionic radii but Ca provides an additional electron. The observation of the superconducting properties in dependence of electron-doping of Na1-xCaxAlSi is shown. The superconducting properties of Na1-xCaxAlSi were measured using SQUID magnetometry.