Superconductivity with Tc up to 14K in CaSi2 under pressure

We have studied the occurrence of superconductivity under pressure in the CaSi2 family of compounds,namely the semimetallic trigonal phase and the a-ThSi2-type tetragonal one. Although only the latter issuperconducting (Tc51.56 K) at ambient pressure, starting from the trigonal phase and applying high pressure~.12 GPa! we have found a new superconducting phase with Tconset;14 K, among the highest ever found insilicon based materials.