The enhancement of superconducting transition temperature in yttrium sesquicarbide system, Y2C3, with the maximum Tc of Tc=18K

We discovered the enhancement of superconducting transition temperature, Tc, in yttrium sesquicarbide system with the maximum Tc of Tc=18K and their superconducting properties were discussed. The crystal structure of Y2C3 is the body-centered cubic (Pu2C3-type) structure, and the lattice parameters are varied with the heat treatment conditions. The magnetization (M-H) curves of this compound showed a typical type-II superconducting behavior, and the lower critical field, Hc1(0), is 3.5mT. The Tc-value in this system was changed in the range from 15K to 18K, depending on the sintering conditions. In a previous report by Krupka et al., maximum Tc in Y2C3 was observed at 11.5K by the magnetic measurements. So we successfully synthesized the new high-Tc phase in Y2C3.