Superconductivity at 18 K in yttrium sesquicarbide system, Y2C3

In this study, we investigated superconductivity at 18 K in an yttrium sesquicarbide system. Y2C3, by a magnetization measurement, although this material with a maximum T-c of 11.5 K has already been investigated by Krupka et al. in J. Less-Common Met. 17 (1969) 91. The crystal structure Of Y2C3 is a body-centered cubic (Pu2C3-type) structure, and the lattice parameters are varied by heat treatment conditions. The magnetization (M-H) Curves Of this compound show a typical type-II superconducting behavior, and the lower critical field, H-cl (0), is 3.5 mT. The T-c value in this system is changed in the range from 15 K to 18 K, depending on sintering conditions. The sintering conditions in this work are different from those in a previous work by Krupka et al. We successfully synthesized a new high-T-c phase in Y2C3.