Superconductivity at 18 K in Yttrium Sesquicarbide System, Y₂C₃

Abstract

In this study, we investigated superconductivity at 18 K in an yttrium sesquicarbide system, Y 2 C 3 , 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 Y 2 C 3 is a body-centered cubic (Pu 2 C 3 -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 c1 (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 Y 2 C 3 .