Physical properties of a novel rare-earth boron carbide compound Sc3B0.75C3

Physical properties of the recently discovered Sc-based boron carbide compound Sc3B0.75C3 were investigated. Sc3B0.75C3 has a tetragonal crystal structure (a=0.333150(3) nm, c=0.76737(1) nm, P4/mmm (No.123)) and has a basic structure composed of chains of [Sc10] polyhedra parallel to the c-axis and containing linear C-B-C chains. The temperature dependence of the resistivity exhibited a change around 60 K. As temperature was lowered from 300 K, a metallic dependence was observed, but an upturn of the resistivity occurred below 60 K. A striking feature was observed in that a sharp jump in the magnetic susceptibility was observed at 63 K. The occurrence of a metal to insulator transition is a viable possibility. In this case the origin of the transition is attributed to the presence of site disorder in the C-B-C chain-end sites.