Superconductivity at about 8 K was observed in the metal-rich Li-Pd-B ternary system. Structural, microstructural, electrical, and magnetic investigations for various compositions proved that the ${\mathrm{L}\mathrm{i}}_2{\mathrm{P}\mathrm{d}}_3\mathrm{B}$ compound, which has an antiperovskite cubic structure composed of distorted ${\mathrm{P}\mathrm{d}}_6\mathrm{B}$ octahedrons, is responsible for the superconductivity. This is the first observation of superconductivity in metal-rich ternary borides containing alkaline metal and Pd as a late transition metal. The compound prepared by arc melting has a high density and is relatively stable in the air. The upper critical fields $H_{c2}(0)$ estimated by linear extrapolation and the Werthamer-Helfand-Hohenberg theory are 6.2 and 4.8 T, respectively.

• Received 6 February 2004

DOI:https://doi.org/10.1103/PhysRevLett.93.247004