SUPERCONDUCTIVITY IN THE Y-PD-B-C SYSTEM

The discovery of superconductivity at 12 K in the single-phase YNi2B2C compound and at 23 K in the multiphase YPd5B3C0.2 compound has renewed the interest in the field of intermetallic superconductors. We have made an extensive study of superconductivity in Y-T-B-C (T = Pd, Ru and Pt) systems, starting with nine different compositions of Y, Pd, B, C and using transport and low-field magnetization measurements. We observed an onset of superconductivity al 23 K and zero resistance at 20 K in the multiphase YPd3B2Cy (y < 0.1) compound. Magnetization measurements also show an onset of diamagnetic signal at 23 K. The compound YPd4B4Cy (y < 0.1) exhibits a drop in the resistivity at 23 K. However, no zero resistance was observed for this compound. As cast the compound YPd3B2 (melted without C) does not show any sign of superconductivity down to 4.2 K. A detailed comparison of the X-rav diffraction pattern of superconducting and nonsuperconducting samples has been given No superconductivity was observed in the other compositions studied in the present work and neither in YRu3B2Cy (Y < 0.1) nor in YPt3B2Cy (Y < 0.1) systems.