MAGNETIC AND SUPERCONDUCTING PROPERTIES OF ERNI(2-X)M(X)B(2)C (M=CO,PD,PT)

We report lattice parameter and superconducting temperature transition (T-c) measurements on ErNi(2-x)M(x)B(2)C (M=Co, Pd, Pt, x=0.20; M=Co, x=0.05). We discuss the origin of T-c lowering which is relatively mo dest for the substitutions Pd and Pt (dT(c)/dx similar to-12 K) and mo re pronounced for the non-isoelectronic substitution of Co (dT(c)/dx s imilar to-120 K). We also report Er-166 Mossbauer measurements for M=C o, x=0.20 which evidence a main Er3+ ordering temperature near 5 K and a saturated magnetic moment of 8 mu(B).