THERMAL-EXPANSION OF THE HEAVY-FERMION SUPERCONDUCTOR UNI2AL3

We have investigated the superconducting and the antiferromagnetic tra nsition of polycrystalline UNi2Al3 by means of high-resolution dilatom etry. At T(c) = 0.95 K and T(N) = 4.6 K the thermal-expansion coeffici ent alpha shows second-order phase-transition anomalies of negative si gn. Investigations of the antiferromagnetic transition under magnetic fields indicate a complex magnetic phase diagram reminiscent of that o f the Pd homolog.