CALORIMETRIC STUDIES OF SUPERCONDUCTING (LA1-XTHX)NIC2 (X=0.1-0.9)

Heat capacity measurements between approximately 0.4 and 12 K have bee n carried out on (La1-xThx)NiC2 (x = 0.1-0.9) as an extension to an ea rlier study on the superconducting transitions in this Ni-containing s ystem. The transition temperature T-c values corroborate with the prev ious results from electrical and magnetic measurements. The thermodyna mically-based calorimetric data further assure the bulk nature of the observed transitions, even though the highly-reactive-thorium-induced minor phases in the samples cause difficulties in deriving the electro nic heat capacity coefficient gamma. A T-c peak of 7.9 K near x = 0.5 is suggested phenomenologically to be at least partly due to the minim um in inter-planar lattice parameter c of the orthorhombic structure. (C) 1997 Elsevier Science Ltd.