Superconductivity in La(Ni$_{1-x}$T$_{x})$C$_{2}$ (T = Cu, Ti, and Pt)

LaNiC$_{2}$, which crystallizes in an orthorhombic CeNiC$_{2}$ type structure with space group A$_{mm2}$, is the first nickel-based ternary carbide superconductor with T$_{c} \quad \sim $ 2.7 K.$^{1,2}$ Previous report showed that about 50{\%} substitution of La in LaNiC$_{2}$ with the 5f thorium (Th) element could enhance the superconducting critical temperature T$_{c}$ up to 7.9 K.$^{3}$ We present the results of static magnetization and electric resistivity data for fifteen polycrystalline La(Ni$_{1-x}$T$_{x})$C$_{2}$ (T = Cu, Ti and Pt) compounds measured in the temperature range 1.8 $\sim $ 4.4 K and 2.0 $\sim $ 300 K, respectively. Discussion of the improvement, with respect to pure LaNiC$_{2}$, on the superconducting critical temperature T$_{c}$ will be directed toward the changes of valence, lattice parameters as well as the effects of solubility limit in the pseudoternary La(Ni$_{1-x}$T$_{x})$C$_{2}$ alloys. $^{1}$W.H. Lee, H.K. Zeng, Y.D. Yao and Y.Y. Chen, Physica C \textbf{266}, 138 (1996). $^{2}$V.K. Pecharsky, K.A. Gschneidner, Jr., and L.L. Miller, Phys. Rev. B \textbf{58}, 497 (1998). $^{3}$W.H. Lee and H.K. Zeng, Solid State Commun. \textbf{102}, 433 (1997).