Discovery of Li2(Pd,Pt)3B superconductors

Critical temperature Tc of the Li2(Pd1−xPtx)3B was reported to be 7–8 K for x = 0 and 2.2–2.8 K for x = 1. In this article we present our preliminary results on behavior of magnetization–temperature curves with starting composition of Pd–B precursor, y-Li concentration in LiyPd3B and post-annealing of the Pd-end compound. Results suggest that to maximize Tc ratio Pd:B should be close to 3:1, while y-Li has to be optimum. The lowest Tc for LiyPd3B was 4.4–4.6 K, while post-annealings at 560 °C allowed enhancement of Tc up to 8.2–8.4 K. Compositions Li2Z3B with Z = Ni, Ru, Rh, Re, Ag are not superconducting down to 1.8 K. Exception is composition with Re showing superconductivity due to Re3B compound. All samples were prepared by arc melting.