Ni substitution effect on structure and superconductivity properties in Li2(Pd1−xNix)3B boride system

The crystal structure and basic superconductivity parameters in Li2(Pd1−xNix)3B are systematically studied by means of X-ray diffraction method, transport properties and magnetization measurement. The limiting solubility of Ni substitution at Pd site was less than 0.2. The lattice parameter a and superconducting transition temperature Tc decrease gradually with increasing Ni content x. Low critical field Hc1 and upper critical field Hc2 were estimated from the isothermal magnetization (M-H) measurements, and the results showed a decreased tendency with increase in x. From Hc1(0) and Hc2(0), the coherence length ξ(0), penetration depth λ(0), Ginzburg-Landau parameter κ(0) and thermodynamic critical field Hc(0) were estimated and the results are compared with the related systems. The present results supported that Li2(Pd1−xNix)3B system is a conventional type-II superconductor.