Effects of Li doping on superconducting properties of citrate-gel prepared Y_1–xLi_xBa₂Cu₃O_7–δ Compound

Mahshid Amiri–Moghadam, Hassan Gashmard, Seyed Sajjad Hosseini, Hamideh Shakeripour, Hadi Salamati

The Y_1–xLi_xBa₂Cu₃O_7–δ polycrystalline bulk superconductors doped with Li substituting at the Y site at different concentrations (x = 0, 0.01, 0.02, 0.1) were prepared using the citrate-gel method to study the effects of doping on the superconducting temperature and critical current density. The question was whether Li addition characterized by a high Debye frequency would have any positive effects on T_c. The optimum citrate-gel and heat treatment conditions were identified as those yielding samples with a maximum grain size on the order of 50 μm (up to the optimum Li doping level, x = 0.01). Li substitution at the Y site was verified by structural, electrical, and magnetic measurements of the produced samples, whereas X-ray diffraction (XRD) analysis revealed the formation of a pure phase with no visible impurity phases. Moreover, AC magnetic susceptibility measurements showed no increase in the …