Fast synthesis and single crystal growth of Pb-free and Pb-doped Bi-2223 superconductors using alkali chlorides flux technique

Here we report our recent results for the fast synthesis of Bi₂Sr₂Ca₂Cu₃O_10+x phase in powder and single crystal forms using modified alkali chlorides flux technique. For many factors such as flux, crucibles materials, chemical and phase composition of the precursor, temperature and duration of heat treatment, evaporation rate of the flux, their effects on the formation and growth of 2223 have been studied. By optimization of these parameters, the single-phase samples of Pb-doped and Pb-free 2223 phase were obtained in the temperature range of 850-870°C and heat treatment for <15 h, that is much faster, compared with a solid-state reaction technique. The single crystals with the size of 0.5 mm were isolated and characterized using XRD, SEM/EDX, susceptibility and resistivity measurements. The effect of post-annealing in different atmospheres on the oxygen content and superconductivity of the samples was studied by TG and chemical analyses.