On Effect of Ag₂O Addition on Superconducting Performance of YBCO Bulk

Bulk-superconducting samples with Ag doping and without Ag doping were prepared by solid-state reaction method. The authors used X-ray diffraction to analyze texture and phase purity of samples. The results show that the Ag₂O addition is in favor of decreasing sintering temperature and forming c-axis aligned YBCO bulk. SEM and EDAX were respectively used to evaluate the fracture morphology, the distribution of Ag and component of samples. It has been shown that Ag atoms located among YBCO particles help to form SNS knots, which can strengthen intergranular coupling and enhance the critical current density J_c. T_c and J_c were measured using a standard four-probe method by a 1 μv / cm² criterion at 77 K. The results show that Ag doping has no noticeable effect on the T_c of samples, but increases the samples' J_c by one order. In addition, compared with bulk-superconducting samples without Ag doping, the samples with Ag doping are denser, with fewer pores, and are less possible to lose superconductivity in air and laser. Thus, Ag₂O addition in the bulk can strengthen the stability of superconducting samples effectively and make it have a longer life.