Enhanced flux pinning and critical current density in YBa₂Cu₃O_7-d through dual nanoparticle doping: A comparative investigation of PbO/semiconductor oxide and Ag/semiconductor oxide

The distinctive feature of this work lies in the role of co-adding different types of nanoparticles (NPs) systems to enhance magnetic flux pinning (MFP) and critical physical parameters (CPP). Two different types of NPs inclusion in YBa₂Cu₃O_7-d (Y123) material are considered, namely metal-semiconductor (M-SC) or semiconductor-semiconductor (SC-SC). The primary metal and semiconductor additives selected are Ag and PbO, while TiO₂ and WO₃ serve as secondary SC additives. Phase purity was confirmed through powder X-ray diffraction (PXRD) and scanning electron microscopy (SEM) analysis. Electrical conductivity analysis near the beginning of the superconducting transition (ST) was used to calculate key CPP at temperature 0K, such as the critical current density J_co, the lower and the upper critical magnetic fields, B_co1 and B_co2, respectively, and the flux creep activation energy (U_a) was extracted from electrical resistivity close to the end of ST. Despite the presence of Ag along with SC that advances the transition to the superconducting state, mixing PbO and WO₃ in the Y123 proved to work better for vortex pinning traits, and strengthening the CPP and characteristics of the grain coupling barriers.