Doping effect of Ag nanoparticles on critical current of YBa2Cu3O7−δ bulk superconductor

► YBa2Cu3O7-δ samples were doped by 1 and 2 wt.% of Ag nanoparticles with different sizes. ► It was observed that the Jc increased monotonically by increasing of Ag particle sizes up to 700 nm. ► Jc was greater for samples with higher Ag concentration. ► The enhancement of Jc is attributed to the better crystallization and connectivity of the grains.