Intergrain connectivity in YBa2Cu3O7-δ superconductor added with Dy2O3 nanoparticles: AC susceptibility investigation

Abstract YBa2Cu3O7-δ (or YBCO) superconductors added with various concentrations of dysprosium oxide nanoparticles (NP-Dy2O3) were prepared using the solid-state process. The additive NP-Dy2O3 has a size of about 10 nm and presents a para/ferromagnetic transition at about 300 K. The characterization of samples was probed via XRD, TEM, SEM, DC magnetization, and AC susceptibility measurements. Some models were employed to compute superconducting parameters like intragranular critical current density under a magnetic field (Jcm(H)), the density of intragranular pinning force for Abrikosov vortex (eg(0)), intergranular critical current density (Jc,inter), intergranular electrical character, superconductor grain volume fraction (fs). The correlation between these parameters and microstructure was discussed. The inclusion of NP-Dy2O3 does not alter the structural properties and the spatial growth of YBa2Cu3O7-δ. NP-Dy2O3 addition led to significant enhancements of Jcm(H) and eg(0). The decrement in Jc,inter was attributed to the change of grain boundary characteristics that transformed from SNS to SINS junction due to NP-Dy2O3 addition.