Melt-processed YBCO with Pt or Ce additions: comparison of pinning behavior

The critical current density and magnetic relaxation as a function of temperature and magnetic field are compared for the melt-processed YBCO with Ce or Pt additions. The pinning parameters estimated show an enhancement of current density, and consequently pinning force in the presence of Ce. The difference in pinning capabilities between the Ce- and Pt-added melt-processed YBCO samples is attributed to inherent differences in microstructure. It was observed that in the Ce-added sample the size of the 211 particles can be reduced to 200-500 nm, while in the melt-processed sample with Pt additions the size of the 211 precipitates is usually greater. The obtained results suggest that the benefits of melt-processed YBCO with Ce additions come from the increase of the effective pinning area of the refined 211 precipitates.