Enhanced in-field critical currents of YBCO second-generation (2G) wire by Dy additions

The addition of dysprosium oxide nanoparticles is shown to improve the critical current in perpendicular magnetic fields for second-generation (2G) wire formed by metal–organic deposition (MOD). Typical enhancements in Jc are from 0.17 MA cm−2 to over 0.33 MA cm−2 at 77 K and Bperp = 1.5 T. TEM analysis shows that we are introducing (Y,Dy)2O3 nanoparticles with dimensions of 10–50 nm. A simple theoretical analysis shows that the maximum pinning effect for additions is expected at excess concentrations of approximately 70% DyO1.5, i.e. for YBa2Cu3O7−δ+0.7DyO1.5 if the added nanoparticles are randomly dispersed and a strong pinning model is valid. An interesting feature is that the critical current in parallel field is reduced in these samples. We present evidence that shows this may be due to reduced planar defects in the YBCO.