Improvement of the Superconducting Properties of GdBa2Cu3O7-δ with Nano-Sized Ferrite Addition

We have been investigating the effect of (CoFe2O4)x and (ZnFe2O4)x (x is the wt%) nano-sized ferrites on the superconducting (SC) properties of the high-Tc SC compound GdBa2Cu3O7-δ (Gd123) prepared by the conventional solid-state reaction technique. In this work, the magnetic hysteresis for pure Gd123 samples and samples added with nano-sized ferrites was measured using a superconducting quantum interference device (SQUID) magnetometer using a dc field up to 30,000 Oe. The magnetic Jc was estimated using the extended Bean model. While a clear increase in Jc values with the addition of (CoFe2O4)x nano-sized ferrites is observed, a less clear positive effect on the Jc values is observed with the addition of (ZnFe2O4)x nano-sized ferrites. These results indicate an improvement of grain connectivity, decrease of voids between the grains, and decrease of porosity in Gd123 compound resulting from CoFe2O4 addition consistent with the mechanical properties measured before. (CoFe2O4)x nano-sized ferrite addition has thus resulted in an improvement in the SC properties of Gd123 high-Tc SC compound making it more convenient for applications.