Performance enhancement of Gd–Ba–Cu–O high temperature superconducting bulks by BaHfO3 as pinning centers

Abstract

Since the potential widespread applications of RE–Ba–Cu–O superconducting bulks, it is crucial to enhance their superconducting performances. Binary oxide HfO2 nanoparticles were added into Gd–Ba–Cu–O superconducting matrix before the melt textured growth process. It was found that the HfO2 particles reacted with surrounding matrix and consequently formed BaHfO3 inclusions maintaining nanoscale without significant ripening during the melt growth process. The superconducting transition temperature TC is almost not affected by HfO2 addition, and interestingly, the TC of 0.8mol% HfO2 doped sample increases slightly by about 0.1K in comparison with the undoped one. Meanwhile, the critical current density JC was improved over the whole magnetic field range. These BaHfO3 particles discovered near the liquid phase (Ba–Cu–O, Cu–O, etc.) should be the origin for the improvement of flux trapping capability and critical current density in this system.