Optimization of BaZrO₃ concentration as secondary phase in superconducting YBa₂Cu₃O₇ for high current applications

We report the superconducting state properties of YBa₂Cu₃O₇ (YBCO) on introduction of BaZrO₃ (BZO) as a secondary phase. YBCO+xBZO (x= 0, 2, 4, 6, and 10 wt%) composite samples were prepared by solid state reaction method and characterized for structural, morphological and superconducting properties. X-ray diffraction confirms the increased crystallinity and images of scanning electron microscopy measurement show an increase in both grain size and grain connectivity on addition of BZO in YBCO. These effects are well pronounced in an applied magnetic field. Critical current density, J_C, as well as the pinning force peaks at 4% of BZO concentration showed significant difference. A three-fold enhancement in J_C and a six-fold enhancement in pinning force were observed at this optimum BZO concentration. This has been attributed to the pinning of flux lines in YBCO due to introduction of BZO as a secondary phase. These results show that this composite has potential application in high current applications.