Effect of ZnO/TiO2 Nanorods Fabricated Using the Electrospinning Method in Y-Ba-Cu-O Single Grain Bulk Superconductors

In this study, the enhanced superconducting properties of single grain bulk Y-Ba-Cu-O (YBCO) superconductors by the addition of ZnO and TiO₂ nano-rods (NRs) were investigated. The NRs were prepared using the electrospinning method, in which size is twice the coherence length of the superconductor and is intended supposed to serve as columnar defects to provide efficient pinning. The experimental results showed that there were no weak links formed by the addition of the NRs. All of the bulks exhibited a single grain structure, and the distribution profiles of the trapped fields were symmetrical. The value of the maximum trapped field (Bt, max) was enhanced to 0.12 T, which was 1.5 times higher than the undoped sample (approximately 0.08 T). In addition, J_c was also enhanced by the addition of the NRs. The self-field at 77 K was 4.6×10⁴Acm^-2 of the 0.05wt% ZnO NRs-doped and 0.1wt% TiO₂ NRs-doped samples, respectively, which was higher than that of the undoped sample of 2.5×10⁴ Acm^-2. A microstructural analysis demonstrated that there was no reaction occurred between the NRs and YBCO precursors during the melting process. The size and shape of the NRs found in the matrix of the grown bulk were the same as those of the precursors. Consequently, the enhanced superconductivities were then attributed to the increased interface areas between the NRs and the matrix.