Effects of Al2O3 nanoparticles on YBCO superconductor prepared using pyrophoric reaction

The objective of this work is to investigate the effect of Al₂O₃ nanoparticles on structural and superconducting properties of YBa₂Cu₃O_7-x (YBCO) produced using pyrophoric reaction. A series of YBCO samples with small amounts (0 - 1.0 wt %) of nanosized Al₂O₃ (- 10 nm) were characterized with XRD, and SEM measurements. Critical current J_c and critical temperature T_c measurements were performed using a standard four-probe technique at liquid nitrogen temperature. SEM analysis have shown that Al₂O₃ nanoparticles was distributed along the grain boundaries which at higher wt % will reacts with the YBCO matrix to form Al rich spots intergrown within the YBCO superconducting matrix which then confirmed by XRD analysis. The incorporation of Al into YBCO structure slightly reduces the T_c. In spite of the decrease of the superconducting temperature T_c with increasing Al₂O₃ nanoparticles addition, the J_c behavior is remarkably improved. The characteristic behavior of J_c can be explained in terms of the grains connectivity and recrystalization improvement.