In this work, we tried to improve the superconducting performance of bulk YBa2Cu3Oy (Y123) superconductors via Y2Ba1Cu1O5 (Y211) secondary phase refinement. A novel method of ultra-sonication was used to refine… Click to show full abstract
In this work, we tried to improve the superconducting performance of bulk YBa2Cu3Oy (Y123) superconductors via Y2Ba1Cu1O5 (Y211) secondary phase refinement. A novel method of ultra-sonication was used to refine the Y211 secondary phase particles. The Y211 powder was treated by ultra-sonication for 0 to 80 min with steps of 20 min, keeping the power (300 W) and frequency (20 kHz) constant. For synthesis of the YBCO bulk, we employed top-seeded melt growth (TSMG) with Pt addition. Magnetization measurements showed a superconducting transition temperature at around 91 K, irrespective of ultra-sonication parameters. Interestingly, critical current density and trapped field were found to be proportional to the ultra-sonication duration. YBCO bulk sample (20 mm diameter, 7 mm in thickness) fabricated for 80 min ultra-sonicated Y211 showed a maximum trapped field of 0.42 T at 77 K, 0.3 mm above the top surface. The improved trapped field values are explained on the basis of improvements in the microstructure.
               
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