High-energy ultrasonic irradiation effects on the growth and critical current density of top-seeded melt grown single grain YBa₂Cu₃O_7-δbulk superconductors

The enhancement of a critical current density (J c) of REBa2Cu3O7-δ (REBCO/YBCO, where RE=rare earth elements and Y) bulk superconductors can be achieved via dispersing normal-conductive RE2BaCuO5 (Y211) particles and other defects which are of nano-metric size in the superconducting matrix. Recently, we demonstrated the integration of high-energy ultrasonic irradiation for fabricating high quality YBCO superconductors which effectively improved J c and trapped fields. In the present work, we investigated the effect of 30 mol.% of Y211 particle produced via high-energy ultrasonication irradiation on the growth and superconducting properties of top-seeded melt grown bulk YBCO single grains. Ultrasonic power of 450 W was employed for 30 minutes to create the sharp-edged, individual and nano-meter sized Y211 phase particles. Systematic isothermal experiments were conducted at various temperatures from 1005 °C-980 °C. The growth of YBCO grain from a single crystalline NdBCO seed was initiated at 1000 °C and as the isothermal temperature decreased the growth area increased due to the improved peritectic reaction. The field dependence of J c was improved when the under-cooling isothermal temperature decreased. The present method is reliable, cost-effective, and free from any chemical contamination.