Production of Sharp-Edged and Surface-Damaged Y₂BaCuO₅ by Ultrasound: Significant Improvement of Superconducting Performance of Infiltration Growth-Processed YBa₂Cu₃O_7−δ Bulk Superconductors

Abstract

Growth and physical properties of bulk REBa2Cu3O7−δ (REBCO) superconductors fabricated by the infiltration growth (IG) method strongly depend on the initial size and morphology of the RE2BaCuO5 (211) particles. The present work details the novel method we developed for producing sharp-edged and surface-damaged 211 particles to be added to the REBCO bulks. We employed high-energy ultrasonic irradiation for pretreating the 211 particles and fabricated high-performance bulk single-grain YBa2Cu3O7−δ (YBCO) superconductors via the top-seeded IG process. Increasing the ultrasound irradiation power and time duration mechanically damaged the surface of the 211 particles, producing more fine and sharp edges. Systematic investigations of the microstructural properties of the final YBCO bulks indicated that the size and content of the 211 particles gradually decreased without any additional chemical doping. The effective grain refinement and improved interfacial defect densities enhanced the critical current density by a factor of two at 77 K and self-field as compared to a YBCO sample fabricated without any pretreatment. A maximum trapped field of 0.48 T at 77 K was obtained for a sample (20 mm diameter) with 211 particles treated for 60 min and 300 W ultrasound radiation. The effectiveness of the novel method is demonstrated by the superior performance of the YBCO bulk samples prepared as compared to bulk samples fabricated with the addition of Pt and CeO2. This method is novel, cost effective, and very convenient, maintaining high sample homogeneity, and is free of chemical contaminants as compared to other methods which significantly affect the properties of all REBCO bulk products grown by sintering, melt growth, and IG methods.

Review on the Use of Superconducting Bulks for Magnetic Screening in Electrical Machines for Aircraft Applications

“…This can be seen in Figure 13 where, for a large commercial ring segment-shaped GdBaCuO bulk, a weak area of superconductivity can be seen during a field cooling magnetization at 77 K. Another method for preparing large size single crystal is the so-called infiltrationgrowth technique. This method requires a matrix of precursor materials, a liquid reactive material, and like for the TSMG, a seed on the top of the bulk [60][61][62]. Contrary to the TSMG method, it is easy to control the shape and the density of the precursor matrix and so the characteristics of the prepared superconducting bulk.…”

Investigation of high-energy ultrasonication of RE2BaCuO5(RE = Y, Gd) on the growth and superconducting properties of REBa2Cu3O7−δtop-seeded melt textured bulks

“…The J c and trapped fields of REBCO superconductors directly correlate with the microstructure achieved, therefore, controlling the growth and hence, the microstructure, is crucial to improve the superconducting properties [11][12][13][14][15]. This is due to the fact that J c in the REBCO materials is largely governed by flux pinning at the embedded RE211 particles.…”

“…Hence, it is necessary to look for new and advanced methods of producing nanometer-sized RE211 phase particles within the RE123 matrix without using any chemical dopants. To overcome these problems, Pavan Kumar Naik et al [12,13] have demonstrated a new RE211 particle refinement method employing high energy ultrasonic radiation. This method was applied for the fabrication of YBCO bulk single grains by top-seeded IG process, and improvement of the superconducting properties were achieved.…”

High-energy ultrasonic irradiation effects on the growth and critical current density of top-seeded melt grown single grain YBa2Cu3O7-δ bulk superconductors

“…Among, utilization of smaller sized 211 particles are beneficial for higher growth rates and embedding fine sized non-superconducting particles in Y123 bulk matrix. In this regard, in order to improve the flux pinning of REBCO superconductors, by a team of S. Pavan Kumar Naik et al, for the first time, a novel method of high-energy ultrasonic radiation was employed for pre-treating 211 powders [14][15]. Later this method is applied to other superconductors successfully and improved their performance [16].…”