Effects of Fullerene Addition on Pinning Properties and Microstructures in Melt-Textured Y-Ba-Cu-O Superconductors

Abstract

Bulk Y-Ba-Cu-O superconductors have significant potential for engineering applications due to high critical current density ( J c) and high trapped magnetic fields, which is attributed to the presence of pinning centers such as micro-sized Y2BaCuO5 (Y211) inclusions. The introduction of nanosized particles is known to function as more effective pinning centers than micro-sized ones. It has been reported that J c values were enhanced with the addition of nanosized particles such as ZrO2 and Y2Ba4CuMOy (M = Nb, Zr, etc.) in the YBa2Cu3O x (Y123) matrix. We have focused on nanocarbon as another candidate of the pinning center and reported that the addition of carbon nanotube (CNT) and nanodiamond led to the enhancement of J c in Y-Ba-Cu-O superconductors. Fullerene (C60) is also expected to improve the flux pinning performance. We then fabricated melt-processed Y-Ba-Cu-O bulk samples with the addition of fullerene and investigated the pinning properties and microstructures. SEM observation showed that nanosized particles were distributed in the Y123 matrix. J c exhibited the highest values for the sample with 1.0 wt% fullerene addition. These results suggest that fullerenes act as effective pinning centers.