Nano- to microscale structural and compositional heterogeneity of artificial pinning centers in pulsed-laser-deposited YBa2Cu3O7−y thin films

Abstract

The structure, composition, and spatial distribution heterogeneity of artificial pinning centers affect the critical current density of REBa2Cu3O7−y (RE: rare earth) coated conductors. Nanoscale structures and compositions have been analyzed with transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). However, microscale heterogeneity has been difficult to characterize. Here, YBa2Cu3O7−y thin films doped with double-perovskite Ba2YbNbO6 were prepared via pulsed-laser deposition and characterized with TEM, STEM, and scanning electron microscopy (SEM). Cross-sectional and plan-view TEM/STEM imaging revealed hybrid pinning structures consisting of nanorods, nanoparticles, and planar defects that were formed spontaneously. Nanorods were imaged with high spatial resolution via field-emission SEM of thin-foil specimens. Focused-ion-beam (FIB) micro-sectioning enables SEM imaging of microscale heterogeneity in nanorod spatial distributions. By using TEM/STEM in conjunction with FIB-SEM, the coated conductor inhomogeneity was directly evaluated from the nano- to micrometer scales.

Fabrication of YBa2Cu3O7 Superconducting Nanocomposite Film on Silicon Substrate

“…The difference in the Yb concentration between the nanorods and the matrix (Figure e) seems to be smaller than that of Nb (Figure b). The trends of the Yb and Nb distribution is consistent with our previous observations. , The formation of BYbNO nanorods is consistent with the presence of the BYbNO 400 peak in the XRD profile (Figure a). Thus, BYbNO nanorods were successfully formed in the YBCO films on Si.…”

“…The trends of the Yb and Nb distribution is consistent with our previous observations. 24, 37 The formation of BYbNO nanorods is consistent with the presence of the BYbNO 400 peak in the XRD profile (Figure 4a). Thus, BYbNO nanorods were successfully formed in the YBCO films on Si.…”