Characterization of Er-Added YBCO Coated Conductor Produced by Metal Organic Deposition (MOD)

The effects of adding Er³⁺ to the trifluoroacetate precursor solution used to produce YBa₂Cu₃O_7-times thin films by the MOD method have been investigated. Er-added MOD YBCO films, applied to RABiTS-based substrates, were examined by in-field transport, electron microscopy, and Raman spectroscopy. Er additions up to Er/Y= 1.0 have been studied. Consequences to the, chemistry, microstructure, and electro-magnetic performance of fully processed coated conductor samples were determined. As expected, the added Er increases the relative concentration of atoms that tend to occupy the ldquoYrdquo position in the YBCO lattice, however, Er³⁺ crystal field effects seen in Raman spectra of the Er-added samples indicate that there is little or no Er substitution on the Ba or Cu2 sites. Some Er³⁺appears on Y sites in the YBCO; the remainder is found as nano-sized (Er,Y)₂O₃ precipitates. Current transport measurements as a function of field angle show that J_c increases with H//c but decreases with H//ab as the Er/Y ratio increases towards 0.5. The increased H//c flux pinning is attributed to the Er-rich nano-precipitates; the decreased H//ab flux pinning is attributed to a monotonic reduction in the number of planar defects with increasing Er/Y value.