Optimization of the TFA-MOD Process for Introduction of ${\rm BaZrO}_{3}$ Pinning Centers in YBCO Films

We present results of a study aimed at understanding the formation of BaZrO₃ (BZO) precipitates in YBCO using the TFA-MOD process, as well as optimizing the BZO concentration with respect to the flux pinning performance. A reference YBCO sample containing no BZO, as well as three samples containing 4, 5 and 6% BZO were made and characterized with respect to in-field critical current (IC) performance and angular field IC dependence. Furthermore, the samples were analysed using transmission electron microscopy to identify the morphology of pinning precipitates and correlate it to the flux pinning behavior. The introduction of BZO does not result in formation of c-axis peaks in the angular field IC behavior, but rather in considerable widening of the ab-plane peaks in the field angular IC behavior with increasing BZO content, as well as in decreased field-angular anisotropy of IC. This behavior is analysed and correlated to the underlying microstructure of pinning precipitates.