Morphology and orientation of ultrafine Y2O3 precipitates in YBa2Cu3O7-x thin films

Abstract

Yttrium-rich YBa2Cu3O7-x (YBCO) thin films grown by plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD), have been reported to have high critical current densities (Jc) of > l×106A/cm2 at 77K. Electron microscopy has been used to understand how excess Y is incorporated into thin film microstructures without affecting their superconducting properties. In this work, we report identification of small Y2O3 precipitates, their morphologies and orientation relationships in YBCO thin films.Details of thin film growth process have been reported elsewhere. The films were examined both in planar and in cross-sectional view by electron microscopy. TEM samples were prepared by conventional mechanical polishing and ion milling techniques. An ISI-002B high resolution electron microscope with a resolution limit of ∼0.18 nm at 200keV was used for observations.