Identification of epitaxial Y₂O₃ inclusions in sputtered YBa₂Cu₃O₇ films: Impact on film growth

Y₂O₃ inclusions with typical sizes between 100 and 300 nm³, densely distributed (10¹⁶ cm⁻³) in sputtered YBa₂Cu₃O₇ (YBCO) films on SrTiO₃ substrates, have been identified by high‐resolution electron microscopy. The precipitates exhibit either cuboid or needlelike shapes and grow epitaxially within and on top of YBCO. The dominant orientation relationship corresponds to a situation where the two‐dimensional lattices are nearly coincident in the interfacial (001) plane. These precipitates may contribute to the generation of screw and edge dislocations. In addition, they provide a large number of potential pinning sites for magnetic flux lines, which may contribute to the observed high critical current densities.