High density, ultrafine precipitates in YBa2Cu3O7−x thin films prepared by plasma-enhanced metalorganic chemical vapor deposition

Abstract

Thin films of yttrium‐rich YBa₂Cu₃O_7−x with c‐axis orientation prepared by plasma‐enhanced metalorganic chemical vapor deposition have been examined by high‐resolution transmission electron microscopy. Yttria precipitates smaller than 50 (Å) in size have been identified in the matrix. They are uniformly distributed, have a high density as large as 10²⁴ per cubic meter and are oriented with respect to the matrix. The magnetic field dependence of the critical current density of the thin films indicates that the yttria precipitates are effective flux pinning centers.