Reactive liquid phase sintering of YBa₂Cu₃O_7-xsuperconducting thin films: Part II. Sintering mechanism and film properties

Reactive liquid phase sintering of the YBCO films prepared from carboxylate solution precursors was investigated. A liquid phase was formed by the BaO—CuO binary compound at 620 °C, which facilitated the crystallization and growth of the YBCO grains. Strong capillary forces associated with the liquid phase sintering resulted in a dense, highly oriented microstructure. The YBCO films processed by this reactive liquid phase process showed T_c(zero)= 90.2 K and J_c= 1.3 × 105 A/cm²at 77 K. The (006) rocking curve measurement indicated excellent grain orientation with a FWHM better than 0.2°. A secondary ion mass spectroscopy (SIMS) study showed uniform film composition, and the film/substrate interaction zone was limited to ≈0.1 μm. Average film roughness was about 32 nm.