Effects of heat-treatment conditions on microstructure of Y123 films deposited by TFA-MOD method

Y123 precursor and final films were deposited at various heating rates in the calcination process of metal organic deposition method using trifluoroacetates. The superconducting characteristics were evaluated in the final films. The microstructures and the distributions of chemical compositions of these films were also investigated using transmission electron microscopy and energy dispersive X-ray spectroscopy. In the Y123 precursor film prepared by heating at the rate of 0.2 °C/min in the temperature range from 200 to 250 °C, Cu was distributed uniformly. On the other hand, in the precursor film prepared by heat-treating at the rate of 5 °C/min from 200 to 250 °C, Cu was found to be segregated in the vicinity of the surface of the film. This Cu segregation in the precursor film might cause the differences of crystallinity and superconducting properties of the final film. The former precursor film was grown into a c-axis oriented Y123 film with good crystallinity, and exhibited the high J_C value of 2 × 10 ⁶ A/cm². However, the final film prepared by heat-treating the latter precursor film had many stacking faults of CuO planes, and showed the lower J_C value of 0.3 × 10⁶ A/cm ².