New method of synthesis and physical properties of thick superconducting Er-123 films

We have developed a low-cost, short time manufacturing process using a novel method, starting from a mixture of Er₂BaO₄, BaCuO₂, and CuO, with an excess of Er at expense of Ba. Several micrometers thick films were prepared by the screen-printing technique, spreading the mixture paste on silver substrates, processed then in Ar-1% O₂ atmosphere. Using a double-step annealing process, we obtained good quality Er-123 thick films on silver substrates, with T_c (onset) 92 K. Formation of large flat grains was observed by scanning electron microscope. According to XRD analysis, the films were preferentially c-axis oriented. The magnetic (induced), self-field J_c measured at 77 K was above 32 kA/cm². We observed a strong dependence of the transport current, I_c, on the grain size. The maximum I_c at 77 K as high as 10 A was observed in the sample with the average grain size around 40 μm. The present results indicate that our technology, enabling preparation of large-area superconducting thick films on Ag-based substrates in short processing times, is relatively cheap and appropriate for utilization in long-length RE-123 silver sheath wire production for commercial applications.