All-Chemical YBCO-Based Architecture Using a Simplified Multilayer Buffer Deposition

Chemical solution deposition (CSD) is a versatile and cheap technique widely used for both buffer layer and YBa ₂ Cu ₃ O _7−δ (YBCO) epitaxial film growth. One of the main limits hindering the widespread use of the CSD technique in the field of coated conductors is the limited film thickness that can be reached without degradation. Among the different strategies adopted to obtain thicker film by CSD, increase of precursor solution concentration and viscosity can be mentioned. Another interesting approach is the use of multilayer deposition in order to overcome the limits of CSD technique. Multilayer deposition has been so far realized by performing a complete heat treatment - or at least a pyrolysis step - after each deposited layer, resulting in increased processing time and overall cost. In this contribution, we show that an epitaxial multilayer buffer can be easily obtained by means of multiple successive depositions, in which after each layer only a fast drying step of the precursor solution is carried out. In this way, only a single conversion heat treatment can be used. This approach not only allows a significant reduction on the processing time but also it is more suitable for the growth on metallic template. The viability of this approach is shown by using multilayer Zr-doped CeO ₂ buffer deposition on single crystalline YSZ substrate. It is shown that, up to 8 layers, no significant structural and morphological degradation of the buffer layer occurs. Further, YBCO film grown by CSD was used to test the suitability of multilayer buffer. YBCO film grown on multilayer buffer shows excellent superconducting properties, with zero-resistance critical temperature up to 92 K and a critical current density exceeding 1 MA/cm2 at 77 K in self field.