YBa₂Cu₃O₇ coated conductor grown by hybrid liquid phase epitaxy

The Hybrid Liquid Phase epitaxy (HLPE) approach has the potential to be a high rate-low cost process. This deposition process is used to grow epitaxial YBa₂Cu₃O₇ (YBCO) films in the presence of a thin (100 to 500 nm) liquid BaO-CuO flux layer. Despite the presence of the molten flux, YBCO growth is found to be feasible on technical substrates because of the limited dissolution of the buffer layer in the thin flux layer. The high atom mobility at the growing Interface under the liquid flux enables high growth rates (demonstrated to be greater than 10 nm · s^-1 in a wide temperature regime and predicted to be up to ∼ 50 nm·s ^-1). We report results on HLPE YBCO films grown on (100) strontium titanate and textured technical substrates such as rolling-assisted biaxially textured substrates (RABiTS) and ion-beam-assisted-deposited (IBAD) MgO. High values of the critical temperature above 90 K and critical current ∼400 A per cm width for 3 μm thick films on single crystal substrates and promising high values on technical substrates are obtained. Furthermore, there is potential for making thicker films of the same quality since film density is maintained with thickness. Angular-dependent transport critical current as a function of applied field for these films, as well as microstructural measurements by transmission electron microscopy are also reported. The angular and field dependence of critical current density are similar to standard PLD (pulsed laser deposition) films. Although the films are of high epitaxial quality they contain yttria precipitates which are possible sources of flux pinning centers.