High temperature superconductors (HTS) are one of the most ambitious achievements since the discovery of superconductivity and they have the potential to revolutionize large-scale applications in the form of coated conductors (CC). REBa₂Cu₃O_7–d(REBCO, RE = Rare Earth) coated conductors which belong to the class of HTS called cuprates are one of the highly studied materials due to their exceptional superconducting properties. Although there are many material science and engineering challenges set forth in the fabrication of high performance CC. The novel growth method developed at ICMAB for the fabrication of REBCO films is an ultrafast (100-1000 nm/s) and cost effective technique which combines Chemical Solution Deposition (CSD) with a non-equilibrium Transient Liquid Assisted Growth (TLAG) method [1,2].

The superconducting properties of REBCO coated conductors are highly determined by its oxygen doping state. Therefore, oxygen incorporation into the REBCO lattice is an important step in the fabrication process. Optimally doped films have maximum T_c, but maximum critical current density, J_c can be achieved if one goes to the overdoped state where J_c increases as a consequence of an increase in condensation energy. This was demonstrated in TFA-CSD and PLD grown YBCO films oxygenated at lower temperatures [3]. It is expected that oxygenations at low temperatures will favour reaching the overdoped state, however then we need to cope with the low oxygen diffusion.

In this work, we want to overcome this challenge by using ozone assisted oxygenation in TLAG-YBCO films and study their superconducting properties and doping state. Optimization of ozone treatment based on the parameters ozone concentration, temperature, and dwell time will be presented. We demonstrate that the ozone assisted oxygenation has much faster kinetics compared to plane oxygen. The microstructural analysis from TEM measurements to understand the deleterious effect of high ozone concentrations is also included. Finally, we demonstrate the effect of ozone treatments in TLAG-YBCO nanocomposites.

[1] Soler, L., Jareño, J., Banchewski, J. et al. Ultrafast transient liquid assisted growth of high current density superconducting films. Nat Commun 11, 344 (2020)
[2] Rasi, Silvia, et al. “Kinetic Control of Ultrafast Transient Liquid Assisted Growth of Solution‐Derived YBa₂Cu₃O_{7 ‐x} Superconducting Films.” Advanced Science, 2022, p. 2203834.
[3] Stangl, A., Palau, A., Deutscher, G. et al. Ultra-high critical current densities of superconducting YBa₂Cu₃O_7-δ thin films in the overdoped state. Sci Rep 11, 8176 (2021).