Impact of deoxygenation/reoxygenation processes on the superconducting properties of commercial coated conductors.

We report the evolution of the superconducting properties of a commercial coated conductor during deoxygenation and reoxygenation processes. By analyzing the changes on the critical temperature, T, and critical current density, J, at 4 and 77 K, we have identified the conditions that cause a complete deoxygenation of the coated conductor and, also, the reoxygenation conditions that allow a recovery of the superconducting properties. A complete suppression of superconductivity happens at ~ 500-550 °C under a pure argon flow.

Critical current density improvement in CSD-grown high-entropy REBaCuO films.

High-entropy oxide (HEO) superconductors have been developed since very recently. Different superconductors can be produced in the form of a high-entropy compound, including REBaCuO (REBCO). However, until now, mainly bulk samples (mostly in polycrystalline form) have been reported.

Unravelling the Crystallization Process in Solution-Derived YBaCuO Nanocomposite Films with Preformed ZrO Nanocrystals via Definitive Screening Design.

A low-cost chemical solution deposition technique was employed to prepare YBaCuO (YBCO) nanocomposite films starting from a colloidal solution containing preformed ZrO nanocrystals. As previous publications revealed, an increase in the amount of nanocrystals results in a progressive deterioration of the film properties. The parameters that control this process and their interplay are still unknown in detail.

BCO mixtures with large difference in rare-earth ion size: superconducting properties of chemical solution deposition-grown Yb Sm BaCuO films.

The main objective of this work was to study the superconducting properties of BCO films with a mixture of rare-earth () ions with large difference in ion size, in particular Sm and Yb. These Yb Sm BaCuO films have been successfully prepared for the first time by chemical solution deposition following the extremely low-fluorine route, which allows reducing the fluorine content by 93% with respect to standard full trifluoroacetate solutions. On the one hand, critical temperature remains stable at approximately 90 K with Sm content up to = 0.

Importance of the pyrolysis for microstructure and superconducting properties of CSD-grown GdBaCuO-HfO nanocomposite films by the ex-situ approach.

For the first time, GdBaCuO nanocomposites were prepared by chemical solution deposition following the ex-situ approach. In particular, ~ 220 nm GdBaCuO-HfO (GdBCO-HfO) nanocomposite films were fabricated starting from a colloidal solution of 5 mol% HfO nanoparticles. Hereby, one of the main challenges is to avoid the accumulation of the nanoparticles at the substrate interface during the pyrolysis, which would later prevent the epitaxial nucleation of the GdBCO grains.

CSD-Grown YGdBaCuO-BaHfO Nanocomposite Films on Ni5W and IBAD Technical Substrates.

Chemical solution deposition (CSD) was used to grow YGdBaCuO-BaHfO (YGBCO-BHO) nanocomposite films containing 12 mol% BHO nanoparticles and various amounts of Gd, , on two kinds of buffered metallic tapes: Ni5W and IBAD. The influence of the rare-earth stoichiometry on structure, morphology and superconducting properties of these films was studied. The growth process was carefully studied in order to find the most appropriate growth conditions for each composition and substrate.

Chemical solution deposition of Y Gd BaCuO -BaHfO nanocomposite films: combined influence of nanoparticles and rare-earth mixing on growth conditions and transport properties.

Y Gd BaCuO -BaHfO (YGBCO-BHO) nanocomposite films containing 12 mol% BHO nanoparticles and different amounts of Gd were prepared by chemical solution deposition following the trifluoroacetic route on SrTiO single crystals in order to study the influence of the rare earth stoichiometry on structure, morphology and superconducting properties of these films. We optimized the growth process for each of several Gd contents of the 220 nm thick YGBCO-BHO films by varying crystallization temperature and oxygen partial pressure. This optimization process led to the conclusion that mixing the rare earths in YGBCO-BHO films leads to wider growth parameter windows compared to YBCO-BHO and GdBCO-BHO films giving larger freedom for selecting the most convenient processing parameters in order to adapt to different substrates or applications which is very important for the industrial production of coated conductors.