Superconducting YBa₂Cu₃O_7-δ Nanocomposite Films Grown by TLAG-CSD with Embedded BaMO₃ and BaM₂O₆ Nanoparticles

The growth of Chemical Solution Deposition (CSD) nanocomposites from colloidal precursor solutions containing preformed nanoparticles has recently proven to be a very good pathway developing low cost YBa₂Cu₃O_7-δ (YBCO) superconducting layers carrying high currents at high magnetic fields by pinning vortices at none superconducting nanoscale defects [1][2].<br/>Metal oxide nanoparticles such as BaMO₃ (M= Zr and Hf) and BaM₂O₆ (M= Nb and Ta) are the most interesting choices due to their compatibility with YBCO precursor solutions and growth. Using the H2S2 hybrid method, which combines aqueous sol-gel and solvothermal approaches, we have synthesized small-sized, crystalline, monodisperse and stable BaMO₃ NPs. We are able to tune their size in a range of 4 - 20 nm, controlling the hydrolysis step involved in the reaction mechanism [3]. Moreover, small-sized (4-6 nm) and agglomeration-free BaM₂O₆NPs have been obtained, for the first time, using a surfactant-free solvothermal method and a post-synthetic surface functionalization.<br/>We have used the non-equilibrium ultrafast Transient Liquid Assisted Growth (TLAG-CSD) method to grow YBCO nanocomposite films with the above preformed nanoparticles. We have developed a fluorine-free colloidal YBCO precursor solution adapted to TLAG-CSD nanocomposites able to achieve very homogenous and reproducible multideposited films. We have demonstrated the compatibility and stabilization of preformed NPs in the YBCO precursor solution, obtaining homogenous pyrolyzed films with crystalline NPs, homogenously distributed without coarsening. Finally, we have further proved the compatibility and chemical/thermal stability of NPs with the TLAG approach [4], and determined the parameters to achieve epitaxial YBCO multideposited TLAG nanocomposites obtaining the first promising Jc results of 2 MA/cm²at 77 k for 400 nm of thickness.<br/>[1] A. Llordés et al., Nat Mater. 6, 2012, 329-36<br/>[2] Z. Li et al., Scientific Reports 9, 2019, 5828<br/>[3] N. Chamorro et eal., RSC Adv. 10, 2020, 28872-28878<br/>[4] L. Soler et al., Nat Commun. 11, 2020<b>, </b>344