Revealing the Mechanisms of Ultrafast Transient Liquid Assisted Growth (TLAG) of REBCO Superconducting Films by In Situ Synchrotron Radiation—X-Ray Diffraction and X-Ray Absorption Spectroscopy

Cuprates, REBa₂Cu₃O_7-δ (REBCO, RE = Y or rare earth) are the most important class of High Temperature Superconducting (HTS) materials, due to their outstanding properties [1-2]. They are the superconductors with the highest operational temperature and highest operational magnetic field, hence, nowadays the materials of choice for Coated Conductor (CC) technology in most of the high current applications. The synthesis of REBCO-type superconducting films is compatible with standard chemical solution deposition methods (CSD) and pulsed laser deposition growth (PLD). However, recently, the development of a novel synthesis approach promises the reduction of the cost/performance ratio in the CC field. The, so called “Transient Liquid Assisted Growth” (TLAG) method [3-5] is a high-throughput, ultra-fast, non-equilibrium, kinetic process of growth of REBCO type superconducting films and coated conductors compatible with industrial applications. The understanding of the TLAG process requires application of advanced tools and techniques for its characterization and optimization. Therefore, development of a specialized instrumentation for the characterization and optimization of TLAG process in real time and in real conditions by synchrotron radiation based in-situ X-Ray Diffraction and X-Ray Absorption at acquisition times down to 100 ms per frame, was achieved. This new instrumentation allows to follow the precursors reaction, the generation of intermediate phases and follow the dynamic growth of the superconducting phase while acquiring the resistance of the sample in real time and in-situ by XRD. Additionally, the liquid phase formation and its oxidation state is characterized by in-situ XANES. Epitaxial REBCO TLAG growth at 1000 nm/s has been reached in superconducting films of 3 MA/cm² at 77 K. Furthermore, TLAG growth method was shown to be compatible with introduction of inorganic nanoparticles as vortex pinning centers to increase the performance of such films. In this presentation, I will mainly report on the present understanding of the TLAG process based on the results gathered from the in-situ instrumentation setup.

References:
[1] T.Puig et al. 2024, Nature Reviews Physics volume, 6, pages132–148
[2] X Obradors et al 2024, Supercond. Sci. Technol, 37 053001
[3] L. Soler et al. 2024, Nat Commun 11, 344
[4] S. Rasi et al. 2022, Adv. Science 2203834
[5] L. Saltarelli 2022, ACS Applied Mater. Interf. 14, 43, 48582