Solving the problem of scalable production methods for low-cost, efficient and flexible high temperature superconducting materials (HTS) compatible with Coated Conductors (CC) technology is one of the goals set for the Energy Transition. Nowadays, HTS based on REBa₂Cu₃O₇ (RE=Y or Rare Earth, REBCO) are manufactured as long, flexible conductors deposited on metallic substrates using thin film technologies, which are rather expensive. An alternative and highly innovative method, called Transient Liquid Assisted Growth (TLAG) [1] is used in our approach. It is a non-equilibrium process based on epitaxial crystallization from a transient melt at very high growth rates (100 nm/s, 100 times larger than conventional methods). This process is compatible with low cost, scalable chemical solution deposition methods and allows to grow high temperature epitaxial superconducting films. However, in order to better understand and control the process, determine the phases´ evolution and the kinetic phase diagrams that would permit to better control the properties of as grown REBCO thin films, a new methodology had to be developed. This goal is being achieved through fast acquisition of in-situ X-Ray diffraction data during the TLAG process at the NCD-SWEET synchrotron beamline of ALBA synchrotron in Spain. For that purpose, a unique portable system was developed using a fast heating XRD furnace capable to rise the temperature up to 1000 °C at rates up to 300 °C/min and controlled atmosphere with total pressures from 10^-5 bar to 1 bar while controlling the oxygen partial pressure and flow rate, all synchronized with simultaneous acquisition of 2D XRD images at 100 ms/image at 18 keV. Additionally, the system allows for simultaneous analysis of the volatiles with mass spectrometry and in-situ electrical conductivity that permits to follow the phase transformation from the insulating precursor phases to the metallic superconductor phase at the growth conditions. The ultrafast process of TLAG required very fast time responses of all the systems and accurate time synchronizations. Results on the epitaxial nucleation and growth mechanism of the REBCO phase on STO single crystals and metallic substrates, and TLAG phase evolutions process will be discussed.

[1] L. Soler et al, Nature Communications, 11, 344 (2020) * Research funded by ERC-2014-ADG-669504 and CSIC PTI-TRANSENER+