Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process

Abstract

The ex situ process has emerged as a popular technology for growing epitaxial YBa 2 Cu 3 O 7 (YBCO) for the second generation of coated conductors. The process combines low cost, ease of scale-up, the possibility of achieving high critical currents in relatively thick YBCO layers, as well as high tolerances to substrate misalignment. All of these factors explain why the process is increasingly becoming adapted by manufacturing companies for the production of YBCO wires. Studies of the barium fluoride variant of the ex situ process have offered rare insights into the structure, chemistry and pinning in ultra-thick, 5 µm, ex situ YBCO layers. The transition to thick YBCO layers is viewed as one of the key ingredients of the commercial success of the YBCO wire technology, which makes these studies especially relevant. This review is intended to be a comprehensive introduction into the history, physics and chemistry of barium fluoride processing, discussed concomitantly with recent results and trends in this field. Furthermore, comparisons are made between YBCO films made by ex situ and in situ deposition processes.

A route for a strong increase of critical current in nanostrained iron-based superconductors

“…5b. The similar behaviour, that is, the absence of a power-law decay (or almost no change in α ), has been found in both cuprate and iron-based superconducting films with strong vortex pinning67860. It appears the irradiated FST films also exhibit an extremely good J c retention at low field, indicating the potential of the iron-based superconductors for utility cable application.…”

Highly efficient solid state catalysis by reconstructed (001) Ceria surface

“…Fluorinated precursor layers were deposited on the substrate by spin-coating, which yielded 0.8 μm thick YBCO film. The films were processed at 800°C in an atmosphere comprised of 300 mTorr oxygen and 300 mTorr water vapor in order to convert the precursor into an epitaxial YBCO layer44. The YBCO nucleation density was inferred from the optical and the Raman microscopy (Vitec Raman microscope) maps of mechanically polished film samples45.…”

Epitaxy of buffer layer and superconducting performance development of YBCO on bi-layer buffers coated on Ni5W by all CSD

“…The epitaxial growth of YBCO film depends on several parameters, such as temperate, oxygen partial pressure, lattice misfit with the substrate, etc. In addition, both the degree the biaxial texture or the surface roughness are key parameters to optimize the critical currents in YBCO films grown by CSD [25][26][27][28]. In fact, the cap layer adjacent to superconducting layer is the genuine substrate for the growth of superconducting layer.…”