Importance of the pyrolysis for microstructure and superconducting properties of CSD-grown GdBa2Cu3O7\u2212x-HfO2 nanocomposite films by the ex-situ approach

Pablo Cayado,Bernhard Holzapfel,Hannes Rijckaert,Els Bruneel,Jens Hänisch,Isabel Van Driessche,Manuela Erbe

doi:10.1038/s41598-020-75587-4

Pablo Cayado, Bernhard Holzapfel + Show 5 more

Open Access

https://doi.org/10.1038/s41598-020-75587-4

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Abstract

For the first time, GdBa2Cu3O7−x nanocomposites were prepared by chemical solution deposition following the ex-situ approach. In particular, ~ 220 nm GdBa2Cu3O7−x-HfO2 (GdBCO-HfO2) nanocomposite films were fabricated starting from a colloidal solution of 5 mol% HfO2 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. Therefore, the effect of pyrolysis processing parameters such as heating ramp and temperature on the homogeneity of the nanoparticle distribution has been investigated. By increasing the heating ramp to 300 °C/h and decreasing the final temperature to 300 °C, a more homogenous nanoparticle distribution was achieved. This translates into improved superconducting properties of the grown films reaching critical temperatures (Tc) of 94.5 K and self-field critical current densities ({J}_{mathrm{c}}^{mathrm{sf}}) at 77 K of 2.1 MA/cm2 with respect to films pyrolyzed at higher temperatures or lower heating ramps.

Highlights

For the first time, GdBa2Cu3O7−x nanocomposites were prepared by chemical solution deposition following the ex-situ approach
The GdBCO thin films were often fabricated by in-situ techniques, where the expression in situ is related to the crystallization process of the REBCO phase: metal–organic chemical vapour deposition (MOCVD), pulsed laser deposition (PLD) or s puttering[13,14,15,16,17]
This work focused on GdBCO + 5 mol% HfO2 to study the influence of the pyrolysis thermal profile on the final structural and superconducting properties of chemical solution deposition (CSD)-grown nanocomposite thin films

Summary

Introduction

For the first time, GdBa2Cu3O7−x nanocomposites were prepared by chemical solution deposition following the ex-situ approach. Since good and reproducible results had been achieved for the in-situ nanocomposites when the “multistep” pyrolysis profile had been applied in combination with the “standard” profile for the crystallisation (reported and explained in detail in Ref.9), the same thermal treatment was tested for solutions with preformed nanoparticles.

Results

Conclusion