Abstract
The formation of superconducting nanocomposites from preformed nanocrystals is still not well understood. Here, we examine the case of ZrO2 nanocrystals in a YBa2Cu3O7−x matrix. First we analyzed the preformed ZrO2 nanocrystals via atomic pair distribution function analysis and found that the nanocrystals have a distorted tetragonal crystal structure. Second, we investigated the influence of various surface ligands attached to the ZrO2 nanocrystals on the distribution of metal ions in the pyrolyzed matrix via secondary ion mass spectroscopy technique. The choice of stabilizing ligand is crucial in order to obtain good superconducting nanocomposite films with vortex pinning. Short, carboxylate based ligands lead to poor superconducting properties due to the inhomogeneity of metal content in the pyrolyzed matrix. Counter-intuitively, a phosphonate ligand with long chains does not disturb the growth of YBa2Cu3O7−x. Even more surprisingly, bisphosphonate polymeric ligands provide good colloidal stability in solution but do not prevent coagulation in the final film, resulting in poor pinning. These results thus shed light on the various stages of the superconducting nanocomposite formation.
Highlights
Generators and other rotating devices used in energy conversion are important applications for the high-temperature YBa2 Cu3 O7−δ (YBCO) superconductor [1,2]
The monocrystallinity and tetragonal structure of the nanocrystals was supported by atomic pair distribution function (PDF)
ZrO2 nanocrystals, synthesized in tri-n-octylphosphine oxide were probed with Pair Distribution Function (PDF) analysis
Summary
Generators and other rotating devices used in energy conversion are important applications for the high-temperature YBa2 Cu3 O7−δ (YBCO) superconductor [1,2]. YBCO nanocomposite films, grown via pulsed laser deposition, were shown to maintain high critical currents in high magnetic fields. In these nanocomposite films, non-superconducting BaMO3 nanocolumns (M = Zr, Hf and Sn) are created in the YBCO matrix by manipulating the film deposition process [4,5]. Nanocolumns generate a good in-field performance when the magnetic field (H) is aligned parallel to them (i.e., H||c-axis) Such defects are correlated pinning centers along the c-axis and produce an enhancement of critical current densities (Jc ) at H||c with a pinning force density of more than 25 GN m−3 at 77 K [5]. Pulsed laser deposition-based coatings already feature an intricate control over the size, shape, and density of pinning centers [4,8,9,10]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
