Optimizing Nanocomposites through Nanocrystal Surface Chemistry: Superconducting YBa2Cu3O7 Thin Films via Low-Fluorine Metal Organic Deposition and Preformed Metal Oxide Nanocrystals

: Hannes Rijckaert, Glenn Pollefeyt, Max Sieger, Jens Hänisch, Jan Bennewitz, Katrien De Keukeleere, Jonathan De Roo, Ruben Hühne, Michael Bäcker, Petriina Paturi, Hannu Huhtinen, Maximilian Hemgesberg, Isabel Van Driessche

Publisher: AMER CHEMICAL SOC

: 2017

: Chemistry of Materials

: CHEMISTRY OF MATERIALS

: CHEM MATER

: 29

: 14

: 6104

: 6113

: 10

: 0897-4756

: 1520-5002

DOI: https://doi.org/10.1021/acs.chemmater.7b02116

Achieving low cost, safe, reproducible, and high performance superconducting thin films of YBa2Cu3O7-delta is essential to bring this material to the energy market. Here, we report on the chemical solution deposition of YBa2Cu3O7-delta nanocomposites from environmentally benign precursors with a low fluorine content. Preformed ZrO2 nanocrystals (3.5 nm) were stabilized in a methanolic precursor solution via two strategies: charge stabilization and steric stabilization. Counter-intuitively, charge stabilization did not result in high quality superconducting layers, while the steric stabilization resulted in highly reproducible nanocomposite thin films with a self-field J(c) of 4-5 MA cm(-2) (77 K) and a much smaller decay of J(c) with magnetic field compared to YBa2Cu3O7-delta without nanocrystals. In addition, these nanocomposite films show a strong pinning force enhancement and a reduced J(c) anisotropy compared to undoped YBa2Cu3O7-delta films. Given the relationship between the nanocrystal surface chemistry and final nanocomposite performance, we expect these results to be also relevant for other nanocomposite research.