Superconducting YBa_sub2sub_Cu_sub3sub_O_sub7–δsub_ Nanocomposites Using Preformed ZrO_sub2sub_ Nanocrystals: Growth Mechanisms and Vortex Pinning Properties
Katrien De Keukeleere, Pablo Cayado, Alexander Meledin, Ferran Vallès, Jonathan De Roo, Hannes Rijckaert, Glenn Pollefeyt, Els Bruneel, Anna Palau, Mariona Coll, Susagna Ricart, Gustaaf Van Tendeloo, Teresa Puig, Xavier Obradors, Isabel Van Driessche. Advanced Electronic Materials. DOI: 10.1002/aelm.201600161
Although high temperature superconductors are promising for power applications, the production of low-cost coated conductors with high current densities—at high magnetic fields—remains challenging. A superior superconducting YBaCuO nanocomposite is fabricated via chemical solution deposition (CSD) using preformed nanocrystals (NCs). Preformed, colloidally stable ZrO NCs are added to the trifluoroacetic acid based precursor solution and the NCs' stability is confirmed up to 50 mol% for at least 2.5 months. These NCs tend to disrupt the epitaxial growth of YBaCuO, unless a thin seed layer is applied. A 10 mol% ZrO NC addition proved to be optimal, yielding a critical current density J of 5 MA cm at 77 K in self-field. Importantly, this new approach results in a smaller magnetic field decay of J(H//c) for the nanocomposite compared to a pristine film. Furthermore, microstructural analysis of the YBaCuO nanocomposite films reveals that different strain generation mechanisms may occur compared to the spontaneous segregation approach. Yet, the generated nanostrain in the YBaCuO nanocomposite results in an improvement of the superconducting properties similar to the spontaneous segregation approach. This new approach, using preformed NCs in CSD coatings, can be of great potential for high magnetic field applications.