Superconducting YBa₂Cu₃O_7–δ Nanocomposites Using Preformed ZrO₂ Nanocrystals: Growth Mechanisms and Vortex Pinning Properties

Abstract

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 YBa 2 Cu 3 O 7–δ nanocomposite is fabricated via chemical solution deposition (CSD) using preformed nanocrystals (NCs). Preformed, colloidally stable ZrO 2 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 YBa 2 Cu 3 O 7–δ , unless a thin seed layer is applied. A 10 mol% ZrO 2 NC addition proved to be optimal, yielding a critical current density J C of 5 MA cm −2 at 77 K in self‐field. Importantly, this new approach results in a smaller magnetic field decay of J C (H//c) for the nanocomposite compared to a pristine film. Furthermore, microstructural analysis of the YBa 2 Cu 3 O 7–δ nanocomposite films reveals that different strain generation mechanisms may occur compared to the spontaneous segregation approach. Yet, the generated nanostrain in the YBa 2 Cu 3 O 7–δ 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.