Progress towards all-chemical superconducting YBa₂Cu₃O₇-coated conductors

Abstract

Chemical solution deposition (CSD) has recently emerged as a very competitive technique for obtaining epitaxial films of high quality with controlled nanostructure. In particular, the all-CSD approach is considered to be one of the most promising approaches for cost-effective production of second-generation superconducting wires. The trifluoroacetate (TFA) route is a very versatile route for achieving epitaxial YBa 2 Cu 3 O 7 (YBCO) layers with high critical currents. In this work, recent advances towards improvement of the performance of several conductor architectures based on the YBCO TFA process will be presented. We show that new improved anhydrous TFA precursors allow a significant shortening of the pyrolysis time (∼1.5 h), and we have increased the total film thickness in a single deposition using polymeric additives. On the other hand, further understanding of the YBCO nucleation and growth process has allowed us to obtain a controlled microstructure and high critical currents (J c ≈ 4-5 MA cm −2 and I c ≈ 300 A cm −1 width at 77 K). The growth conditions (CSD) and post-processing conditions (sputtering and CSD) for the underlying oxide cap and buffer layers (CeO 2 , BaZrO 3 , SrTiO 3 , La 2 Zr 2 O 7 , (La, Sr)MnO 3 ) and of self-organized nanostructures (CeO 2 , BaZrO 3 ) deposited by CSD have been investigated to obtain high-quality interfaces in multilayered systems. Different single-crystal or metallic substrates (YSZ-IBAD (yttrium stabilized zirconia-ion beam assisted deposition) and Ni-RABiT (rolling assisted biaxial texturing)) have been investigated and long (≈10 m) CSD biaxially textured buffers (CeO 2 , La 2 Zr 2 O 7 ) have been grown on Ni-RABiT substrates using a reel-to-reel system. High-performance TFA-YBCO-coated conductors have been obtained on vacuum-based buffer layers (I c ≈ 140 A cm −1 width) and on CSD buffer layers grown on IBAD YSZ-SS (stainless steel) substrates. Finally, we report on recent analysis of the magnetic granularity and vortex pinning properties of TFA-YBCO conductors.

Modified Pechini Synthesis of Oxide Powders and Thin Films

“…Chemical solution deposition has emerged as a highly competitive method for the preparation of YBCO coatings, both in the shape of wires and films, where high quality films can be prepared cost-effectively with high speed without the need for vacuum (Obradors et al 2006).…”

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

“…[9][10][11][12][13] In recent years, significant advances in chemical solution deposition (CSD) of both buffer layer architecture and superconducting layer have shown the potential of CSD-based superconductors for a wide range of technological applications. [14][15][16] Typically, a precursor solution, containing yttrium, barium and copper trifluoroacetates, is successively deposited, pyrolyzed and crystallized into YBa2Cu3O7-δ thin films ( Figure 1). This solution approach offers a less expensive route to the coated conductors design, being more scalable and faster compared to vacuum deposition methods.…”

Solution design for low-fluorine trifluoroacetate route to YBa2Cu3O7films

“…[1][2] The trifluoroacetate approach (TFA-MOD) has been the process mainly used for the preparation of YBCO layers [3] [4]. This barium fluoride process, although currently used for industrial companies in the development of longlength biaxially textured coated conductors is still deeply studied, especially to better understand the underlying decomposition and growth mechanisms and be able to further improve growth rates, thickness, throughputs and performance [5]. This includes, among others, study of the deposition, evaporation, shrinkage and decomposition step, especially for thick layers and correlate them with the use of modified starting solutions [6] [7].…”