The use and implementation of nanocrystals (NCs) are highly dependent on the development of robust strategies capable of delivering high-quality NCs in the form of stable colloids. In particular, oxide perovskites offer numerous chemical structures and physical properties that are highly interesting for material science. This work explores a synthesis route capable of producing different perovskite NCs with sizes of less than 10 nm. These NCs show good colloidal stability in polar solvents with a shelf life longer than 1 year. The synthesis protocol is further studied with nuclear magnetic resonance (NMR) and gas chromatography-mass spectrometry (GC-MS) and optimized by design of experiments (DoE) statistics.

We report a successful fabrication of long-length rolling-assisted biaxially-textured substrate-based coated conductors (CCs) via chemical solution deposition starting from colloidal YBa2Cu3O7-delta (YBCO) solutions containing 5 mol-% preformed BaMO3 (M = Hf, Zr) (BMO) nanocrystals. Partial optimization of the existing continuous reel-to-reel YBCO processing via design of experiments approach allowed us to obtain YBCO nanocomposites that retain 80%-90% self-field performance of the pristine CC and show a 10%-40% improvement of in-field critical current, which is only a moderate performance improvement compared to similar films on single-crystal substrates prepared on lab-scale. Based on x-ray diffraction and transmission electron microscopy studies, we attribute this to worsening of the YBCO texture and strong coarsening of BMO nanoparticles, particularly, BaZrO3, during processing. Possible process improvements to overcome these effects are discussed.

Chemical solution deposition (CSD) of YBa2Cu3O7-delta (YBCO) nanocomposites from colloidal precursor solutions containing double metal oxide preformed nanocrystals is a promising, cost-effective, and reproducible approach to producing superconducting films with high critical current density (J(c)) and enhanced pinning. Here, the influence of the preformed nanocrystal composition on the microstructure and superconducting properties of the YBCO nanocomposite films is studied, with a focus on establishing a simple and scalable process to grow nanocomposites that can be transferred to grow nanoadded coated conductors. Colloidal stable BaZrO3, BaHfO3, BaTiO3, and SrZrO3 nanocrystals (3-6 nm diameter) were synthesized and added to an environmentally friendly low-fluorine YBCO precursor solution. High-quality superconducting layers were grown on LaAlO3 single-crystal substrates from these four nanocomposite precursor solutions in a single deposition process, without the need of a seed layer, yielding self-field Jc of 4-5 MA/cm(2) at 77 K. The different YBCO microstructures produced by the four types of nanocrystals and the resulting microstrain of the films are compared and related with the magnetic-field and angular dependence of Jc. We demonstrate the BaHfO3-containing nanocomposite as the best-performing with a homogeneous distribution of nanoparticles with 7 nm average diameter and a high density of stacking faults, which leads to some of the best superconducting properties ever achieved via low-fluorine CSD. Jc exhibits a much smoother decay in the applied magnetic fields and a much more isotropic behavior for nonparallel magnetic fields, and the pinning force is increased by a factor of 3.5 at 77 K and 1 T with respect to the pristine film.

Achieving high-critical current densities (J(c)) with small artificial pinning centers is a crucial challenge for YBa2Cu3O7- (YBCO) nanocomposite thin films fabricated using chemical solution deposition methods. In this work, the YBCO texture, structure purity, and its J(c) properties were improved by understanding the influence of preformed ZrO2 nanocrystals (Ba2+ consumption) during the nucleation and growth mechanism. This comprehensive study leads to an additional intermediate dwelling step during thermal process to increase the YBCO nuclei density before the YBCO growth, resulting to a self-field J(c) of 5-6MA/cm(2) at 77K for undoped and ZrO2-doped YBCO films. Counter-intuitively, the space and size distribution of the ZrO2 nanocrystals in the YBCO matrix are independent of this intermediate dwelling step.

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.

Highly stable, pure, and anhydrous organometallic YBa2Cu3O7- (YBCO) precursor solutions were prepared by dissolving commercial YBCO powder in acetone by trifluoroacetic anhydride (TFAA) or a mixture of TFAA with propionic acid for low fluorine precursors. It is shown that compared to conventional oil bath heating reported in literature, the reaction to produce YBCO precursor occurs 72 times faster by microwave heating. More importantly, the formation of byproducts is suppressed, as shown by nuclear magnetic resonance (NMR) and mass spectrometry (MS). This approach allows a highly reproducible preparation of superconducting coatings which is of interest for low-cost manufacturing processes capable of large-scale production of the coated conductors via chemical solution deposition (CSD). This technology requires reliable and stable precursor solutions for continuous deposition. In this work, we obtained YBCO thin films on single-crystal substrates ((100)-LaAlO3) with a high critical current density (J(c)) of 3-4 MA/cm(2) in self-field at 77 K using TFA-based YBCO precursors and J(c) of 5-6 MA/cm(2) using low fluorine YBCO precursors.

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.

La presente invention se rapporte au domaine des procedes de production de fils supraconducteurs a haute temperature. La presente invention concerne particulierement un procede de production de fils supraconducteurs a haute temperature consistant a chauffer un film comprenant de l'yttrium ou un metal des terres rares, un metal alcalino-terreux et un metal de transition a une temperature d'au moins 700 °C et a refroidir le film a une temperature inferieure a 300 °C, la chauffe et le refroidissement etant executes au moins deux fois.

Impressive performance has been achieved in (RE)Ba 2 Cu 3 O 7-δ (REBCO) coated conductors, but for many applications, the high cost and ac losses remain prohibitive. Inkjet printing methods combine scalability and low equipment cost with high-resolution patterning, potentially addressing both issues by enabling the production of multifilamentary coated conductors without subtractive processing. The successful production of multifilamentary superconducting YBa 2 Cu 3 O 7-δ (YBCO) structures by inkjet printing of a low-fluorine YBCO precursor solution on SS/ABAD-YSZ/CZO substrates is reported. Two approaches have been developed. In the first method, YBCO filaments were directly deposited on the buffered substrate by piezoelectric printing; and in the second approach, CeO 2 tracks were first printed to pattern a subsequently overprinted YBCO film, creating a multifilamentary structure by an inverse technique. Scanning Hall probe measurements have been used to compare the filamentary structures and critical currents achieved by both methods, and a J c of up to 3 MA cm -2 has been obtained at 77 K. For the inverse printing approach, the ac hysteresis losses have been also measured and compared with theoretical models.

Hybrid solutions of triflouroacetate YBCO precursors and BZO nanoparticles were synthesized and deposited to yield superconducting YBCO–BZO nanocomposite films.

The aim of the joint industrial and academic project "SupraMetall" is to enable the large scale production of superconducting tapes. This is a report of the recent achievements in the production of cube textured metal substrates and the coating techniques of the buffer and superconductive layers. The final coated conductor tapes of 2m length reached critical current densities of 120A/cm-width.

In this paper, we present ink-jet printing as an attractive alternative to lithography and etching methods for the development of multi-filamentary YBa2Cu3O7-δ coated conductors. Our research is mainly focused on the study of the influence of rheological parameters on the printability of water-based inks in order to produce superconducting patterns on SrTiO3 and CeO2-La2Zr2O7-Ni5at%W substrates. An aqueous YBCO precursor ink with a total metal ion concentration of 1.1 mol/L with a viscosity of 6.79 mPa s and a surface tension of 67.9 mN/m is developed. Its printing behavior using several ink-jet printing devices is verified using a camera with strobed illumination to quantify droplet velocity and volume. After optimization of the deposition parameters, YBCO tracks with different dimensions could be printed on both types of substrates. Their shape and dimensions were determined using optical microscopy and non-contact profilometry, showing 100-200 nm thick and 40-200 µm wide tracks. Finally, resistivity measurements were performed on the widest tracks on SrTiO3 showing a clear drop in the resistivity starting from 88.6 K with a ∆Tc of 1.4 K.

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Cheap chemical approaches: CSD/MOD and MOCVD were used and demonstrated to be feasible in 2G-wire production. New reel-to-reel MOCVD pilot system with higher throughput was examined, tuned and used in all YBCO depositions as well as for MgO, LMO, YSZ and CeO2 buffer layers fabrication. YBCO deposition process was found to be stable either at 10 m/h on 50 m long tapes or at 20 m/h on 100 m long tapes. All-layers-by-MOCVD approach allowed to get critical current up to Ic max > 90A/cm-width. On a single CSD-LZO (lanthanum zirconate) buffered Ni-alloy tapes 400nm thick YBCO films with critical current density up to jc max = 1.5 MA/cm2 were obtained. On the basis of single CSD-LZO-buffered tapes, some multiple buffer sandwiches were created and compared in the same YBCO deposition. The best result was reached on CVD-CeO2/1×CSD-LZO/Ni5W buffer oxide system and showed for 650nm thick YBCO rather stable over 2.5 m length Ic = 80-90 A.

The objective of this paper is the development of ink-jet processing as a new technique for chemical solution deposition of YBCO coatings and patterns. Our research is mainly focused on the investigation and determination of the rheological parameters towards the printability of water-based inks in order to produce continuous YBCO coatings or multi-filamentary patterns on SrTiO3 substrates. A 0.185 mol L−1YBCO ink with a viscosity of 4.77 mPa s and a surface tension of 67.9 mN m−1, resulting in a ratio Re/We1/2 of 7.37, is developed. Its printing behaviour is further verified using a camera with strobed illumination to quantify the droplet velocity and volume. After optimization of the deposition parameters, a 350 nm thick YBCO coating showing preferential c-axis orientation could be grown on SrTiO3. This layer exhibits a critical current of 0.67 MA cm−2 at 77 K in self-field. Finally, the shape and dimensions of printed YBCO tracks were determined using optical microscopy and non-contact profilometry, showing 200 nm thick and 200 μm wide tracks.