The development of Y Ba₂Cu₃O_x thin films using a fluorine-free sol–gel approach for coated conductors

Abstract

Despite great success in the TFA methods of depositing YBa 2 Cu 3 O x (YBCO) thin films for coated conductors, critical issues involved in removing BaCO 3 have not entirely been settled. There could be other possible ways of dealing with carbon that remains in the film. We have recently developed a fluorine-free sol-gel synthesis with several important advantages including precursor solution stability, improved film density, and elimination of HF during processing. With this approach, high-quality YBCO films have been developed on single crystal substrates with the transport J c s up to 10 6 A cm −2 . In this study, the precursor solution stoichiometry was altered and its effects on superconducting properties were studied. The fluorine-free sol-gel-derived films on the LaAlO 3 (LAO) substrate exhibited epitaxial growth with excellent in-and out-of-plane texture. Experimental details are reported on the sol-gel synthesis chemistry and XRD and TEM characterization of the YBCO thin films. Also discussed is the underlying formation mechanism of the YBCO phase during the synthesis.

Modified Pechini Synthesis of Oxide Powders and Thin Films

“…As a consequence, several modified Pechini routes have been developed as alternatives (Bubendorfer et al 2003), where the formation of barium carbonate can also be avoided (Cui et al 2009). The typical cation precursors are nitrates or acetates, but there is a larger variety in the choice of complexing agents, with CA and EG (Cui et al 2009), EDTA (Brylewski and Przybylski 1993), triethanolamine and acetic acid (Thuy et al 2009) and trimethylacetate and propionic acid (Shi et al 2004) all being applied. Bubendorfer et al investigated several organic acid, such as lactic, tartaric, glycolic, malonic and diglycolic acid, but found that malic acid was the best choice, due to its superior ability to chelate Y 3+ (Bubendorfer et al 2003).…”

Optimization of a fluorine-free metal-organic deposition to fabricate BaZrO3-doped YBa2Cu3O7−δfilm on RABiTS substrates

“…The flat features are the typical c-axis oriented YBCO grains from the MOD process. The terrace surface structure with some outgrowths and a few voids are common characteristics of solution-derived films [10,12]. When the BZO content x ≥ 0.12, the YBCO film displays large holes and a rough surface that may decrease the grain connections and homogeneity of the YBCO phase.…”

“…It is therefore of interest to develop solution processes where HF evolution is eliminated or greatly reduced. There are some low-fluorine [7,8] and fluorine-free (F-free) precursors [9][10][11][12][13][14] that have been prepared for this purpose. One of these F-free processes is an acetylacetonate (AcAc) solution-based MOD technique, originally developed by the National Institute of Advanced Industrial Science and Technology (AIST) [15][16][17] and used by Sumitomo Electric Industries [18].…”

A Fluorine-Free Oxalate Route for the Chemical Solution Deposition of YBa2Cu3O7 Films

“…In the hydroxides route Ba(OH) 2 and Y-and Ba-trimethylacetates are reacted in propionic acid with amine solvent. Remarkably, it has been reported that this stock solution is stable in air and has a shelf life longer than 2 years [34][35][36]. On the other hand, the CSD based on nitrates, which is also known as polymer-assisted deposition (PAD) because of the use of polymers, obtains a homogeneous distribution of the metal precursors in the solution and the formation of uniform metal-organic films [37].…”