Influence of Substrate-Film Reactions on YBCO Grown by Fluorine-Free MOD Route

Abstract

Recently, fluorine-free metal organic deposition routes (FF-MOD) for growth of YBCO superconducting films have attracted increased attentions. In this work, a comparison study was performed on the YBCO-Ag superconducting thin films deposited on two types substrates, LaAlO 3 and CSD-Ce 0.9 La 0.1 O 2-y (CLO)/YSZ respectively. Although conventional TFA-MOD derived YBCO films exhibit high performance on both substrates, the results vary when using the FF-MOD precursor. SEM and XRD results reveal that c-axis and a/b axis orientations co-exist in the YBCO-Ag films grown on the CSD-CLO/YSZ substrate deposited by the FF-MOD route, while the BaCeO 3 by-product is a dominating phase in the fully reacted film. Based on the structural analysis of the partially converted films, we found that interfacial reactions between the film and the CLO cap layer play an essential role on the epitaxial growth of YBCO-Ag films from the FF-MOD solution. Because of the different chemical reaction path compared to conventional TFA-MOD routes, it seems that the polycrystalline BaCeO 3 formation takes place prior to the YBCO-Ag epitaxial growth associated with the melting process, which results in structural deterioration at high growth temperatures and therefore no superconductivity. This study indicates the necessity of further reducing the nucleation temperature of YBCO films processed by FF-MOD routes.

Insight into the Interfacial Nucleation and Competitive Growth of YBa2Cu3O7−δ Films as High-Performance Coated Conductors by a Fluorine-Free Metal–Organic Decomposition Route

“…First, log–log scale J c ( B ) dependence (H//c at 77 K) in the YBCO film is plotted, as shown in Figure . Remarkably, a high J c value of 3.6 MA/cm 2 was achieved on the CeO 2 -buffered technical substrate at 77 K self-field, which is quite comparable with that grown on the LaAlO 3 single crystal . It is known that accommodation field ( B *), defined as J c ( B *) = 0.9* J c (0), is normally associated with a single-pinning regime in the low field, while the parameter α in J c ∝ B –α corresponds to a collective interaction regime of vortices in the medium fields range.…”

“…Remarkably, a high J c value of 3.6 MA/cm 2 was achieved on the CeO 2buffered technical substrate at 77 K self-field, which is quite comparable with that grown on the LaAlO 3 single crystal. 29 It is known that accommodation field (B*), defined as J c (B*) = 0.9*J c (0), is normally associated with a single-pinning regime in the low field, while the parameter α in J c ∝ B −α corresponds to a collective interaction regime of vortices in the medium fields range. In this film, it is calculated that B* is 16 mT and α is about 0.67, which indicates that the flux pinning mechanisms are dominated by random and isotropic pinning on the film.…”

Rapid phase formation and interfacial reaction of YBa2Cu3O7−δ coated conducts by using high-rate crystallization of fluorine-free chemical solution

“…Furthermore, the growth of YBCO does not occur in the atmosphere of a very low pO 2 atmosphere, 12,21) as the transient liquid phase is absent. The BaMnO 3 phase was 25) In addition to the heterogeneous phase discovered on the substrate surface, Fig. 5(c) shows large-sized Y 2 O 3 particles (yellow circles) on the surface of the film, which is a region rich in Y elements as evidenced by the EDS Line Scan.…”

Interface reaction‐governed heteroepitaxial growth of YBa2Cu3O7‐δ film on CeO2‐buffered technical substrate

“…In our previous study, we proposed a simple and novel FF‐precursor solution based on all propionate salts and successfully prepared an YBCO film with superior crystal structure and high superconducting performance on a LaAlO 3 single crystal . However, when using CeO 2 capped substrate, a large amount of undesirable secondary phase appears which results in the structural deterioration and no superconductivity . Therefore, we suspect that the sequence of the BaCeO 3 and YBCO formation is very crucial.…”

“…21 However, when using CeO 2 capped substrate, a large amount of undesirable secondary phase appears which results in the structural deterioration and no superconductivity. 22 Therefore, we suspect that the sequence of the BaCeO 3 and YBCO formation is very crucial. In order to further study the role of interface effects on the YBCO growth and verify the feasibility of the FF-MOD process for industrial production, a technical substrate with well-developed multi-layer buffer architecture is used in this work.…”