Interface reaction‐governed heteroepitaxial growth of YBa₂Cu₃O_7‐δ film on CeO₂‐buffered technical substrate

Abstract

Due to the high growth rate and environmental‐friendly, fluorine‐free metal‐organic decomposition routes (FF‐MOD) have attracted more attention for growth of high‐quality YBa2Cu3O7‐δ (YBCO) films. Few works have been performed when using technical substrates. In this study, correlation among the sintering process, microstructure, and superconductivity of the YBCO was systematically established on the technical substrates capped with CeO2 layer. We found that the optimal process conditions are mainly related to the enhanced transient liquid phase and BaCeO3. Combined X‐ray diffraction and scanning electron microscopy analyses indicate that high‐quality growth of YBCO film is a trade‐off of two different competition phenomena during sintering: (a) the presence of enhanced transient liquid phase, (b) the formation of BaCeO3 at the interface. The former is beneficial to YBCO epitaxial growth/structure rearrangement, while the latter should be suppressed in view of minimizing YBCO partial decomposition triggered by the interfacial reaction. Moreover, we confirmed that both two aforementioned phenomena are somehow associated with the cross‐linkage between the sintering temperature and pO2 during the YBCO conversion. According to this systemic study, the key parameters are defined to avoid the BaCeO3 formation prior to the YBCO orientation nucleation. Structure and superconductivity of the YBCO film were also investigated. Remarkably, a high Jc value of 3.69 mA/cm2 (77 K, sf) was obtained in the YBCO film grown on the CeO2 technical substrate deposited under optimized deposition conditions, which is rather comparable with that on the LaAlO3 single crystal. TEM cross‐sectional observation reveals that the enhanced Jc (B) properties of the YBCO film are mainly contributed by high density of short stacking faults. This work demonstrates the feasibility of FF‐MOD to fabricate high‐performance YBCO films on the CeO2‐buffered technical substrate.

Preparation of GdBa2Cu3O6+x (GdBCO) precursor powder by spray‐drying a nitrate solution containing PEG

“…Our study has shown that spray‐dried precursor powders are a good alternative to the common mechanical mixture of precursor oxides for the synthesis of GdBCO powder. It also makes clear that eutectic melting enhances GdBCO growth; a result that is relevant in view of the present interest to develop suitable methods for preparing REBCO films from fluorine‐free precursors …”

“…It also makes clear that eutectic melting enhances GdBCO growth; a result that is relevant in view of the present interest to develop suitable methods for preparing REBCO films from fluorine-free precursors. 22,28…”

Two-dimensional X-ray diffraction characterization of growth mechanism of double perovskite-structured nanoparticles in thin films prepared via metal–organic decomposition

“…Chu et al has reported the optimal temperature for the nucleation of YBCO ranging from 815 to 820 °C. 25 In order to further investigate the nucleation of the YBCO nanocomposite films, the samples were subjected to different time intervals at a sintering temperature of 800 °C. Significant variations were found in the chemical composition of the 2D-XRD patterns for the YBCO/BYNO sample quenched for 5 min at 820 °C as compared to that of the YBCO/BYNO films at 800 °C as shown in Fig.…”