Feasibility study of the synthesis of YBiO3 thin films by aqueous chemical solution deposition as an alternative for CeO2buffer layers in coated conductors

Abstract

In this paper, the formation of YBiO₃ starting from a new water-based precursor was studied in both bulk and thin films under different processing conditions. The decomposition of this precursor was studied with thermogravimetric and differential thermal analysis and the reaction products were identified with X-ray diffraction. Our results show that starting from our water-based solutions, polycrystalline YBO powders can be obtained in air and argon atmospheres. Once the partial oxygen pressure was reduced using an Ar–5% H₂ mixture, reduction of Bi³⁺ was observed, restricting YBO formation. When thin film synthesis on single crystal LaAlO₃ is performed, clear differences in processing conditions were observed regarding powder synthesis. The addition of water vapour to the argon gas is necessary in order to suppress Bi₂O₃ sublimation. Using the appropriate synthesis conditions, well-textured, homogeneous, dense and smooth (R_a = 2.6–1.8 nm) films of 140 nm and 40 nm thickness are obtained at sinter-temperatures as low as 750 °C. YBa₂Cu₃O_7−x deposited by Pulsed Laser Deposition on the 40 nm thick YBiO₃ films yielded a J_c (77 K) of 3.6 MA cm⁻² in self-field, indicating the potential of this material as an alternative for CeO₂ in the CeO₂/La₂Zr₂O₇/Ni–5%W and CeO₂/YSZ/Stainless Steel coated conductor architectures.