Growth of rare-earth zirconates-based pyrochlore buffer layers on YSZ for YBCO-coated conductors via chemical solution deposition

Abstract

Epitaxial films of rare-earth zirconates, RE2Zr2O7 (RE = La, Nd, Sm and Gd) were grown on yttrium stabilized zirconia (100) single crystal substrates using metal-organic deposition. A precursor solution of 0.25 '0.40 M concentration of total cations was spin-coated on yttrium stabilized zirconia substrates and crystallized at 1 000 8C for 3 h in Ar-4%H2 after calcination at 500 8C for 1 h. X-ray diffraction studies showed that the resulting pyrochlore RE2Zr2O7 films were highly textured with cube-on-cube epitaxy. Atomic force microscopy investigations revealed that the surfaces of La2Zr2O7, Nd2Zr2O7 and Sm2Zr2O7 films had a fairly dense and smooth microstructure without cracks and porosity, but that voids could be seen on the surface of the Gd2Zr2O7 film. Optical microscopy measurements confirmed that the Gd2Zr2O7 precursor solution showed poor wetting behavior on the substrate. It was concluded that the Nd2Zr2O7 and Sm2Zr2O7 films could be potentially used as buffer layers for YBa2Cu3O7-d coated conductors.

Microstructural evolution and its influence on oxygen diffusion in yttrium-doped ceria thin films

“…Actually, the rare earth C-type structural oxide with ordered oxygen vacancies, like Y 2 O 3 or Nd 2 O 3 , is a little similar to rare earth zirconate with pyrochlore structure, which can also be considered as an effective buffer layer material of coated conductors to reduce oxygen diffusion [10][11][12]. For example, La 2 Zr 2 O 7 with pyrochlore structure has been one of the common superconducting buffer layer materials due to its ordered alignment of oxygen vacancies [12,13]. However, there are few reports regarding to the influence of structure evolution of ceria doped with rare earth ions on oxygen diffusion when it is applied in a buffer layer.…”