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La2Zr2O7 (LZO) films were grown on different buffer architectures by radio frequency magnetron sputtering for the large-scale application of YBa2Cu3O7−x (YBCO)-coated conductors. The three different buffer architectures were cerium oxide (CeO2), yttria-stabilized zirconia (YSZ)/CeO2, and CeO2/YSZ/CeO2. The microstructure and surface morphology of the LZO film were studied by X-ray diffraction, optical microscopy, field emission scanning electron microscopy, and atomic force microscopy. The LZO films prepared on the CeO2, YSZ/CeO2, and CeO2/YSZ/CeO2 buffer architectures were preferentially c-axis-oriented and highly textured. The in-plane texture of LZO film on CeO2 single-buffer architecture was ∆ φ = 5.5° and the out-of-plane texture was ∆ ω = 3.4°. All the LZO films had very smooth surfaces, but LZO films grown on YSZ/CeO2 and CeO2/YSZ/CeO2 buffer architectures had cracks. The highly textured LZO film grown on CeO2-seed buffered NiW tape was suitable for the epitaxial growth of YBCO film with high currents.

GdBa2Cu3O7 − δ (GdBCO) films with different thicknesses from 200 to 2,100 nm are deposited on CeO2/yttria-stabilized zirconia (YSZ)/CeO2-buffered Ni-W substrates by radio-frequency magnetron sputtering. Both the X-ray diffraction and scanning electron microscopy analyses reveal that the a-axis grains appear at the upper layers of the films when the thickness reaches to 1,030 nm. The X-ray photoelectron spectroscopy measurement implies that the oxygen content is insufficient in upper layers beyond 1,030 nm for a thicker film. The Williamson-Hall method is used to observe the variation of film stress with increasing thickness of our films. It is found that the highest residual stresses exist in the thinnest film, while the lowest residual stresses exist in the 1,030-nm-thick film. With further increasing film thickness, the film residual stresses increase again. However, the critical current (I c) of the GdBCO film first shows a nearly linear increase and then shows a more slowly enhancing to a final stagnation as film thickness increases from 200 to 1,030 nm and then to 2,100 nm. It is concluded that the roughness and stress are not the main reasons which cause the slow or no increase in I c. Also, the thickness dependency of GdBa2Cu3O7 − δ films on the I c is attributed to three main factors: a-axis grains, gaps between a-axis grains, and oxygen deficiency for the upper layers of a thick film.