We report on the in situ preparation of Y Ba2Cu3O7−δ films uniformly deposited over large areas,>20 × 20 cm2, at 690 °C by thermal co-evaporation onto Ni–5 at.% W biaxially textured tapes buffered with e-beam evaporated CeO2. Typically, the thickness of the YBCO and CeO2 layers was 0.9 and 0.1 µm, respectively. Deposition rates were 0.2 and 2.5 nm s−1, respectively. X-ray diffraction θ–2θ Bragg–Brentano and pole figure measurements, and Nomarsky optical and SEM microscopy analysis show good biaxial texture of both layers, sharp interfaces and the absence of cracks. Midpoint critical temperatures, Tc, fall reproducibly in the 87–88 K range with transition widths ΔTc = 1 K. Remarkably high transport critical current densities, Jc, in the 2.0–2.5 MA cm−2 range are achieved at 77 K in 1 cm long samples. The above deposition route appears to be promising for the development of long-length YBCO coated conductors thanks to the relatively low deposition temperature, the high degree of uniformity over large areas and the simple single buffer layer architecture.

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We report on the in-situ preparation and characterization of coated conductors consisting of a ≈ 400 nm thick YBCO superconducting film grown by thermal co-evaporation on a ≈ 200 nm thick CeO2 buffer layer grown by e-beam evaporation on biaxially textured Ni-Cr and Ni-V substrates. We studied the degree of texture of both YBCO and CeO2 layers as a function of substrate temperature during deposition and of oxygen partial pressure. X-ray diffraction patterns reveal that the highest degree of (100) texture of the buffer layer, necessary for the subsequent growth of the YBCO film with the desired c-axis orientation, is achieved at substrate temperatures of the order of 670-730°C. The backfilling of the chamber with oxygen during the cooling-down of the substrates after deposition of the CeO2 layer greatly improves the degree of crystallization of the buffer layer. YBCO films show good superconducting properties with critical temperatures Tc of the order of 87 K. Work is in progress to scale up the process for long tapes.

We have applied pulsed laser deposition (PLD) to fabricate YBCO/YSZ films (short length) onto biaxially textured NiFe substrates. Macroscopic characterization of the samples has been carried out by electrical measurements, XRD patterns and pole figures. Our best films are characterized by T cs around 89 K and transition widths around 5–6 K. Bragg–Brentano spectra and pole figures acquired on the {111} peak for YSZ and {013} for YBCO show the achievement of the correct crystalline structure and stoichiometry both in YSZ and in YBCO layers. They are largely in-plane textured (respectively (001) <110> for YSZ and (001) <100> for YBCO), and the superconducting YBCO layer exhibits a relatively low mosaicity. Atomic-force microscopy (AFM) analysis confirmed the presence of large grains (1–2 μm typical dimensions), and the occurrence of a complex morphology in the YBCO layer.