GdBa 2 Cu 3 O 7−x (GdBCO) films doped with up to 13.6 mol.% BaHfO 3 (BHO) have been grown by electron beam physical vapor deposition (EB-PVD). A critical current density J c at 30 K, 3 T of 2.34 MA/cm 2 has been achieved for a doping level of 10.6 mol.%. This is the first report of artificial pinning centers being successfully incorporated into REBa 2 Cu 3 O 7−x (REBCO, RE = Y, Gd, Dy . . .) via EB-PVD. The samples were grown on Hastelloy tapes coated with a MgO buffer layer deposited by inclined substrate deposition. The J c of the samples was characterized at 77 K, 1 T and at 30 K, 3 T. An increase in J c (30 K, 3 T) upon Hf addition has been observed in the whole angular range α. The level of Hf addition was found to heavily influence the kind of nanoprecipitate formed, with low levels of Hf causing a reduction in the anisotropy of J c (77 K, 1 T) and higher levels of Hf resulting in the formation of nanoprecipitates elongated parallel to the GdBCO ab-plane, causing an increase in the anisotropy of J c (77 K, 1 T). The largest J c (77 K, sf) measured was 0.63 MA/cm −2 .

The technology of electron beam (e-beam) quantitative evaporation of oxide powders at THEVA is quite unique among the many standard in-situ growth methods of high-temperature superconducting (HTS) films. As well known for YBa2Cu3O7-x (YBCO) film growth the temperature and oxygen pressure should be in proximity of the YBCO stability line in the Bormann diagram. In case of e-beam quantitative evaporation, we observe a shift in the DyBa2Cu3O7-x (DyBCO) stability line towards lower pressures and higher temperatures compared to YBCO. We investigated the temperature and oxygen partial pressure boundaries of epitaxial DyBCO growth on inclined substrate deposited MgO (ISD-MgO) buffered Hastelloy tapes. For completeness, the influence of powder stoichiometry and evaporation rate on HTS epitaxial growth is shown. For the first time high-quality HTS films have been grown by e-beam quantitative evaporation without employing an oxygen shuttle and with oxygen in the chamber background instead.

Most commercial high-temperature superconducting coated conductors based on ion beam assisted MgO deposited templates use LaMnO3 (LMO) films as the terminating buffer layer. In contrast, coated conductors based on inclined substrate deposition (ISD)-MgO technology are still produced with homoepitaxial (homoepi)-MgO as the cap layer. In this work we report on the deposition of LMO buffer layers on ISD-MgO/homoepi-MgO by electron beam physical vapor deposition. The growth parameters of textured LMO films were studied systematically and their properties were optimized regarding the critical current density (J c) of the subsequently deposited DyBa2Cu3O7−δ (DyBCO) superconducting films. LMO films without outgrowths at the surface were obtained at growth rates of up to 4 Å s−1. Despite the formation of non-stoichiometric LMO films containing 59% La, single-phase films were obtained at substrate temperatures below 775 °C and at oxygen partial pressures of up to 4 × 10−4 mbar due to a large homogeneity region towards La. The J c values of DyBCO films deposited on LMO were found to be independent of the LMO thickness in a range from 50 nm to 450 nm. DyBCO films on LMO reach J c = 0.83 MA cm−2 at 77 K in zero applied field. This value is up to 30% higher than those of DyBCO films grown directly on homoepi-MgO. The wide range of LMO growth parameters and higher J c values of DyBCO on LMO compared to DyBCO on homoepi-MgO make this material attractive for its use in manufacturing coated conductors based on ISD-MgO technology.