Pinning Centers in ISD-MgO Coated Conductors via EB-PVD

Abstract

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 .

Tailoring Microstructure and Superconducting Properties in Thick BaHfO3 and Ba2 Y(Nb/Ta)O6 Doped YBCO Films on Technical Templates

“…This is comparable to films deposited by electron-beam evaporation (cf. Stafford et al [2], 4.5 mol%, 8.6 mol% and 12.9 mol% BHO:YBCO, same color code). The J c (θ) curves of medium (green) and high BHO:YBCO (blue) are symmetrical to the ab-peak.…”

“…High-temperature superconductor (HTS) layers can be grown epitaxially onto different substrates by a number of physical and chemical deposition techniques, e.g. metal-organic chemical vapor deposition [1], electron-beam evaporation [2], pulsed laser deposition (PLD) [3]- [6] or chemical solution deposition [7]- [10]. Since grain boundaries (GBs) and texture are transferred by epitaxial growth into the HTS matrix, highlyoriented substrates/buffer layers are essential for high-J c performance of the functional layer in the low-field region, where GBs act as current blockers [11]- [15].…”

“….) compounds [2], [6]- [8], [25]- [30] or double-perovskite oxides as Ba 2 YNbO 6 [31], [32] or mixed Ba 2 Y(Nb 0.5 Ta 0.5 )O 6 (BYNTO) [33]- [36] to enhance vortex pinning and increase J c in high magnetic fields. A so-called nano-engineering, i.e.…”

Influence of Substrate Tilt Angle on the Incorporation of BaHfO3 in Thick YBa2Cu 3O7‐δ Films

“…So far, no c-axis correlated defects are achieved, i.e. no B||c peak appears in angle-dependent J c measurements of such samples [6]. TEM investigations show the formation of alternating YBCO layers and BHO/Y 2 O 3 platelets which are aligned parallel the YBCO ab-plane [5], [6].…”

“…no B||c peak appears in angle-dependent J c measurements of such samples [6]. TEM investigations show the formation of alternating YBCO layers and BHO/Y 2 O 3 platelets which are aligned parallel the YBCO ab-plane [5], [6]. In this work, we studied the influence of the vicinal angle α of miscut SrTiO 3 (mSTO) single crystal substrates on the growth mode of nanosized BHO structures in thick YBCO films.…”