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

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
.