Effects of the Grain-Boundary Angle of the Buffer Layer on the In-Field Critical Current Density in (Y 0.77Gd0.23)Ba2Cu3Oy + BaZrO3 Nanoparticle Coated Conductors

We fabricated Y
_0.77
Gd
_0.23
Ba
₂
Cu
₃
O
_y
[(Y,Gd)BCO] and BaZrO
₃
(BZO) nanoparticle doped (Y,Gd)BCO ((Y,Gd)BCO+BZO) films on CeO
₂
buffered metallic substrates [ = coated conductor (CC)] by using trifluoroacetate metal organic deposition (TFA-MOD). In this paper, in order to investigate the influence of grain-boundary angles of CeO
₂
buffer layer (Δφ
_CeO2
) on crystallinity and superconducting properties of (Y,Gd)BCO, the TFA-MOD films are fabricated on metallic substrates with various Δφ
_CeO2
. The Δφ of the superconducting layer decreases with decreasing Δφ
_CeO2
in both CCs. The self-field critical current density (J
_c
^s.f.
) of (Y,Gd)BCO+BZO CC with Δφ
_CeO2
= 2.0° is 5.8 MA/cm<;sup>2<;/sup> at 77 K, which is 1.5 times higher than that of CCs with Δφ
_CeO2
= 4.0°. Moreover, the (Y,Gd)BCO+BZO CC with Δφ
_CeO2
= 2.0° showed the minimum critical current density (J
_c,min
) of 0.81 MA/cm
²
at 77 K and 3 T. Thus, the improvement of the grain boundaries by using the improved buffer layer has an important role in the improvement of J
_c
in TFA-MOD REBa
₂
Cu
₃
O
_y
CCs.