This paper describes the microstructure to improve the magnetic field dependence of the critical current density, Jc, of Y(RE)Ba2Cu3O7−x [Y(RE)123, RE: Gd and Sm] coated conductors. A columnar microstructure 10nm in diameter has been obtained by using Y123 targets including yttrium-stabilized zirconium for the pulsed-laser deposition. This columnar structure, composed of BaZrO3 and Y123, continued from the substrate to the surface of the film 0.25μm in thickness. We have named it “the bamboo structure” from its morphology. The bamboo structure was effective for increasing Jc in a magnetic field especially parallel to the c-axis. We have also found stacking faults in RE123 effective to improve Jc.
We prepared GdBa2Cu3O7−δ
(Gd-123) coated conductors by the pulsed laser deposition (PLD) method on
PLD-CeO2/ion-beam assisted
deposition (IBAD)-Gd2Zr2O7
(GZO)/hastelloy metal substrate tapes. The Gd-123 film showed a higher critical current density
(Jc) in magnetic
fields (B) and higher
critical temperature (Tc) than those of YBa2Cu3O7−δ
(Y-123) film. The Gd-123 film exhibited a high
Jc value
of 0.19 MA cm−2
at 3 T () in liquid nitrogen (77 K), and the
Tc value was
93.8 K. The Jc
value at 3 T was twice as high as that of Y-123 film. Moreover, the angular dependence in magnetic fields
of Jc
for Gd-123 was also superior to that of Y-123. The reduction of
Jc
by the magnetic field angle for Gd-123 was less sensitive than
that in Y-123. Furthermore, Gd-123 clearly exhibited a peak at
0°
() as well as at 90°
() in the relationship of Jc on the
magnetic field angle curve (Jc–θ), while Y-123
had no peak at 0°. These superior characteristics are considered to be due to the existing
defects, such as stacking faults, as observed by transmission electron
microscopy. PLD-Gd-123 coated conductors, with pinning-effective defects, high
Jc and low
anisotropy in Jc–θ, show promise for future applications.
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