High $J_{\rm c}$ ${\hbox {GdBa}}_{2}{\hbox {Cu}}_{3}{\hbox {O}}_{7-\delta}$ Coated Conductors on ${\hbox {CeO}}_{2}$-Buffered IBAD MgO Template Fabricated by Pulsed Laser Deposition

High quality GdBa
₂
Cu
₃
O
_7-δ
(GdBCO) coated conductors (CCs) were successfully fabricated on CeO
₂
-buffered IBAD MgO template by pulsed laser deposition (PLD). With the same energy density of 2 J/cm
²
, laser frequency of 8 Hz, and oxygen pressure of 300 mTorr, both target-to-substrate distance (
D
_ts
) and substrate temperature (
T
_s
) were systematically varied from 5.5 to 4.0 cm at
T
_s
of 780 °C and from 760 to 820 °C at
D
_ts
of 4.5 cm, respectively, to investigate their effects on the grain alignment, microstructure, and superconducting properties of GdBCO films. Biaxially aligned GdBCO films without
a
-axis oriented GdBCO grains could be deposited at
T
_s
higher than 780 °C and
D
_ts
shorter than 5.0 cm. At
T
_s
of 760 °C, a small amount of
a
-axis oriented and 45
^°
misaligned GdBCO grains was formed. The in-plane textures of GdBCO films were gradually improved when
D
_ts
decreased, while those were first improved with increasing
T
_s
up to 800
^°
C and then degraded at 820 °C. The highest critical current density (
J
_c
) of 3.9 MA/cm
²
and critical current (
I
_c
) of 195 A/cm-width (77 K, self-field) were achieved from the 500 nm GdBCO film deposited at 800°C with
D
_ts
of 4.5 cm . The
J
_c
values of GdBCO films were found to be sensitive to the in-plane texture and also to the presence of
a
-axis oriented grains and 45° misaligned grains.