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

Abstract

High quality GdBa2Cu3O7-δ (GdBCO) coated conductors (CCs) were successfully fabricated on CeO2-buffered IBAD MgO template by pulsed laser deposition (PLD). With the same energy density of 2 J/cm2, laser frequency of 8 Hz, and oxygen pressure of 300 mTorr, both target-to-substrate distance (Dts) and substrate temperature (Ts) were systematically varied from 5.5 to 4.0 cm at Ts of 780 °C and from 760 to 820 °C at Dts 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 Ts higher than 780 °C and Dts shorter than 5.0 cm. At Ts 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 Dts decreased, while those were first improved with increasing Ts up to 800 °C and then degraded at 820 °C. The highest critical current density (Jc) of 3.9 MA/cm2 and critical current (Ic) of 195 A/cm-width (77 K, self-field) were achieved from the 500 nm GdBCO film deposited at 800°C with Dts of 4.5 cm . The Jc 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.